’62 brit-plex 45w - stewmac.com...stewmac.com 1 ©2019 stewmac ’62 brit-plex 45w amplifier kit...
TRANSCRIPT
A S S E M B LY I N S T R U C T I O N SWith loads of helpful tips!
’62 BRIT-PLEX 45W A M P L I F I E R K I T
ORIGINAL BRITISH CIRCUIT
The amp thatstarted a revolution
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Contents
About this iconic amp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Parts list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Tools and supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Amp voltages are seriously dangerous! . . . . . . . . . . . . . . . . . . . . . . . . . . 6
How to use a snuffer stick . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
How to read resistor values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Capacitor values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Complete wiring diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Prepping the turret board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Tips for great soldering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Installing the chassis-mounted components . . . . . . . . . . . . . . . . . . . 11
Wrapping parts onto the turret board . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Installing the turret board in the chassis . . . . . . . . . . . . . . . . . . . . . . . 37
Installing parts and preparing for testing . . . . . . . . . . . . . . . . . . . . . . 42
Testing and troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Final assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Tips for using this amp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Photograph of completely wired chassis . . . . . . . . . . . . . . . . . . . . . . . 47
Learning more: secrets revealed in the schematic . . . . . . . . . . . . . . 48
Circuit schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
More iconic amp kits from StewMac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Full page wiring diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Tube replacement chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
COPYRIGHT WARNINGThis material is protected by copyright and has been created by and solely for the purposes of StewMac . You may not sell, alter or further reproduce any part of this material, or distribute it to any other per-son . Where provided to you in electronic format, you may only print from it for your own private use . Failure to comply with the terms of this warning exposes you to legal action for copyright infringement .
How to build this kit!
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’62 BRIT-PLEX 45W AMPLIFIER KIT ORIGINAL BRITISH CIRCUIT
This amp is an ICONThis is the JTM45 circuit, the very first circuit produced by Marshall and modeled after a 5F6A Fender Bassman . To keep the weight manageable, this amp was designed as a head to pair with a separate 4x12 speaker cabinet .
By the mid-60s the JTM45 had taken the crown from the AC30 as the must-have British amp . While it might not have as much grit and guts as the subsequent Marshall amps, this is the seminal circuit of a musical empire .
StewMac ICON KITS bring classics that are no longer made, or are simply unaffordable, within reach . And the best part is you get to build them with your own hands .
We give painstaking attention to parts selection, authentic materials, and instantly recognizable details—everything that makes the originals so sought after .
Build it with StewMacThese immersive instructions walk you through every step of creating your ’62 Brit-Plex . And you’ll learn a lot, gaining a deep knowledge of your amp’s inner workings .
Follow our steps closely for safety, too: we’ve carefully laid out a path that even newcomers can follow in handling electrical components .
Building an amp can seem daunting, but nobody makes it easier than StewMac . Watch for helpful tips along the way, too—we’re here to help!
Let’s get building!
Iconic British tone is now in your hands
Be excited!Your new StewMac ’62 Brit-Plex will be a blast to play through and even more fun to build .
This amp is favored by blues and rock guitarists for its rich, articulate clean tones and exceptional sustain: creamy, warm and a little crispy . Rich in harmonic feedback, this was the amp that started a rock and roll revolution .
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Here’s how to build this amp!
Wiring goes like this:1. First, you’ll wrap the leads, connecting them without solder. 2. Then double-check all the connections. Don’t rush!3. When everything checks out, it's time to solder. The numbered steps tell you when.
Get the turret board ready, starting at Step 1 on page 9.You’ll prep the metal chassis too.
Learn more:You don’t need to read the schematic, but it’s fun! See how your guitar’s signal gets processed into sound on page 49.
Sort your components by type, using the parts list.Quick look:
OutputGain Processing Gain GainProcessing Negative feedback
See page 9
#00000 © 2019 StewMac
GroundJackTransformer Preamp tube
plategrid
cathode
Power tube
grid
plate
cathode
screen
Capacitor Electrolytic Cap. DiodeResistor Potentiometers Rectifier tube
plate cathode
filamentplate
Shieldedcable
’62 BRIT-PLEX45WO R I G I N A L B R I T I S H C I R C U I T
Output
Gain
Gain Gain
Power
Processing Processing
Pow
er
Negative Feedback
BASS
TREBLE
PRESENCE
VOLNORM VOL
BRIGHT
MID
6V5V
MainsSTANDBY
FUSESlow-blow1 Amp
FUSESlow-blow500 mA
LIGHT120V
TRANSFORMERMojo 18W power
V65AR4
32μF
.022μF
.1μF
.1μF
250μ
F
.022
μF
.022
μF
.022μF
.022μF68K
68K
68K
68K
250pf
10K 2W 10K 2W
1K 5
W
470Ω
2W
470Ω
2W
500p
f
32μF
32μF
32μF
8μF
8μF
220K
15K1N4007 10KL
68K
.1μF
.1μF
1M
1MA
1M
220K
220K
25KL
5KL
10K
5.1K
5.1K
100K
100K
56K
100K
820Ω
820Ω
100K
250K
A
1MA
82K
470Ω
.047
μF
SPEA
KER
S
CH
2 IN
PU
TSC
H 1
INP
UTS
16
8
4
Mojo 777
V312AX7
V112AX7
V212AX7
V4EL34
V5EL34
1M1M
27K
1MA
270K
270K
47pf
2
1
3
6
7
8
1
2
3
6
7
81
2
3
6
7
8
8
8
5
5
4
4
3
3
1
1
250p
f
A
A
TRANSFORMERMojo 18W ouput
100K
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Hardware
r (4) 10-32 machine screw, 1-1/2"r (4) 10-32 locknut
r (6) 8-32 machine screw, 1/4"r (10) 8-32 locknut
r (4) 6-32 machine screw, 1/2"r (4) 6-32 locknut
r (4) 4-40 threaded standoff, 1/2"
r (14) 4-40 machine screw, 1/4"r (6) 4-40 locknut
r (2) Switch mounting nut
r (2) Filter cap mounting clamp
r (3) Rubber grommet
Capacitors & diode
r (1) 47pF 500V silver mica
r (2) 250pF 500V silver mica
r (1) 500pF 500V silver mica
r (4) .1μF 600V Mojo Dijon
r (5) .022μF 600V Mojo Dijon
r (1) .047μF 600V Mojo Dijon
r (2) 8μF 150V Sprague Atom
r (1) 250μF 25V aluminum electrolytic
r (2) 32μF+32μF 500V electrolytic filter cap
r (1) 1N4007 1000V rectifier diode
r (1) Cabinet
r (1) Chassis
r (1) Turret board
r (1) Faceplate/backplate set
Resistors
r (1) 470Ω .5W carbon composite
r (2) 820Ω .5W carbon composite
r (2) 5.1K .5W carbon composite
r (1) 10K .5W carbon composite
r (1) 15K .5W carbon composite
r (1) 27K .5W carbon composite
r (1) 47K .5W carbon composite
r (1) 56K .5W carbon composite
r (5) 68K .5W carbon composite
r (2) 82K .5W carbon composite
r (5) 100K .5W carbon composite
r (3) 220K .5W carbon composite
r (2) 270K .5W carbon composite
r (4) 1M .5W carbon composite
r (2) 470Ω 2W metal oxide
r (2) 10K 2W metal oxide
r (1) 1K 5W ceramic
(also called a can capacitor)
250+
8µF
510K47
32μF +
32μF
500V
.047μF
.022μF
.1μF
250μF
5W 1K
Brown Green Orange Gold
Yellow Violet Orange Gold
Red Violet Yellow Gold
Yellow Violet Brown Gold
Brown Black Orange Gold
Yellow Violet Brown Gold
Gray Red Brown Gold
Green Brown Red Gold
Brown Black Orange Gold
Red Violet Orange Gold
Green Blue Orange Gold
Blue Gray Orange Gold
Gray Red Orange Gold
Brown Black Yellow Gold
Red Red Yellow Gold
Brown Black Green Gold
A magnifier helps!
Parts list
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Parts listTubes, lamps, fuses, and sockets
r (1) Two-lug jack
r (5) Four-lug jack
r (3) Nine-pin tube socket
r (3) Shield for nine-pin tube socket
r (3) Eight-pin tube socket
r (3) Tension clip for eight-pin socket
r (3) 12AX7 preamp tube (also called ECC83S)
r (2) EL34 power tube
r (1) 5AR4 rectifier tube (also called GZ34)
r (2) Fuse socket
r (1) Fuse (3 amp, slow blow)
r (1) Fuse (500 milliAmp, fast blow)
r (1) Indicator light
r (1) Power inlet
Control pots and more
r (1) 10KL bias pot
r (3) 1M control pot (A-audio taper)
r (1) 5K control pot (L-linear taper)
r (1) 25K control pot (L-linear taper)
r (1) 250K control pot (L-linear taper)
r (1) Impedance selector switch
r (7) Knob
r (3) Three-lug terminal strip
r (1) Power switch (2 lugs)
r (1) Standby switch (2 lugs)
Wire
r (1) Black wire
r (1) White wire
r (1) Green wire
r (1) Yellow wire
Heat-shrink tubing
r (3) 1/8” diameter (2-1/2” length)
r (1) 1/16” diameter (2-1/2” length)
Transformers
r (1) Power transformer
r (1) Output transformer
r (1) Filter choke12A
X7EL34
5AR4
4
3 2
18
76
5
6
4 3 21
987
5
Vintage-style push-back wire lets you push the insulation back instead of trimming it. BUT: Trimming it still works better!
1MA
5KL
25KL
25
0KL
10KL
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#0531 StewMac Solder Monster
#3000 Guitar Tech Screwdriver Set
#1606 Wire Stripper
#1607 Wire Cutter
#0501 Solomon SL-30 Soldering Station
#1609 Round Nose Bending Pliers #0505
Kester Pocket-Pak Solder
StewMac’s Solder Monster holds parts while you solder
Tools and supplies
Required Phillips screwdrivers, #1 and #2 Item #3000 Guitar Tech Screwdriver Set
Needle nose pliers Item #1610 Long Nose Pliers
Wire cutter Item #1607 Wire Cutter
Wire stripper Item #1606 Wire Stripper
Soldering iron (preferably 40W) Item #0501 Solomon SL-30 Soldering Station
Solder (at least one Pocket-Pak) Item #0505 Kester Pocket-Pak Solder
Solder sucker Item #0503 Solomon Solder Sucker
Drill with a 5/32" bit For mounting turret board and filter cap
Ruler Item #4905 StewMac Shop Rule
Digital multimeter Item #3618 Fieldpiece Pocket Multimeter
Snuffer stick (bleed resistor) Item #1552 Snuffer Stick
Pencil Wooden chopsticks Glue Wood glue, white glue, or contact cement for gluing a paper label inside the cabinet
Butane lighter or matches For heating heat-shrink tubing
Contact cement
Helpful Round nose bending pliers Item #1609 Round Nose Bending Pliers
Solder wick Item #0504 Solder Wick, 5-foot roll
Soldering aids Item #0521 StewMac Soldering Aids
Soldering stand Item #0506 Solomon Soldering Stand
Solder Monster, or helping hand tool Item #0531 StewMac Solder Monster
Chassis stand Item #10750 Chassis Stand
Printed circuit board vise Scratch awl or center punch Item #3000 Guitar Tech Screwdriver Set
Tray for loose parts Bias meter for accurate biasing Item #1580 VHT Tube Tester + Amp Bias Meter
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High voltage, even when unpluggedWhen you turn on an amp, the capacitors are designed to take on a charge and hold it . That stored voltage is enough to injure you seriously, or even kill you .
These components aren’t a threat until the first time you plug the amp in . The stored electricity can be safely discharged to ground with a snuffer stick . See how to use it below .
Once your amp has been turned on, don’t touch the wiring with your bare hands—even after turning it off . If you need to press on a contact, use a chopstick or Sharpie marker, which are both non-conductive . Don’t use a pencil, because graphite is conductive .
It’s important that you understand the dangers so you’re working safely . Here’s how to do it right .
Wear rubber-soled shoesRubber soles increase the insulation between yourself and the ground .
Take off your ringA metal ring on your finger can bridge a hot connection to ground .
Wear safety glassesRosin-core solder sometimes bubbles up, and it can spew molten specks into the air . You don’t want molten solder in your eyes .
It’s better not to work aloneElectrical shocks can incapacitate you, and having someone available to call 911 can be a lifesaver .
How to use a snuffer stickTo discharge a capacitor, clip the snuffer stick lead to ground—preferably a mounting bolt on the power transformer . Hold the tip of the stick to the cap’s positive lead and use your multimeter to watch the voltage drain to less than 18V .
Take breaks and stop when you’re tiredFatigue leads to mistakes, and no one can afford mistakes when working with electricity .
Stay suspiciousWhether it’s the first time you’ve been inside a live ampli-fier or the 100th time, don’t become complacent . If you discharge the caps and walk away for a few minutes, check again for residual voltage when you return . Capacitors can self-charge through a phenomenon known as dielectric memory .
Check before powering on It’s easy to forget that you a left a stray tool or wire in the chassis . It’s also easy to forget to re-attach the speaker wire, and that can fry an output transformer in seconds . Constant vigilance is your friend when working on amps .
Always unplug itUnplug the amp whenever you don’t specifically need it plugged in . Some points are always hot when the amp’s plugged in, even if the power switch is off . These points include the lugs on the fuse socket, power switch, and standby switch .
Amp voltages are seriously dangerous!
Professionals who work on amps take these safety habits very seriously
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A resistor’s value—the amount of resistance it creates—is rated in ohms (Ω) . Larger ohm values mean more resistance . For example, a 100Ω resistor creates ten times as much re-sistance as a 10Ω resistor .
The resistors used in amplifiers are too small to have value numbers printed on them . Instead, a system of colored bands tells their values . The key to reading these bands is provided below . However, an easier way to decode these bands is to download one of the many smartphone apps for this purpose .
One band will be the nearest to an end of the resistor . That band tells the first value . Combine it with the value of band 2 to get a two-digit number (68 in our example below) . Multiply that number by band 3 (68 x 1,000 = 68,000) . Thou-sands are represented by the letter K, so this resistor is 68K (kilo-ohms, or KΩ) .
If there is a fourth band, it will be either silver or gold . This indicates the tolerance allowed during manufacturing . The resistors used in this kit have a +/- 5% tolerance, represented by a gold band 4 .
A magnifying glass helps a lot . The bands on a 470Ω resistor are yellow/violet/brown, and the bands on a 47K resistor are yellow/violet/orange . They’re easily confused!
Can’t read the colors?You can always use a multimeter to test a resistor’s value . Set your meter to ohms and connect the test leads on each side of the resistor .
Capacitor values are typically printed on the component . The key values with caps are their capacitance and voltage .
Think of a capacitor as a container that can hold electricity . Capacitance, measured in farads, refers to how much elec-tricity this container can hold—its capacity . One farad (1F) would be much too large for use in an amplifier . Caps for amps are rated in millionths of a farad, called microfarads (μF), or trillionths of a farad: picofarads (pF) . The voltage spec for a cap refers to how much DC voltage it can handle at any given time .
A unique property of capacitors is that they don’t allow DC current to flow past them, only AC current . This is important in parts of an amplifier circuit, such as the path between a preamp stage and a power amp stage . Here, a “coupling capacitor" will block DC voltage, allowing only the AC guitar signal to pass .
Filter capsCapacitors also filter out 60Hz hum, or “ripple," after the AC current from the wall is converted to DC . These capacitors are called filter caps, because they filter out the ripple from a power supply . The filter caps in this amp are the 32μf + 32μf electrolytic can capacitors . This means that each physical capacitor has two caps inside, each with their own positive lug, and they share a common negative lug .
Electrolytic capsElectrolytic capacitors contain electrolyte: a liquid or gel that gives them a large storage capacity . Electrolytic caps are typically polarized .
Polarized capsSome capacitors have polarity and some don’t . It’s extremely important to install polarized caps correctly in a circuit . The positive lead of an electrolytic cap will be indicated by an indented ring around one edge of the capacitor . The nega-tive lead will often be indicated by a band of arrows pointing to the negative lead .
Installing capacitors with the polarity backwards will make the circuit malfunction and quickly destroy the capacitor—even causing it to explode .
Band 1 Band 2 Band 3 Band 4 1st Digit 2nd Digit Multiplier Tolerance
6 8 x1,000 +/- 5%
68K +/- 5%K = 1,000
Blue
Read this band first (closest to an end)
Gray Orange Gold
BLACK 0 0 1 None +/- 20%
BROWN 1 1 10
RED 2 2 100
ORANGE 3 3 1,000
YELLOW 4 4 10,000
GREEN 5 5 100,000
BLUE 6 6 1,000,000
VIOLET 7 7
GRAY 8 8 0.01 +/- 10% SILVER
WHITE 9 9 0.1 +/- 5% GOLD
NegativePositive
+ 25μF
32μ
F +
32μ
F50
0V
How to read resistor values Capacitor values
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V5EL34
V4EL34
POWER STANDBY INDICATORLIGHT
PRESENCE BASS MIDDLE TREBLE HIGH TREBLELOUDNESS 1
NORMALLOUDNESS 2
INPUT 1(HIGH TREBLE)
INPUT 2(NORMAL)
POWER INLETFUSE H.T. FUSE IMPEDANCE
V65AR4
V312AX7
V212AX7
V112AX7
SPEAKER EXTENSIONSPEAKER
-
43
2 1
87
65
43
2 1
87
65
43
2 1
87
656
43 2 1
9875 6
43 2 1
9875 6
43 2 1
9875
250KL
25KL
1MA
5KL
1MA
1MA
D
C
-
B
A
-
1
2
1
2
3
41
23
4
12
43
12
43AA
BB
12
43
12
43AA
BB
.1μF
.047μF
2
1 23
52
515049484746454443424140393837
2824 26
30 3327
35
29 31 3225
34
36
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
+
8µF
+
8µF
.022μF
.022μF
.022μF
.1μF
.1μF
.1μF
47
5W 1K
250μF
.022μF
.022μF
500pF
250
250
Complete wiring diagram
Our diagrams show a flat view of the metal chassis
Here’s the complete Brit-Plex 45 wiringWhen you’ve finished the kit, you’ll have connected all the parts shown in this wiring diagram . If it looks complex now, don’t worry; we’ll start at the very beginning and do this one step at a time .
Your amp-building skills will get stronger with each step!
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Start by prepping the turret board
n Wrap the leads tightly for a good electrical contact before soldering . Don’t use solder to “glue" loose joints .
n Melt a small amount of solder onto the tip of the iron (“tinning" the iron) . Hold the tip against the joint for a few seconds, until the connection reaches soldering temperature .
Also tin component leads like multi-strand wires to help the solder flow .
You’re ready to build!
Tips for great soldering!
STEP 1
Number the turretsThe steps refer to the turrets by num-ber . Number the turrets on your board by putting tape along the edges and writing with a fine-point marker . You’ll remove the tape before installing the board .
Leave the turrets in the center of the board (#24–34) unmarked . You can identify these turrets by referring to the diagrams .
n Keep your soldering tip clean by wiping it often on a damp sponge . Keep it tinned by occasionally melting a little solder onto it .
n Feed solder to the connection not to the iron . Keep the iron on the con-nection for a second longer to allow time for all of the flux to cook out of the joint .
n Don’t ever blow on the hot solder or touch anything until the joint is completely cool . A good solder joint is shiny—a sign that it was left to cool undisturbed .
2
1 23
52
515049484746454443424140393837
2824 26
30 3327
35
29 31 3225
34
36
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
n Trim away the excess wires after the joint has cooled .
n Plan ahead so each joint is only soldered once . Resoldered joints are messy and more likely to fail .
n Position the parts so their specs face out so you can read them later . Many builders also align resistor bands to read in the same direction .
n How much insulation to strip? With plastic insulation, strip 3/8" from the wire ends . Push-back wire works best when you strip away about 1/4" of the cloth wrap .
Component leads are wrapped onto the turrets and left unsoldered while you add other parts . This way, you can check your work and make correc-tions without having to redo a solder joint . Ideally you solder a turret only once, which is the best way to get clean, trouble-free connections .
When it's time to solder, flow the solder all the way around the turret .
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OUTPUT TRANSFORMER(Mounted outside)
FILTER CHOKE(Mounted outside)
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late
wit
h th
e fo
ur-lu
g sp
eake
r ja
ck a
nd t
he m
ains
fus
e so
cket
. Re
mov
e on
e of
the
fiber
was
hers
from
the
four
-lug
spea
ker j
ack
and
inst
all t
his
jack
w
ith o
ne fi
ber
was
her
insi
de
the
chas
sis
and
the
nut
and
pla
stic
was
her
outs
ide
the
chas
sis .
Inst
all t
he m
ains
fuse
soc
ket
by r
emov
ing
the
nut,
slid
ing
the
sock
et
thro
ugh
the
chas
sis,
and
fast
enin
g it
with
th
e nu
t .
S
TE
P 3
Pre
p t
he
thre
e te
rmin
al s
trip
s W
ith
a w
ire
cutt
er, s
nip
th
e m
oun
tin
g ho
les
on th
e th
ree-
lug
term
inal
str
ips
as
pic
ture
d ab
ove .
Cu
t tw
o 1
" p
iece
s o
f g
reen
wir
e an
d re
mov
e th
e in
sula
tion .
Wra
p a
nd s
old
er
one
of th
e w
ires
acro
ss o
ne o
f the
str
ips,
el
ectr
ical
ly c
on
nec
tin
g t
he
thre
e lu
gs .
Th
is w
ill b
e us
ed a
s a
gro
und
ing
str
ip .
Rep
eat
this
pro
cess
wit
h t
he
seco
nd
term
inal
str
ip . Y
ou n
ow h
ave
two,
thre
e-lu
g gr
ound
ing
strip
s .
The
third
term
inal
str
ip w
ill b
e tu
rned
in
to a
tw
o-lu
g gr
ound
ing
strip
, wit
h on
e lu
g le
ft u
ngro
und
ed .
Cut a
3/4
" pie
ce o
f gre
en w
ire a
nd re
mov
e th
e in
sula
tion .
Wra
p a
nd s
old
er th
e w
ire
acro
ss t
wo
nei
gh
bo
rin
g l
ug
s o
n t
his
st
rip . L
eave
the
thi
rd lu
g un
conn
ecte
d .
This
un
con
ne
cte
d l
ug
wil
l b
e u
sed
to t
erm
inat
e an
un
use
d t
ran
sfo
rmer
w
indi
ng .
S
TE
P 4
Inst
all t
hre
e ru
bb
er g
rom
met
sSq
uee
ze t
hes
e in
to t
he
thre
e h
ole
s as
sh
own .
The
se p
rovi
de
stra
in re
lief f
or th
e tr
ansf
orm
er w
ires
that
will
pas
s th
roug
h th
e m
etal
cha
ssis
.
Insi
de
a tr
ansf
orm
er is
a p
rimar
y co
il an
d a
seco
ndar
y co
il . Y
our 1
20V
AC
hou
seho
ld
curr
ent g
oes
into
the
prim
ary
coil
and
is
tran
sfor
med
into
hig
her
volt
age
whi
ch
is o
utp
ut
by
the
seco
nd
ary
coil .
Th
is
volt
age
can
be
as h
igh
as 5
00V,
and
is
refe
rred
to a
s hig
h te
nsio
n (H
.T .) .
The
lead
s co
nnec
ting
to t
hese
tw
o co
ils a
re c
alle
d p
rimar
y an
d se
cond
ary
lead
s .
S
TE
P 5
Mo
un
t th
e p
ow
er t
ran
sfo
rmer
The
pow
er tr
ansf
orm
er h
as tw
elve
lead
s .
Sepa
rate
thes
e in
to c
olor
-cod
ed p
airs
and
tw
ist t
hese
pai
rs to
geth
er:
Tw
o re
d le
ads
Two
gree
n le
ads
Two
yello
w le
ads
Solid
bla
ck a
nd s
trip
ed b
lack
/blu
e
Strip
ed b
lack
/yel
low
and
str
iped
bla
ck/w
hite
Feed
all
the
tran
sfor
mer
lea
ds in
to t
he
chas
sis
thro
ugh
the
squa
re h
ole
with
the
gree
n le
ads
clos
est
to t
he t
ube
sock
ets
and
the
red
lead
s on
the
sam
e si
de
as th
e fr
ont p
anel
con
trol
s .
Inst
all
the
tran
sfo
rmer
on
th
e o
uts
ide
of t
he c
hass
is, u
sing
fou
r 8-
32 lo
cknu
ts
insi
de .
Ad
d t
he t
erm
inal
str
ips
at t
hree
co
rner
s as s
how
n . T
he tw
o-lu
g gr
ound
ing
stri
p g
oes
on t
he b
ack
corn
er n
ear
the
mai
ns
fuse
so
cket
an
d t
he
thre
e-lu
g g
rou
nd
ing
str
ips
sho
uld
be
pla
ced
as
show
n on
the
wiri
ng d
iagr
am .
S
TE
P 6
Mo
un
t th
e o
utp
ut
tran
sfo
rmer
One
sid
e of
the
out
put
tra
nsfo
rmer
has
b
lue,
red
, an
d b
row
n w
ires
. Th
ese
are
the
pri
mar
y le
ads
of
the
tran
sfo
rmer
. P
ass
thes
e th
ree
wir
es t
hro
ug
h t
he
gro
mm
eted
ho
le c
lose
st t
o t
he
fro
nt
pan
el o
f the
cha
ssis
.
The
othe
r sid
e of
the
outp
ut tr
ansf
orm
er
has
oran
ge,
gre
en, y
ello
w, b
row
n, a
nd
bla
ck w
ires
. Th
ese
are
the
seco
nd
ary
lead
s o
f th
e tr
ansf
orm
er .
Twis
t th
e o
ran
ge
+ g
reen
+ y
ello
w s
eco
nd
ary
wire
s to
get
her .
Pass
the
se t
hrou
gh t
he
gro
mm
eted
ho
le c
lose
st t
o t
he
bac
k p
anel
, alo
ng w
ith t
he b
row
n an
d b
lack
w
ires
(five
wire
s th
roug
h th
is g
rom
met
) .
Use
four
8-3
2 x
1/4"
mac
hine
scr
ews
with
lo
ck n
uts t
o m
ount
the
tran
sfor
mer
on
the
outs
ide
of th
e ch
assi
s .
S
TE
P 7
Mo
un
t th
e fi
lter
ch
oke
The
filte
r cho
ke is
a si
ngle
-coi
l tra
nsfo
rmer
, al
so k
now
n a
s an
in
du
cto
r, th
at h
elp
s sm
ooth
out
the
AC
rip
ple
left
ove
r in
the
high
vol
tage
sig
nal .
This
mea
ns th
e fil
ter
cho
ke o
nly
has
tw
o le
ads,
bot
h b
lack
. Tw
ist
thes
e le
ads
tog
eth
er a
nd
thr
ead
them
thr
oug
h t
he
gro
mm
eted
hol
e in
th
e m
iddl
e of
the
chas
sis .
Use
tw
o 8
-32
mac
hin
e s
crew
s an
d lo
cknu
ts to
mou
nt th
e fil
ter c
hoke
out
side
of
the
chas
sis .
3. S
olde
r
1. S
nip
2. W
rap
stew
mac
.co
m
12
©20
19 S
tew
Mac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
IND
ICAT
OR
LIG
HT
PRES
ENCE
BASS
MID
DLE
TREB
LEH
IGH
TRE
BLE
LOU
DN
ESS
1N
ORM
AL
LOU
DN
ESS
2IN
PUT
1(H
IGH
TRE
BLE)
INPU
T 2
(NO
RMA
L)
POW
ER IN
LET
FUSE
H.T
. FU
SEIM
PED
AN
CE
V6 5AR4
V3
12A
X7V
212
AX7
V112
AX7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
4 3
21
87
65
4 3
21
87
65
4 3
21
87
65
6
4 321
98
75
6
4 321
98
75
6
4 321
98
75
250KL
25KL
1MA
5KL
1MA
12
43
12
43
AA BB
12
43
12
43
ST
EP
15
ST
EP
16
12
43
12
43
Enla
rged
tosh
ow d
etai
lM
ount
jack
s ou
tsid
eon
the
fron
t pan
el
AA BB
AA BB
stew
mac
.co
m
13
©20
19
Stew
Mac
S
TE
P 8
Inst
all t
he
thre
e la
rge
tub
e so
cket
s w
ith
sp
rin
g r
etai
ner
sO
rien
t th
ese
eigh
t-p
in t
ube
sock
ets
so
that
pin
1 is
clo
sest
to
the
rear
pan
el o
f th
e ch
assi
s .
Use
4-4
0 x
3/8"
mac
hin
e sc
rew
s an
d lo
cknu
ts t
o m
ount
the
se s
ocke
ts o
n th
e ou
tsid
e of
the
cha
ssis
. Inc
lud
e a
sprin
g re
tain
er o
n th
e b
otto
m o
f ea
ch s
ocke
t to
pro
vid
e su
pp
ort f
or th
ese
thre
e tu
bes
w
hen
they
’re in
stal
led
late
r .
S
TE
P 9
Inst
all t
he
thre
e sm
all t
ub
e so
cket
sPo
sitio
n th
ese
nine
-pin
soc
kets
so
pin
1
is c
lose
st to
the
rear
pan
el o
f the
cha
ssis
. U
se t
wo
4-40
x 1
/4" m
achi
ne s
crew
s an
d lo
cknu
ts t
o m
ount
the
thr
ee r
emai
ning
tu
be
sock
ets .
S
TE
P 1
0
Inst
all t
he
H.T
. fu
se s
ock
etIn
stal
l the
hig
h-t
ensi
on fu
se so
cket
in th
e b
ack
pan
el .
S
TE
P 1
1
Inst
all t
he
po
wer
inp
ut
Inst
all
the
pow
er in
put
wit
h it
s ce
ntra
l gr
ound
lug
faci
ng th
e ch
assi
s op
enin
g .
S
TE
P 1
2
Inst
all t
he
ind
icat
or
lig
ht
Inst
all t
he in
dica
tor l
ight
in th
e fr
ont p
anel
an
d tw
ist t
he t
wo
lead
s to
geth
er .
Co
il th
ese
wir
es t
emp
ora
rily
to
kee
p
them
out
of
your
way
, sin
ce t
hey
won
’t b
e co
nnec
ted
until
late
r .
S
TE
P 1
3
Ad
d t
he
stan
db
y sw
itch
Mo
un
t th
e st
and
by
swit
ch u
sin
g t
he
switc
h m
ount
ing
nut .
Aft
er in
sert
ing
the
switc
h, p
lace
its
was
her o
n th
e th
read
ed
shaf
t bef
ore
addi
ng th
e nu
t .
S
TE
P 14
Inst
all t
he
rem
ain
ing
co
ntr
ol p
ots
Mou
nt th
e co
ntro
l pot
s so
thei
r thr
ee lu
gs
are
faci
ng
th
e ch
assi
s o
pen
ing
. W
hen
w
e re
fer t
o th
ese
lugs
as
left
or r
ight
, it’s
as
sum
ing
you’
re lo
okin
g at
the
pot
from
th
e sa
me
po
int
of
view
as
the
wir
ing
diag
ram
. M
ount
them
as
follo
ws:
Pres
ence
: 5KL
pot
Ba
ss: 1
MA
pot
Mid
dle
(mid
s): 2
5KL
pot
Tr
eble
: 250
KL p
ot
H
igh
Treb
le L
oudn
ess:
1M
A
S
TE
P 1
5
Wir
e th
e n
orm
al c
han
nel
inp
ut
jack
sU
se tw
o 4-
lug
jack
s fo
r the
inp
uts
on th
e n
orm
al c
han
nel
. Fo
r th
ese
step
s, w
e’ll
refe
r to
thes
e in
put
jack
s as
A a
nd B
.
Mo
un
t th
e ja
cks
tem
po
rari
ly o
n t
he
outs
ide
of th
e ch
assi
s, in
thei
r res
pec
tive
hole
s with
thei
r lug
s poi
ntin
g to
war
d th
e in
dica
tor l
ight
.
Mou
ntin
g th
e ja
cks
outs
ide
the
chas
sis
will
hol
d th
em in
pos
ition
and
giv
e yo
u ro
om to
do
the
tric
ky jo
b o
f wiri
ng th
em
up . A
fter
war
d, th
ey’ll
fit n
icel
y in
sid
e th
e ch
assi
s as
a p
re-w
ired
asse
mb
ly .
In b
uild
ing
th
is a
mp
, yo
u’ll
cu
t p
iece
s o
f w
ire
to m
ake
con
nec
tio
ns .
Th
ese
con
nec
tin
g w
ires
are
cal
led
ju
mp
ers,
an
d yo
u’ll
use
a lo
t of
the
m in
bui
ldin
g th
is a
mp .
Cut a
2" l
engt
h of
yel
low
wire
. Rem
ove
the
insu
latio
n to
cre
ate
a b
are
wire
jum
per
.
Bend
a s
mal
l hoo
k on
one
end
and
run
th
e lo
ng s
trai
ght
end
thro
ugh
lug
2 an
d lu
g 3
of ja
ck A
, and
thro
ugh
lug
2 an
d lu
g 3
of ja
ck B
.
Sold
er th
is ju
mp
er to
lug
3 of
jack
A .
S
TE
P 1
6
No
rmal
ch
ann
el ja
cks,
co
nti
nu
ed…
Run
one
lead
of a
1M
resi
stor
thro
ugh
lug
3 of
jack
B a
nd th
e ot
her l
ead
thro
ugh
lug
4 of
jack
B .
Sold
er th
e re
sist
or le
ad a
nd ju
mp
er le
ad
to lu
g 3
of ja
ck B
and
trim
aw
ay a
ny e
xces
s ju
mp
er a
nd re
sist
or le
ad .
Cut a
1" p
iece
of y
ello
w w
ire a
nd re
mov
e th
e in
sula
tio
n .
Ru
n t
his
bar
e ju
mp
er
thro
ugh
lug
1 an
d lu
g 2
of ja
ck B
. Sol
der
th
is ju
mp
er to
bot
h lu
gs .
Cut a
2" y
ello
w ju
mp
er a
nd w
rap
one
end
to
lug
4 of
jack
B . S
old
er th
e ot
her e
nd to
lu
g 1
of ja
ck A
.
Rem
ove
thes
e w
ired
-up
inp
ut ja
cks
and
mou
nt t
hem
in t
he s
ame
hole
s on
the
in
sid
e of
the
chas
sis .
(The
ir lu
gs a
re n
ow
faci
ng a
way
from
the
indi
cato
r lig
ht .)
stew
mac
.co
m
14
©20
19 S
tew
Mac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
IND
ICAT
OR
LIG
HT
PRES
ENCE
BASS
MID
DLE
TREB
LEH
IGH
TRE
BLE
LOU
DN
ESS
1N
ORM
AL
LOU
DN
ESS
2IN
PUT
1(H
IGH
TRE
BLE)
INPU
T 2
(NO
RMA
L)
POW
ER IN
LET
FUSE
H.T
. FU
SEIM
PED
AN
CE
V6 5AR4
V3
12A
X7V
212
AX7
V112
AX7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
4 3
21
87
65
4 3
21
87
65
4 3
21
87
65
6
4 321
98
75
6
4 321
98
75
6
4 321
98
75
1MA
1MA
25KL
250KL
1MA
5KL
12
43
12
43
12
43
12
43
AA BB
.1μF
12
43
12
43
ST
EP
17
ST
EP
18
12
43
12
43
Enla
rged
tosh
ow d
etai
lM
ount
jack
s ou
tsid
eon
the
fron
t pan
el
AA BB
AA BB
stew
mac
.co
m
15
©20
19
Stew
Mac
S
TE
P 1
7
Wir
e th
e h
igh
tre
ble
ch
ann
el in
pu
t ja
cks
Ag
ain,
use
tw
o 4-
lug
jac
ks w
hich
we’
ll re
fer t
o as
A a
nd B
.
As y
ou d
id w
ith th
e no
rmal
cha
nnel
jack
s,
asse
mb
le t
hes
e o
n t
he
ou
tsid
e o
f th
e ch
assi
s w
ith
thei
r lu
gs p
oint
ing
tow
ard
the
indi
cato
r lig
ht .
Cut a
2" l
engt
h of
yel
low
wire
. Rem
ove
the
insu
latio
n to
cre
ate
a b
are
wire
jum
per
.
Bend
a s
mal
l hoo
k on
one
end
and
run
th
e lo
ng s
trai
ght
end
thro
ugh
lug
2 an
d lu
g 3
of ja
ck A
, and
thro
ugh
lug
2 an
d lu
g 3
of ja
ck B
.
Sold
er th
is ju
mp
er to
lug
3 of
jack
A .
S
TE
P 1
8
Hig
h t
reb
le c
han
nel
jack
s,
con
tin
ued
…Ru
n on
e le
ad o
f a 1
M re
sist
or th
roug
h lu
g 3
of ja
ck B
and
the
othe
r lea
d th
roug
h lu
g 4
of ja
ck B
.
Sold
er th
e re
sist
or le
ad a
nd ju
mp
er le
ad
to lu
g 3
of ja
ck B
and
trim
aw
ay a
ny e
xces
s ju
mp
er a
nd re
sist
or le
ad .
Cut a
1" p
iece
of y
ello
w w
ire a
nd re
mov
e th
e in
sula
tio
n .
Ru
n t
his
bar
e ju
mp
er
thro
ugh
lug
1 an
d lu
g 2
of ja
ck B
. Sol
der
th
is ju
mp
er to
bot
h lu
gs .
Cut a
2" y
ello
w ju
mp
er a
nd w
rap
one
end
to
lug
4 of
jack
B . S
old
er th
e ot
her e
nd to
lu
g 1
of ja
ck A
.
Rem
ove
thes
e w
ired
-up
inp
ut ja
cks
and
mou
nt t
hem
in t
he s
ame
hole
s on
the
in
sid
e of
the
chas
sis .
(The
ir lu
gs a
re n
ow
faci
ng a
way
from
the
indi
cato
r lig
ht .)
S
TE
P 19
Ad
d t
wo
gro
un
d ju
mp
ers
Cut
one
1-3/
4" g
reen
jum
per
and
wra
p
on
e en
d t
o l
ug
2 o
f th
e h
igh
tre
ble
ch
anne
l jac
k A
. Sol
der
the
oth
er e
nd t
o lu
g 2
of th
e no
rmal
cha
nnel
jack
A .
Cut a
3" g
reen
jum
per
and
wra
p o
ne e
nd
to lu
g 2
of th
e hi
gh tr
eble
cha
nnel
jack
A .
Sold
er th
is ju
mp
er e
nd in
pla
ce w
ith th
e tw
o ot
her
jum
per
s al
read
y th
ere .
Tur
n th
e no
rmal
cha
nnel
loud
ness
pot
sha
ft
cloc
kwis
e to
its
zero
pos
ition
and
sol
der
th
e ot
her e
nd o
f thi
s ju
mp
er to
the
bac
k of
the
norm
al c
hann
el lo
udne
ss p
ot .
S
TE
P 2
0
Gro
un
d t
hre
e co
ntr
ol p
ots
Turn
all
pot
sha
fts
coun
terc
lock
wis
e to
th
eir
zero
pos
itio
n b
efor
e st
arti
ng
thi
s st
ep . T
his
is b
ecau
se y
ou’ll
be
app
lyin
g he
at to
thei
r cas
es, a
nd if
the
heat
ling
ers
too
long
it c
ould
cre
ate
an im
pre
ssio
n on
th
e w
iper
insi
de . T
his i
sn’t
a co
ncer
n if
the
pot
is in
the
zero
pos
ition
.
Cut
thre
e 1"
jum
per
s of
gre
en w
ire, p
ull
off th
eir i
nsul
atio
n, a
nd b
end
one
end
of
each
in to
a h
ook .
Star
tin
g w
ith
th
e n
orm
al c
han
ne
l lo
udne
ss p
ot s
old
er th
e ho
ok e
nd o
f the
ju
mp
er t
o th
e le
ft lu
g of
the
pot
. Sol
der
th
e st
raig
ht e
nd
of
this
jum
per
to
the
bac
k of
the
pot
.
Rep
eat
this
pro
cess
for
the
hig
h tr
eble
lo
udne
ss p
ot a
nd th
e m
ids
pot
.
S
TE
P 2
1
Ad
d t
wo
yel
low
jum
per
sC
ut
a 4"
yel
low
ju
mp
er .
Stri
p 3
/4"
of
insu
latio
n fr
om o
ne si
de . R
un th
is ju
mp
er
dow
n th
roug
h th
e m
iddl
e lu
g of
the
bas
s p
ot a
nd b
ack
up th
roug
h th
e rig
ht lu
g of
th
e b
ass
pot
. Sol
der
this
jum
per
to b
oth
lugs
of t
he b
ass
pot
. Rou
te th
e ot
her e
nd
of th
is ju
mp
er o
ver t
he m
ids p
ot a
nd w
rap
th
e ot
her e
nd th
roug
h th
e le
ft lu
g of
the
treb
le p
ot . D
on't
sold
er th
is e
nd y
et .
Cut a
3-1
/4" y
ello
w ju
mp
er a
nd so
lder
one
en
d to
the
left
lug
of th
e b
ass
pot
. Sol
der
th
e ot
her e
nd o
f thi
s ju
mp
er to
the
right
lu
g of
the
mid
s p
ot .
S
TE
P 2
2
Ad
d a
.1μ
F ca
pac
ito
rSo
lder
a .1
μF c
ap b
etw
een
the
left
lug
of
the
pre
senc
e p
ot a
nd t
he m
iddl
e lu
g of
th
e sa
me
pot
. Ben
d t
he c
apac
itor
lea
d fr
om t
he le
ft lu
g of
the
pot
to
the
bac
k of
the
pot
and
sol
der
it . T
rim a
way
any
ex
cess
lea
d a
t th
e m
idd
le l
ug
an
d t
he
bac
k of
the
pot
.
stew
mac
.co
m
16
©20
19 S
tew
Mac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
IND
ICAT
OR
LIG
HT
PRES
ENCE
BASS
MID
DLE
TREB
LEH
IGH
TRE
BLE
LOU
DN
ESS
1N
ORM
AL
LOU
DN
ESS
2IN
PUT
1(H
IGH
TRE
BLE)
INPU
T 2
(NO
RMA
L)
POW
ER IN
LET
FUSE
H.T
. FU
SEIM
PED
AN
CE
V6 5AR4
V3
12A
X7V
212
AX7
V112
AX7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
4 3
21
87
65
4 3
21
87
65
4 3
21
87
65
6
4 321
98
75
6
4 321
98
75
6
4 321
98
75
12
43
12
43
12
43
12
43
stew
mac
.co
m
17
©20
19
Stew
Mac
S
TE
P 2
3
Po
wer
tra
nsf
orm
er r
ed le
ads
Run
the
two
red
wire
s fr
om t
he p
ower
tr
ansf
orm
er t
o t
he
V6
rect
ifie
r tu
be
sock
et . T
rim
the
se w
ires
to
leng
th a
nd
sold
er o
ne t
o p
in 4
and
the
oth
er t
o p
in
6 . E
ither
wire
can
go
to e
ither
lug .
S
TE
P 2
4
Po
wer
tra
nsf
orm
er y
ello
w le
ads
Run
the
two
yello
w w
ires f
rom
the
pow
er
tran
sfo
rmer
to
th
e V
6 re
ctif
ier
tub
e so
cket
. Tri
m t
hese
wir
es t
o le
ngth
an
d so
lder
one
to
pin
2 a
nd t
he o
ther
to
pin
8 .
Eith
er w
ire c
an g
o to
eith
er lu
g
S
TE
P 2
5
Po
wer
tra
nsf
orm
er b
lack
an
d b
lack
/b
lue
lead
sRu
n th
e tw
iste
d p
air
of s
olid
bla
ck a
nd
stri
ped
bla
ck/b
lue
pow
er t
ran
sfo
rmer
le
ads
to th
e m
ains
fuse
soc
ket a
nd w
rap
th
em b
oth
to t
he le
ft lu
g . D
on't
sold
er
them
yet
.
S
TE
P 2
6
Po
wer
tra
nsf
orm
er b
lack
/yel
low
an
d b
lack
/wh
ite
lead
sRu
n t
he
twis
ted
pai
r of
str
iped
bla
ck/
yello
w a
nd
str
iped
bla
ck/w
hit
e p
ower
tr
ansf
orm
er le
ads
to t
he r
ight
lug
of t
he
pow
er s
witc
h an
d w
rap
the
m o
n to
the
lu
g . D
on't
sold
er th
em y
et .
S
TE
P 2
7
Po
wer
tra
nsf
orm
er r
ed/y
ello
w le
adR
un
th
e s
trip
ed
re
d/y
ell
ow
po
we
r tr
ansf
orm
er le
ad t
o th
e H
.T . f
use
sock
et,
cut i
t to
an a
ppro
pria
te le
ngth
, and
sold
er
it to
the
left
lug .
S
TE
P 2
8
Po
wer
tra
nsf
orm
er g
reen
/yel
low
le
adR
un
th
e st
rip
ed g
reen
/yel
low
po
wer
tr
an
sfo
rme
r le
ad
to
th
e t
wo
-lu
g g
rou
nd
ing
str
ip n
ext
to
th
e m
ain
s fu
se s
ock
et a
nd
sol
der
it
to t
he
cent
er
grou
ndin
g lu
g as
sho
wn .
S
TE
P 2
9
Inst
all o
ne
pil
ot-
lig
ht
lead
Cut
eith
er o
ne o
f the
pilo
t lig
ht le
ads
to
an a
pp
rop
riat
e le
ng
th a
nd
sol
der
it
to
the
right
lug
of t
he p
ower
sw
itch
alon
g w
ith th
e st
riped
bla
ck/y
ello
w a
nd st
riped
b
lack
/whi
te p
ower
tran
sfor
mer
lead
s .
S
TE
P 3
0
Inst
all t
he
oth
er p
ilo
t-li
gh
t le
adCu
t a
5" y
ello
w ju
mp
er to
be
conn
ecte
d to
the
othe
r pilo
t lig
ht le
ad . S
trip
3/4
" of
in
sula
tion
back
from
bot
h th
e ju
mp
er a
nd
the
pilo
t la
mp
lead
, tw
ist
the
bar
e w
ires
toge
ther
, and
sol
der
them
.
Slid
e 1"
of
1/8"
hea
t-sh
rink
tub
ing
over
th
e so
lder
join
t an
d ad
d he
at t
o cr
eate
el
ectr
ical
insu
lati
on o
ver
the
bar
e w
ire
of th
ese
sold
ered
lead
s .
Sold
er th
e fr
ee e
nd o
f thi
s ju
mp
er to
the
left
lug
of t
he m
ains
fus
e so
cket
alo
ng
with
the
pow
er tr
ansf
orm
er le
ads a
lread
y w
rap
ped
in p
lace
.
Use a
match
or lig
hter
to ins
ulate
wires
with
heat-s
hrink
tubing
stew
mac
.co
m
18
©20
19 S
tew
Mac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
IND
ICAT
OR
LIG
HT
PRES
ENCE
BASS
MID
DLE
TREB
LEH
IGH
TRE
BLE
LOU
DN
ESS
1N
ORM
AL
LOU
DN
ESS
2IN
PUT
1(H
IGH
TRE
BLE)
INPU
T 2
(NO
RMA
L)
POW
ER IN
LET
FUSE
H.T
. FU
SEIM
PED
AN
CE
V6 5AR4
V3
12A
X7V
212
AX7
V112
AX7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
4 3
21
87
65
6
4 321
98
75
6
4 321
98
75
6
4 321
98
75
4 3
21
87
65
4 3
21
87
65
12
43
12
43
12
43
12
43
stew
mac
.co
m
19
©20
19
Stew
Mac
S
TE
P 3
1
Ad
d t
wo
yel
low
jum
per
sCu
t one
14"
yel
low
jum
per
and
sold
er o
ne
end
to t
he r
ight
lug
of t
he p
ower
inp
ut .
Run
the
othe
r end
of t
his
jum
per
aro
und
the
outs
ide
wal
l of t
he c
hass
is a
nd so
lder
it
to th
e le
ft lu
g of
the
pow
er s
witc
h .
Cut o
ne 4
" jum
per
and
sol
der
one
end
to
the
left
lug
of th
e p
ower
inp
ut . S
olde
r the
ot
her
end
to t
he r
ight
lug
of t
he m
ains
fu
se s
ocke
t .
S
TE
P 3
2
Ad
d o
ne
gre
en ju
mp
erCu
t on
e 3-
1/4"
gre
en ju
mp
er a
nd s
old
er
one
end
in to
the
mid
dle
lug
of th
e p
ower
in
put
. Sol
der
the
othe
r end
to th
e le
ft lu
g of
the
two
-lug
grou
ndin
g st
rip c
lose
st to
th
e m
ains
fuse
soc
ket .
S
TE
P 3
3
Inst
all t
he
bia
s p
ot
Mou
nt t
he 1
0KL
bia
s p
ot in
the
floo
r of
th
e ch
assi
s as
sho
wn .
S
TE
P 3
4
Gro
un
d t
he
po
wer
tu
be
sock
ets
Cut
tw
o 3/
4" g
reen
jum
per
s an
d b
end
them
bo
th i
nto
a U
sh
ape .
Ad
d o
ne
jum
per
bet
wee
n V
5 p
in 1
an
d p
in 8
. So
lder
th
is j
um
per
to
pin
1 .
Ad
d t
he
othe
r ju
mp
er b
etw
een
V4 p
in 1
and
pin
8 .
Sol
der
this
jum
per
to p
in 8
.
Cut a
4" g
reen
jum
per
. Sol
der
one
end
to
V4 p
in 1
alo
ng w
ith t
he ju
mp
er in
pla
ce
and
wra
p th
e ot
her e
nd to
V5
pin
8 .
Cut a
3" g
reen
jum
per
and
sold
er o
ne e
nd
to V
5 p
in 8
with
the
oth
er t
wo
jum
per
s .
Sold
er th
e ot
her e
nd o
f thi
s jum
per
to o
ne
of th
e lu
gs o
n th
e ne
arby
gro
undi
ng st
rip .
S
TE
P 3
5
Ad
d t
wo
470
Ω 2
W r
esis
tors
Thes
e re
sist
ors
pro
tect
the
pow
er t
ubes
an
d t
he
ou
tpu
t tr
ansf
orm
er,
and
in
doi
ng th
is c
an g
et e
xtre
mel
y ho
t . Fo
r thi
s re
ason
, the
y ne
ed to
be
mou
nted
up
and
aw
ay fr
om th
e tu
be
sock
ets
by 1
/2” .
Wra
p o
ne
lead
of
the
firs
t 47
0 Ω
2W
re
sist
or to
pin
4 o
f V5
and
wra
p th
e ot
her
lead
to p
in 6
of V
5, s
tand
ing
it up
off
the
tub
e so
cket
1/2
" . So
lder
the
lead
wra
pped
to
pin
4 .
Wra
p o
ne
lead
of
the
seco
nd
470
Ω
resi
stor
to p
in 4
of V
4 an
d w
rap
the
othe
r le
ad to
pin
6 o
f V4,
sta
ndin
g it
up o
ff th
e tu
be
sock
et 1
/2" .
Sold
er th
e le
ad w
rapp
ed
to p
in 4
.
S
TE
P 3
6
Ad
d o
ne
yell
ow
jum
per
Cut o
ne 4
" yel
low
jum
per
. Sol
der o
ne e
nd
of th
e ju
mp
er to
V5
pin
6 w
ith th
e re
sist
or
lead
alre
ady
in p
lace
. Wra
p th
e ot
her e
nd
to V
4 p
in 6
, but
don
't so
lder
it y
et .
stew
mac
.co
m
20
©
2019
Ste
wM
ac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
IND
ICAT
OR
LIG
HT
PRES
ENCE
BASS
MID
DLE
TREB
LEH
IGH
TRE
BLE
LOU
DN
ESS
1N
ORM
AL
LOU
DN
ESS
2IN
PUT
1(H
IGH
TRE
BLE)
INPU
T 2
(NO
RMA
L)
POW
ER IN
LET
FUSE
H.T
. FU
SEIM
PED
AN
CE
V6 5AR4
V3
12A
X7V
212
AX7
V112
AX7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
4 3
21
87
65
6
4 321
98
75
6
4 321
98
75
6
4 321
98
75
4 3
21
87
65
4 3
21
87
65
12
43
12
43
12
43
12
43
stew
mac
.co
m
21
©
2019
St
ewM
ac
S
TE
P 3
7
Inst
all t
he
hea
ter
wir
esTu
bes
requ
ire a
6 .3
V A
C c
urre
nt to
pow
er
thei
r fi
lam
ents
, w
hic
h a
re a
lso
cal
led
"hea
ters
" in
the
am
p w
orld
. Thi
s cu
rren
t is
pro
vid
ed b
y th
e p
ower
tra
nsf
orm
er
thro
ugh
the
gree
n le
ads .
The
Briti
sh st
yle
of ru
nnin
g he
ater
wire
s is
to tu
ck th
em in
to th
e b
otto
m b
ack
corn
er
of t
he c
hass
is . K
eep
ing
the
wire
s tu
cked
in
to th
e b
ack
corn
er o
f the
cha
ssis
, aw
ay
from
the
sig
nal c
arry
ing
wire
s, p
reve
nts
the
AC
cur
rent
in th
ese
heat
er w
ires f
rom
b
leed
ing
60hz
hum
into
you
r sig
nal .
S
TE
P 3
8
Co
nn
ect
to s
ock
et V
5Ru
n th
e p
ower
tra
nsfo
rmer
gre
en w
ires
to so
cket
V5,
kee
ping
them
dow
n as
clo
se
to th
e ch
assi
s as
pos
sib
le .
Cut
two
8" h
eate
r w
ires,
one
whi
te a
nd
on
e b
lack
. Tw
ist
them
to
get
her
ver
y ti
gh
tly,
lea
vin
g a
bo
ut
1" o
f th
e en
ds
un
twis
ted
. Jo
in t
he
wh
ite
jum
per
to
eith
er o
f the
gre
en p
ower
supp
ly le
ads b
y tw
istin
g th
e en
ds to
geth
er . J
oin
the
bla
ck
jum
per
to th
e ot
her g
reen
lead
.
Sold
er t
he
pai
r w
ith
th
e w
hite
wir
e to
p
in 2
of
sock
et V
5 . S
old
er t
he p
air
with
th
e b
lack
wire
to p
in 7
of s
ocke
t V5 .
Ben
d th
ese
wire
s in
to t
he b
ack
corn
er o
f th
e ch
assi
s an
d t
hen
ben
d t
he
bla
ck-a
nd
-w
hite
pai
r at a
90°
ang
le to
war
d so
cket
V4 .
S
TE
P 3
9
Co
nn
ect
to s
ock
et V
4Cu
t tw
o 7"
hea
ter
wire
s, o
ne w
hite
and
on
e b
lack
. Tw
ist t
hem
tigh
tly
toge
ther
.
Twis
t th
e en
d o
f th
e w
hite
wir
e to
th
e w
hite
jum
per
com
ing
from
V5 .
Tw
ist t
he
bla
ck w
ire w
ith th
e b
lack
jum
per
com
ing
from
V5 .
Sold
er t
he w
hite
pai
r on
to p
in 2
of
V4 .
Sold
er th
e b
lack
pai
r ont
o p
in 7
. Ben
d th
e w
ires
into
the
bac
k co
rner
of t
he c
hass
is,
and
on to
war
d so
cket
V3 .
Sold
er th
e w
hite
pai
r to
pin
2 of
sock
et V
4 .
Sold
er th
e b
lack
pai
r to
pin
7 o
f soc
ket V
4 .
Bend
thes
e w
ires
into
the
bac
k co
rner
of
the
chas
sis a
nd th
en b
end
the
bla
ck-a
nd-
whi
te p
air a
t a 9
0° a
ngle
tow
ard
sock
et V
3 .
Use t
his he
ater-w
ire tec
hnique
to
minimi
ze the
hum c
aused
by AC
voltag
eTh
e tw
iste
d gr
een
wire
s fro
m th
e p
ower
tran
sfor
mer
car
ry A
C v
olta
ge to
th
e he
atin
g fil
amen
ts in
the
tub
es . T
his
volt
age
will
cau
se y
our a
mp
to
hum
if th
ese
wire
s are
allo
wed
to ru
n to
o cl
ose
to si
gnal
-car
ryin
g w
ires .
Twis
t th
e w
ires
tig
htl
y to
get
her
This
tw
ist
isn’
t fo
r lo
oks;
it’s
an
imp
orta
nt h
um-c
ance
lling
tec
hniq
ue
to r
educ
e no
ise
in y
our
amp .
It w
orks
in a
way
sim
ilar
to t
he o
pp
o-
site
-wou
nd c
oils
in a
hum
buc
king
pic
kup .
Ro
ute
th
em a
way
To k
eep
tw
iste
d he
ater
wire
s aw
ay f
rom
sig
nal-
carr
ying
wire
s, r
oute
th
em in
to th
e b
ack
edge
of t
he fl
oor o
f the
cha
ssis
. Giv
e th
em a
sha
rp
right
ang
le b
end
tow
ard
the
next
sock
et a
nd a
noth
er sh
arp
ben
d b
ack
dow
n to
tha
t so
cket
. Thi
s ke
eps
them
shi
eld
ed a
nd a
way
from
sig
nal
carr
ying
wire
s .
stew
mac
.co
m
22
©
2019
Ste
wM
ac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
IND
ICAT
OR
LIG
HT
PRES
ENCE
BASS
MID
DLE
TREB
LEH
IGH
TRE
BLE
LOU
DN
ESS
1N
ORM
AL
LOU
DN
ESS
2IN
PUT
1(H
IGH
TRE
BLE)
INPU
T 2
(NO
RMA
L)
POW
ER IN
LET
FUSE
H.T
. FU
SEIM
PED
AN
CE
V6 5AR4
V3
12A
X7V
212
AX7
V112
AX7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
6
4 321
98
75
6
4 321
98
75
6
4 321
98
75
4 3
21
87
65
4 3
21
87
65
4 3
21
87
65
12
43
12
43
12
43
12
43
stew
mac
.co
m
23
©
2019
St
ewM
ac
S
TE
P 4
0
Co
nn
ect
to s
ock
et V
3O
n so
cket
s V3
, V2,
and
V1
you
will
nee
d to
join
pin
s 4
and
5 to
geth
er . O
n th
ese
thre
e so
cket
s, g
entl
y tw
ist
pin
s 4
and
pin
5 t
owar
d ea
ch o
ther
so
thei
r ey
elet
s lin
e up
. Be
very
car
eful
whi
le d
oing
thi
s as
thes
e p
ins
are
del
icat
e .
Cut
two
7" h
eate
r w
ires,
one
whi
te a
nd
one
bla
ck . T
wis
t the
m ti
ghtl
y to
geth
er .
Twis
t the
end
of t
he w
hite
wire
toge
ther
w
ith t
he w
hite
jum
per
com
ing
from
V4 .
Tw
ist t
he b
lack
wire
with
the
blac
k ju
mp
er
com
ing
from
V4 .
Sold
er t
he w
hite
pai
r to
com
bin
ed p
ins
4+5
on V
3 an
d so
lder
the
bla
ck p
air t
o V3
pi
n 9 .
Ben
d th
e w
ires i
n to
the
bac
k co
rner
of
the
chas
sis,
and
on
tow
ard
sock
et V
2 .
S
TE
P 4
1
Co
nn
ect
to s
ock
et V
2Cu
t tw
o 7"
hea
ter
wire
s, o
ne w
hite
and
on
e b
lack
. Tw
ist t
hem
tigh
tly
toge
ther
.
Twis
t the
end
of t
he w
hite
wire
toge
ther
w
ith t
he w
hite
jum
per
com
ing
from
V3 .
Tw
ist t
he b
lack
wire
with
the
blac
k ju
mp
er
com
ing
from
V3 .
Sold
er t
he w
hite
pai
r to
com
bin
ed p
ins
4+5
on V
2 an
d so
lder
the
bla
ck p
air t
o V2
pi
n 9 .
Ben
d th
e w
ires i
n to
the
bac
k co
rner
of
the
chas
sis,
and
on
tow
ard
sock
et V
1 .
S
TE
P 4
2
Co
nn
ect
to s
ock
et V
1Ru
n th
e bl
ack-
and-
whi
te tw
iste
d pa
ir in
to
the
bac
k co
rner
of t
he c
hass
is a
nd to
war
d V1
. Sol
der
the
bla
ck w
ire to
V1
pin
9 a
nd
sold
er th
e w
hite
wire
to V
1 p
in 4
+5 .
Car
eful
ly in
spec
t ea
ch s
old
er jo
int
from
th
is h
eate
r w
ire
inst
alla
tio
n a
nd
on
ce
the
sold
er jo
ints
hav
e co
oled
pus
h yo
ur
heat
er w
ires
in to
the
floor
of t
he c
hass
is
and
in t
o th
e b
ack
corn
er o
f th
e ch
assi
s as
muc
h as
you
can
.
S
TE
P 4
3
Co
nn
ect
the
ou
tpu
t tr
ansf
orm
er's
b
lue
lead
Rout
e th
e b
lue
outp
ut t
rans
form
er le
ad
as s
how
n on
the
wiri
ng d
iagr
am, a
long
th
e flo
or o
f th
e ch
assi
s, t
o p
in 3
of
the
V5 s
ocke
t . Ro
ute
it lik
e th
is b
ecau
se it
is
a si
gnal
car
ryin
g w
ire a
nd n
eeds
to
be
kep
t aw
ay f
rom
the
hea
ter
wire
s . C
ut it
to
an
ap
pro
pri
ate
len
gth
an
d s
old
er i
t to
V5
pin
3 .
S
TE
P 4
4
Co
nn
ect
the
ou
tpu
t tr
ansf
orm
er's
p
rim
ary
bro
wn
lead
Fin
d t
he
bro
wn
ou
tpu
t tr
ansf
orm
er
lea
d t
hat
is
com
ing
th
rou
gh
th
e sa
me
gro
mm
eted
ho
le a
s th
e o
utp
ut
tran
sfor
mer
blu
e an
d re
d le
ads .
Run
this
b
row
n ou
tput
tran
sfor
mer
lead
as s
how
n on
the
wiri
ng d
iagr
am, a
long
the
floor
of
the
chas
sis,
to p
in 3
of t
he V
4 so
cket
. Cut
it
to a
n ap
pro
pria
te le
ngth
and
sol
der
it
to V
4 p
in 3
.
stew
mac
.co
m
24
©20
19 S
tew
Mac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
IND
ICAT
OR
LIG
HT
PRES
ENCE
BASS
MID
DLE
TREB
LEH
IGH
TRE
BLE
LOU
DN
ESS
1N
ORM
AL
LOU
DN
ESS
2IN
PUT
1(H
IGH
TRE
BLE)
INPU
T 2
(NO
RMA
L)
POW
ER IN
LET
FUSE
H.T
. FU
SEIM
PED
AN
CE
V6 5AR4
V3
12A
X7V
212
AX7
V112
AX7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
6
4 321
98
75
6
4 321
98
75
6
4 321
98
75
1
23
4
4 3
21
87
65
4 3
21
87
65
4 3
21
87
65
12
43
12
43
12
43
12
43
stew
mac
.co
m
25
©
2019
St
ewM
ac
S
TE
P 4
5
Term
inat
e th
e o
utp
ut
tran
sfo
rmer
's
seco
nd
ary
bro
wn
lead
Fin
d t
he
bro
wn
ou
tpu
t tr
ansf
orm
er
lea
d t
hat
is
com
ing
th
rou
gh
th
e sa
me
gro
mm
eted
ho
le a
s th
e o
utp
ut
tran
sfor
mer
's y
ello
w, o
rang
e, g
reen
, and
b
lack
lead
s . R
un t
his
bro
wn
lead
to
the
two
-lug
grou
ndin
g st
rip n
ear
the
mai
ns
fuse
soc
ket .
Rout
e th
is le
ad a
s sh
own
on
the
wiri
ng d
iagr
am .
Sold
er th
is b
row
n le
ad to
the
unco
nnec
ted
lug
of th
is s
trip
. Thi
s is
an
unus
ed o
utp
ut
tran
sfor
mer
lead
, whi
ch w
ill c
arry
unu
sed
volt
age .
It n
eeds
to b
e sa
fely
term
inat
ed
and
in
sula
ted
. O
nce
yo
ur
sold
er j
oin
t co
ols,
cov
er it
with
1/2
" len
gth
of 1
/8" h
eat
shrin
k tu
bin
g . A
s the
hea
t shr
ink
tub
ing
is
cool
ing,
pin
ch th
e to
p o
f it w
ith p
liers
to
secu
re th
e so
lder
join
t, sa
fely
term
inat
ing
this
lead
.
S
TE
P 4
6
Ou
tpu
t tr
ansf
orm
er r
ed le
ad +
filt
er
cho
ke le
adTw
ist
the
outp
ut t
rans
form
er's
red
lead
w
ith e
ither
one
of t
he b
lack
filte
r ch
oke
lead
s . R
un t
hese
lead
s to
the
left
lug
of
the
stan
dby
switc
h an
d cu
t th
em t
o an
ap
pro
pria
te le
ngth
. Sol
der
the
m t
o th
e le
ft lu
g of
the
stan
dby
switc
h .
S
TE
P 4
7
Gro
un
d t
he
ou
tpu
t tr
ansf
orm
er's
b
lack
lead
Ru
n t
he
bla
ck w
ire
fro
m t
he
ou
tpu
t tr
ansf
orm
er to
the
3-lu
g gr
ound
ing
strip
ne
ar V
5 . T
rim it
to le
ngth
and
sol
der
it to
th
e rig
ht lu
g of
the
strip
.
S
TE
P 4
8
Ad
d o
ne
gre
en ju
mp
erCu
t one
2" g
reen
jum
per
. Sol
der
one
end
of
this
jum
per
to th
e rig
ht lu
g of
the
H .T
. fu
se s
ocke
t . So
lder
the
oth
er e
nd o
f thi
s ju
mp
er t
o th
e le
ft lu
g of
the
gro
undi
ng
strip
nex
t to
V5 .
S
TE
P 4
9
Ad
d t
wo
yel
low
jum
per
sCu
t tw
o 1"
yel
low
jum
per
s .
Use
one
to
conn
ect
pin
3 a
nd p
in 8
of
sock
et V
1 . S
old
er it
to p
in 3
onl
y .
Use
the
othe
r to
conn
ect p
in 3
and
pin
8
of s
ocke
t V3 .
Sol
der
it to
pin
3 o
nly .
S
TE
P 5
0
Ad
d t
wo
mo
re y
ello
w ju
mp
ers
Cut t
wo
7" y
ello
w ju
mp
ers .
Sold
er o
ne ju
mp
er to
V6
pin
6 a
nd ro
ute
it un
der
the
grou
ndin
g st
rip n
ear V
5 an
d to
war
d t
he
gro
mm
eted
ho
le w
ith
th
e re
d, b
lue,
and
bro
wn
outp
ut tr
ansf
orm
er
lead
s . L
eave
it
ther
e fo
r n
ow, y
ou'll
be
conn
ectin
g it
to th
e tu
rret
boa
rd la
ter .
Sold
er t
he o
ther
jum
per
to
pin
8 o
f V6
an
d r
ou
te i
t b
etw
een
th
e si
de
wal
l o
f th
e ch
assi
s an
d t
he p
ower
tra
nsfo
rmer
to
war
d th
e p
ower
sw
itch .
Lea
ve th
is o
ne
here
for n
ow, t
oo . Y
ou'll
be
conn
ectin
g it
to a
filte
r cap
sho
rtly
.
S
TE
P 5
1
Ad
d a
yel
low
jum
per
+ o
ne
resi
sto
rCu
t one
2" y
ello
w ju
mp
er . S
olde
r one
end
to
V2
pin
7 . R
oute
the
jum
per
aro
und
the
outs
ide
of th
e so
cket
and
wra
p th
e ot
her
end
to p
in 1
of t
he s
ame
sock
et .
Ad
d a
100k
res
isto
r b
etw
een
pin
1 a
nd
pin
6 o
f soc
ket V
2 . S
olde
r the
resi
stor
lead
to
pin
1 a
long
with
the
jum
per
alre
ady
in
pla
ce . L
eave
the
oth
er e
nd u
nsol
der
ed .
Trim
any
exc
ess
lead
.
S
TE
P 5
2
Inst
all t
he
imp
edan
ce s
wit
chM
ount
th
e im
ped
ance
sel
ecto
r sw
itch
as
sho
wn
in t
he d
iagr
am, w
ith t
he t
wo
mid
dle
lugs
faci
ng u
p .
Ther
e is
no
ho
le i
n t
he
chas
sis
for
the
tang
was
her
incl
uded
wit
h th
is s
witc
h,
so s
imp
ly fl
ip t
he w
ashe
r so
the
tan
g is
fa
cing
aw
ay fr
om th
e ch
assi
s w
all .
S
TE
P 5
3
Co
nn
ect
the
imp
edan
ce s
wit
chTh
e im
ped
ance
sel
ecto
r sw
itch
allo
ws
you
to se
t the
am
plifi
er’s
outp
ut to
mat
ch
the
spea
ker c
abin
et y
ou w
ill u
se .
Cu
t th
e o
utp
ut
tran
sfo
rmer
’s t
wis
ted
oran
ge, g
reen
, and
yel
low
wire
s to
leng
th
for c
onne
ctin
g to
the
imp
edan
ce se
lect
or
switc
h .
Sold
er t
he o
rang
e w
ire t
o th
e rig
ht lu
g (lu
g 1
in t
he d
iagr
am) .
Sold
er t
he g
reen
w
ire t
o lu
g 2,
and
the
yel
low
wire
to
lug
3 . T
he le
ft lu
g (4
) is
emp
ty a
t thi
s p
oint
.
1. S
olde
r2.
Cov
er w
ithhe
at-s
hrin
k tu
bin
g3.
Hea
t and
fo
ld o
ver
stew
mac
.co
m
26
©
2019
Ste
wM
ac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
IND
ICAT
OR
LIG
HT
PRES
ENCE
BASS
MID
DLE
TREB
LEH
IGH
TRE
BLE
LOU
DN
ESS
1N
ORM
AL
LOU
DN
ESS
2IN
PUT
1(H
IGH
TRE
BLE)
INPU
T 2
(NO
RMA
L)
POW
ER IN
LET
FUSE
H.T
. FU
SEIM
PED
AN
CE
V6 5AR4
V3
12A
X7V
212
AX7
V112
AX7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
D C
-
B A
-
4 3
21
87
65
4 3
21
87
65
4 3
21
87
65
6
4 321
98
75
6
4 321
98
75
6
4 321
98
75
12
43
12
43
12
43
12
43
.047μF
stew
mac
.co
m
27
©20
19
Stew
Mac
S
TE
P 5
4
Mo
un
t th
e fi
lter
cap
sTh
e fi
lter
cap
acit
ors
are
hel
d t
o t
he
chas
sis
wit
h m
ou
nti
ng
cla
mp
s . T
hes
e cl
amps
att
ach
to th
e ca
pac
itor o
n th
e en
d op
pos
ite th
e lu
gs, a
nd a
re th
en m
ount
ed
to t
he c
hass
is u
sing
6-3
2 x
1/2"
scr
ews
and
nuts
. Pos
ition
the
cla
mp
so
you
can
mou
nt t
he
cap
acit
or’s
neg
ativ
e (–
) lu
g fa
cing
up .
The
tab
s o
n t
he
filt
er c
ap m
ou
nti
ng
clam
ps
will
stic
k ou
t ab
ove
the
edge
of
the
chas
sis .
Use
nee
dle
nos
e p
liers
to
ben
d th
em d
own
so th
ey a
re n
ot st
icki
ng
up a
bov
e th
e ed
ge o
f the
cha
ssis
.
Thes
e tw
o fil
ter
cap
s w
ill b
e re
ferr
ed t
o as
the
fron
t fil
ter
cap
and
the
bac
k fil
ter
cap,
and
thei
r pos
itive
lugs
are
ass
igne
d th
e le
tter
s A
-D fo
r cla
rity .
S
TE
P 5
5
Gro
un
d t
he
filt
er c
aps
Cut
a 2
-1/2
" g
reen
jum
per
. So
lder
on
e en
d of
this
jum
per
to th
e b
ack
filte
r cap
's
nega
tive
(-) lu
g . W
rap
the
othe
r end
of t
his
jum
per
to
the
fron
t fil
ter
cap'
s ne
gativ
e lu
g b
ut d
on't
sold
er it
yet
.
Cut a
4" g
reen
jum
per
. Sol
der
one
end
of
this
jum
per
to
fron
t fil
ter
cap'
s ne
gativ
e lu
g . S
old
er t
he o
ther
end
of t
he ju
mp
er
to o
ne o
f the
lugs
of t
he g
roun
ding
str
ip
und
er th
e p
rese
nce
pot
.
S
TE
P 5
6
Co
nn
ect
on
e ju
mp
erFi
nd th
e 7"
yel
low
jum
per
att
ache
d to
pin
8
of s
ocke
t V6 .
Wra
p th
e fr
ee e
nd o
f tha
t ju
mp
er to
lug
D o
n th
e fr
ont fi
lter c
ap b
ut
don
’t so
lder
it y
et .
S
TE
P 5
7
Ad
d o
ne
jum
per
Cut o
ne 1
-3/4
" yel
low
jum
per
and
sol
der
on
e en
d to
lug
D o
f th
e fr
ont
filte
r ca
p
alon
g w
ith th
e ju
mp
er a
lread
y w
rap
ped
to
tha
t lu
g . W
rap
the
oth
er e
nd o
f th
is
jum
per
to ri
ght l
ug o
f the
stan
dby
switc
h b
ut d
on't
sold
er it
yet
.
S
TE
P 5
8
Ad
d o
ne
cap
Add
1" o
f 1/1
6" h
eat-
shrin
k tu
bin
g to
eac
h le
ad o
f a .0
47μF
cap
acito
r . A
pp
ly h
eat t
o sh
rink
the
tub
ing
to th
e le
ad . S
old
er o
ne
lead
to th
e rig
ht lu
g of
the
stan
dby
switc
h al
ong
with
the
jum
per
alre
ady
in p
lace
. So
lder
the
othe
r lea
d of
this
cap
acito
r to
the
grou
ndin
g st
rip u
nder
the
pre
senc
e p
ot .
Sto
p a
nd
insp
ect
you
r w
ork
This
is a
goo
d tim
e to
ste
p a
way
from
the
pro
ject
for
a f
ew m
inut
es . T
ake
a b
reak
b
efor
e re
view
ing
your
wor
k fo
r err
ors .
Whe
n yo
u’re
read
y to
go
at it
aga
in, v
ery
care
fully
wal
k th
roug
h ev
ery
conn
ectio
n yo
u’v
e m
ade
so f
ar . W
hen
eve
ryth
ing
chec
ks o
ut, y
ou’re
rea
dy
to m
ove
on t
o th
e tu
rret
boa
rd .
STOP
Be sus
piciou
s The
re's a
mistak
e, and
you’re
gonna
find it!
stew
mac
.co
m
28
©
2019
Ste
wM
ac
2
123 52
5150
4948
4746
4544
4342
4140
3938
37
2824
26
3033
27 35
2931
3225
34
36
34
56
78
910
1112
1314
1516
1718
1920
2122
250μF
.022μF
.022μF
500pF
250
stew
mac
.co
m
29
©20
19
Stew
Mac
Wra
pp
ing
par
ts o
nto
th
e tu
rret
bo
ard
You
’re r
ead
y to
sta
rt p
utt
ing
par
ts o
n th
e tu
rret
bo
ard
. In
th
ese
step
s, y
ou’ll
w
rap
the
lead
s on
to t
he t
urre
ts w
ithou
t so
lder
ing,
and
the
sol
der
will
be
add
ed
late
r . Th
is a
llow
s yo
u to
che
ck y
our w
ork
and
mak
e co
rrec
tio
ns
wit
ho
ut
hav
ing
to u
ndo
sold
er jo
ints
. Id
eally
, you
sol
der
ea
ch jo
int o
nly
once
.
S
TE
P 5
9
Wra
p a
n 8
20Ω
res
isto
rW
rap
an
820Ω
res
isto
r b
etw
een
turr
ets
23 a
nd 5
2 .
S
TE
P 6
0
Ad
d a
250
μF
bip
ola
r el
ectr
oly
tic
cap
acit
or
+ t
wo
jum
per
sN
orm
ally
ele
ctro
lyti
c ca
pac
ito
rs a
re
pol
ariz
ed . H
owev
er, t
his
one
is b
ipol
ar
mea
nin
g i
t ca
n b
e in
stal
led
in
eit
her
di
rect
ion .
Wra
p o
ne le
ad to
turr
et 2
3 an
d th
e ot
her l
ead
to tu
rret
52 .
Ad
d a
2-1/
2" y
ello
w ju
mp
er to
turr
et 5
2 .
Ad
d a
3" g
reen
jum
per
to tu
rret
23 .
S
TE
P 6
1
Ad
d t
wo
res
isto
rsA
dd
one
68k
resi
stor
bet
wee
n tu
rret
s 22
an
d 34
.
Add
ano
ther
68k
resi
stor
bet
wee
n tu
rret
s 21
and
34 .
S
TE
P 6
2
Ad
d t
hre
e ju
mp
ers
Cut t
wo
2" y
ello
w ju
mp
ers .
Ad
d th
e fir
st ju
mp
er to
turr
et 2
2 .
Ad
d th
e se
cond
jum
per
to tu
rret
21 .
Ad
d a
4-1/
2" y
ello
w ju
mp
er t
o tu
rret
34 .
Ru
n t
his
ju
mp
er s
trai
gh
t d
own
to
th
e b
otto
m o
f th
e tu
rret
boa
rd a
nd b
end
it ov
er t
he e
dge
of t
he b
oard
to
keep
it in
p
lace
.
S
TE
P 6
3
Ad
d fo
ur
resi
sto
rsA
dd
one
68k
resi
stor
bet
wee
n tu
rret
s 19
an
d 26
.
Add
ano
ther
68k
resi
stor
bet
wee
n tu
rret
s 18
and
26 .
Ad
d o
ne 1
00k
resi
stor
bet
wee
n tu
rret
s 33
and
50 .
Ad
d a
no
ther
10
0k
resi
sto
r b
etw
een
turr
ets
33 a
nd 5
1 .
S
TE
P 6
4
Ad
d t
wo
cap
acit
ors
Ad
d a
.022
μF c
apac
itor
bet
wee
n tu
rret
s 20
and
51 .
Thi
s an
d th
e fo
llow
ing
yello
w
cap
acit
ors
are
no
t p
ola
rize
d,
so y
ou
can
inst
all t
hem
in e
ither
dire
ctio
n . W
e re
com
men
d fa
cing
them
all
in th
e sa
me
dir
ecti
on
, m
akin
g t
hei
r p
rin
ted
sp
ecs
easy
to re
ad .
Ad
d an
othe
r .0
22μF
cap
acito
r b
etw
een
turr
ets
17 a
nd 5
0 .
S
TE
P 6
5
Ad
d fo
ur
jum
per
sCu
t tw
o 2"
yel
low
jum
per
s .
Ad
d th
e fir
st ju
mp
er to
turr
et 1
9 .
Ad
d th
e se
cond
jum
per
to tu
rret
18 .
Add
a 5
-1/2
" yel
low
jum
per
to tu
rret
20 .
Ad
d a
6-1/
2" y
ello
w ju
mp
er to
turr
et 1
7 .
S
TE
P 6
6
Ad
d t
wo
mo
re ju
mp
ers
Ad
d a
3-1/
2" y
ello
w ju
mp
er to
turr
et 5
1 .
Ad
d a
2-1/
2" y
ello
w ju
mp
er to
turr
et 5
0 .
S
TE
P 6
7
Ad
d t
wo
res
isto
rs +
on
e ca
pac
ito
rA
dd
a 2
70k
resi
sto
r b
etw
een
tu
rret
s 16
and
25 .
Ad
d a
270
k re
sist
or
bet
wee
n t
urr
ets
15 a
nd 2
5 .
Ad
d a
500
pF
cap
bet
wee
n tu
rret
s 15
an
d 25
.
S
TE
P 6
8
Ad
d t
hre
e ju
mp
ers
Ad
d a
4-1/
2" y
ello
w ju
mp
er to
turr
et 1
6 .
Ad
d a
6" y
ello
w ju
mp
er to
turr
et 1
5 .
Ad
d a
6" y
ello
w ju
mp
er to
turr
et 2
5 .
S
TE
P 6
9
Ad
d t
wo
res
isto
rs w
ith
ext
ensi
on
sCu
t one
1" y
ello
w ju
mp
er a
nd re
mov
e th
e in
sula
tion .
Wra
p a
nd s
old
er t
his
jum
per
ar
ound
one
lead
of
an 8
20Ω
res
isto
r to
ex
tend
the
lead
of t
he re
sist
or . D
oing
this
w
ill a
llow
the
res
isto
r to
rea
ch b
etw
een
turr
ets
14 a
nd 4
9 .
Add
this
820
Ω re
sist
or w
ith th
e ex
tens
ion
bet
wee
n tu
rret
s 14
and
49 .
Cut a
noth
er 1
" yel
low
jum
per
and
rem
ove
the
insu
lati
on
. W
rap
an
d s
old
er t
his
ju
mp
er a
roun
d on
e le
ad o
f a 1
00K
resi
stor
to
ext
end
the
lead
of t
he re
sist
or . A
dd th
is
resi
stor
bet
wee
n tu
rret
s 14
and
48 .
S
TE
P 7
0
Ad
d o
ne
cap
acit
or
+ t
hre
e ju
mp
ers
Ad
d a
25
0p
F Si
lve
r M
ica
cap
acit
or
bet
wee
n tu
rret
s 32
and
48 .
Ad
d a
3" y
ello
w ju
mp
er to
turr
et 4
9 .
Ad
d a
2-1/
2" y
ello
w ju
mp
er to
turr
et 4
8 .
Ad
d an
8"
jum
per
to
turr
et 3
2 . R
un t
his
turr
et u
p t
owar
d t
he
top
of
the
boa
rd
and
ben
d it
over
the
ed
ge o
f th
e b
oard
to
kee
p it
in p
lace
.
Ad
d a
3" g
reen
jum
per
to tu
rret
14 .
stew
mac
.co
m
30
©
2019
Ste
wM
ac
2
123 52
5150
4948
4746
4544
4342
4140
3938
37
2824
26
3033
27 35
2931
3225
34
36
34
56
78
910
1112
1314
1516
1718
1920
2122
.022μF
.022μF
.022μF
.1μF
.1μF
.1μF
47
5W 1K
stew
mac
.co
m
31
©
2019
St
ewM
ac
S
TE
P 7
1
Ad
d o
ne
resi
sto
r +
tw
o c
apac
ito
rsA
dd
a 5
6k r
esis
tor
bet
wee
n t
urre
ts 4
7 an
d 48
.
Ad
d a
.022
uF c
apac
itor
bet
wee
n tu
rret
s 13
and
47 .
Ad
d an
othe
r .0
22uF
cap
acito
r b
etw
een
turr
ets
12 a
nd 4
7 .
S
TE
P 7
2
Ad
d t
wo
jum
per
s A
dd
a 7-
1/2"
yel
low
jum
per
to tu
rret
13 .
Ad
d an
8" y
ello
w ju
mp
er to
turr
et 1
2 .
S
TE
P 7
3
Ad
d o
ne
resi
sto
r +
on
e ju
mp
erCu
t one
1" y
ello
w ju
mp
er a
nd re
mov
e th
e in
sula
tion .
Wra
p a
nd s
old
er t
his
jum
per
ar
ound
one
lead
of a
10K
2W
res
isto
r to
ex
tend
the
lead
of t
he re
sist
or .
Ad
d t
his
10
K 2
W r
esi
sto
r w
ith
th
e ex
tens
ion
bet
wee
n tu
rret
s 11
and
46 .
Ad
d a
2-3/
4" y
ello
w ju
mp
er to
turr
et 4
6 .
S
TE
P 7
4
Ad
d fo
ur
resi
sto
rsA
dd
a 47
0Ω r
esis
tor
bet
wee
n tu
rret
s 31
an
d 44
.
Ad
d a
1M
res
isto
r b
etw
een
tu
rret
s 31
an
d 45
.
Ad
d an
othe
r 1M
resi
stor
bet
wee
n tu
rret
s 31
and
43 .
Ad
d a
10K
res
isto
r b
etw
een
tu
rret
s 9
and
31 .
S
TE
P 7
5
Inst
all t
wo
cap
acit
ors
+ fo
ur
jum
per
sA
dd
a .
022μ
F ca
p b
etw
een
tu
rret
s 10
an
d 45
.
Ad
d a
.1μF
cap
bet
wee
n tu
rret
s 9
and
43 .
Ad
d a
5" y
ello
w ju
mp
er to
turr
et 1
0 .
Ad
d a
4" y
ello
w ju
mp
er to
turr
et 4
5 .
Ad
d a
2" y
ello
w ju
mp
er to
turr
et 4
4 .
Ad
d a
1-1/
2" y
ello
w ju
mp
er to
turr
et 4
3 .
S
TE
P 7
6
Ad
d fo
ur
resi
sto
rsA
dd
a 10
0K r
esis
tor
bet
wee
n tu
rret
s 30
an
d 42
.
Ad
d an
82K
res
isto
r b
etw
een
turr
ets
30
and
41 .
Ad
d a
220
K re
sist
or b
etw
een
turr
ets
8 an
d 24
.
Ad
d a
no
ther
220
K r
esis
tor
bet
wee
n tu
rret
s 7
and
24 .
S
TE
P 7
7
Ad
d t
hre
e ca
pac
ito
rs a
nd
tw
o
jum
per
sA
dd
a 47
pF
cap
bet
wee
n tu
rret
s 41
and
42
.
Ad
d a
.1μF
cap
bet
wee
n tu
rret
s 8
and
42 .
Ad
d a
not
her
.1μ
F ca
p b
etw
een
turr
ets
7 an
d 41
.
Ad
d a
2" y
ello
w ju
mp
er to
turr
et 4
2 .
Ad
d a
3-3/
4" y
ello
w ju
mp
er to
turr
et 4
1 .
S
TE
P 7
8
Ad
d o
ne
res
isto
r +
tw
o ju
mp
ers
Cut t
wo
1" y
ello
w ju
mp
er a
nd re
mov
e th
e in
sula
tion .
Wra
p a
nd s
old
er o
ne ju
mp
er
aro
un
d o
ne
lead
of
a 27
K r
esis
tor
to
exte
nd th
e le
ad o
f the
resi
stor
.
Ad
d t
his
27K
res
isto
r w
ith
ext
ensi
on
bet
wee
n tu
rret
s 6
and
40 .
Ad
d a
7" y
ello
w ju
mp
er to
turr
et 6
.
Ad
d a
4" y
ello
w ju
mp
er to
turr
et 4
0 .
S
TE
P 7
9
Ad
d t
wo
res
isto
rs +
on
e ju
mp
erA
dd
a 1
0K 2
W r
esis
tor
bet
wee
n tu
rret
s 5
and
29 .
Ad
d a
1K 5
W re
sist
or b
etw
een
turr
ets
29
and
39 .
Ad
d a
2-1/
2" y
ello
w ju
mp
er to
turr
et 3
9 .
S
TE
P 8
0
Ad
d t
hre
e ju
mp
ers
Cut
a 3-
1/2"
gre
en ju
mp
er a
nd r
emov
e th
e in
sula
tion .
Sta
rtin
g at
tur
ret
2, w
rap
in
a f
igu
re 8
pat
tern
aro
un
d t
urr
et 3
, co
mp
lete
ly a
roun
d tu
rret
4, a
nd t
hen
in
an o
ppos
ite fi
gure
8 p
atte
rn a
roun
d tu
rret
3,
and
bac
k to
turr
et 2
. Thi
s cr
eate
s a
bus
co
nnec
ting
turr
ets
2, 3
, and
4 .
Cu
t tw
o 1
" g
reen
ju
mp
er a
nd
rem
ove
thei
r ins
ulat
ion .
Wra
p o
ne a
roun
d tu
rret
s 37
an
d 3
8 an
d w
rap
th
e ot
her
aro
und
turr
ets
35 a
nd 3
6 .
stew
mac
.co
m
32
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2019
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wM
ac
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37
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26
3033
27 35
2931
3225
34
36
34
56
78
910
1112
1314
1516
1718
1920
2122
+ 8µF
+ 8µF
stew
mac
.co
m
33
©
2019
St
ewM
ac
S
TE
P 8
1
Ad
d o
ne
resi
sto
r +
tw
o c
apac
ito
rsA
dd
a 6
8K r
esis
tor
bet
wee
n t
urr
ets
4 an
d 28
.
Ad
d a
n 8
μF
ele
ctro
lyti
c ca
pac
ito
r b
etw
een
tu
rret
s 3
and
37 .
Th
is c
ap i
s p
olar
ized
, so
be
sure
the
neg
ativ
e le
ad
goes
to
turr
et 3
7 an
d th
e p
ositi
ve le
ad
to tu
rret
3 .
Ad
d a
noth
er 8
μF
elec
trol
ytic
cap
acito
r b
etw
een
turr
ets 2
and
36 .
Thi
s cap
is a
lso
pol
ariz
ed, s
o b
e su
re t
he n
egat
ive
lead
go
es t
o tu
rret
36
and
the
pos
itive
lead
to
turr
et 2
.
S
TE
P 8
2
Ad
d o
ne
jum
per
Ad
d a
3" g
reen
jum
per
to tu
rret
2 . R
oute
th
is ju
mp
er to
the
left
of t
he tu
rret
boa
rd .
S
TE
P 8
3
Ad
d t
wo
res
isto
rs a
nd
a d
iod
eA
dd
a 2
20K
resi
stor
bet
wee
n tu
rret
s 1
and
27 .
Ad
d a
15K
res
isto
r b
etw
een
tur
rets
36
and
37 .
Ad
d th
e 1N
4007
dio
de
bet
wee
n tu
rret
s 27
and
35 .
No
te t
he
po
lari
ty o
f th
e d
iod
e . T
he
pos
itiv
e le
ad o
f th
e d
iod
e is
in
dic
ated
by
a s
trip
e at
tha
t en
d . T
he e
nd w
ith n
o st
ripe
is n
egat
ive .
Con
nect
the
nega
tive
lead
to
turr
et 3
5 . C
onne
ct t
he p
osit
ive
lead
to tu
rret
27 .
Sto
p a
nd
insp
ect
you
r w
ork
All
the
com
pon
ents
and
wire
s are
now
on
the
turr
et b
oard
. Tak
e a
bre
ak to
rest
you
r ey
es b
efor
e m
akin
g su
re y
ou’v
e fo
llow
ed
each
ste
p c
orre
ctly
.
To fi
nd n
o m
ista
kes
at t
his
stag
e w
ould
b
e su
rpris
ing,
and
it’s
muc
h le
ss w
ork
to
find
them
now
tha
n af
ter
sold
erin
g! A
s yo
u ch
eck
your
wor
k, m
ake
sure
all
the
conn
ectio
ns a
re ti
ght .
S
TE
P 8
4
Sold
er t
he
com
po
nen
ts o
n t
he
turr
et b
oar
dIt
’s t
ime
to s
et a
ll th
e co
nnec
tions
with
so
lder
.
Revi
ew t
he
tip
s fo
r g
reat
sol
der
ing
on
pag
e 9,
the
n so
lder
eac
h co
nnec
tion
on
the
turr
et b
oard
.
Aft
er a
ll th
e jo
ints
are
sol
der
ed c
lip t
he
exce
ss le
ads
from
the
tur
rets
. Trim
min
g th
e ex
cess
lead
s is
imp
orta
nt t
o av
oid
a sh
ort i
n yo
ur c
ircui
t . C
heck
all
your
sold
er
join
ts t
o m
ake
sure
the
y’re
shi
ny, a
nd t
o se
e th
at y
ou d
idn’
t mis
s on
e .
STOP
Be fus
sy Fin
d the
mistak
e now
, not
later!
Sold
er c
om
po
nen
ts t
o t
urr
et b
oar
d
stew
mac
.co
m
34
©
2019
Ste
wM
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2
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4140
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37
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26
3033
27 35
2931
3225
34
36
34
56
78
910
1112
1314
1516
1718
1920
2122
Beh
ind
bo
ard
vie
w
stew
mac
.co
m
35
©
2019
St
ewM
ac
S
TE
P 8
5
Ad
d t
en b
ehin
d-t
he-
bo
ard
jum
per
sTh
e w
iring
dia
gram
ab
ove
is n
ow a
vie
w
of t
he t
urre
t b
oard
flip
ped
ove
r . O
rient
yo
ur b
oard
as
show
n in
the
dia
gram
to
sim
plif
y in
stal
lati
on
of
the
beh
ind
th
e b
oard
jum
per
s .
Cu
t th
ese
jum
per
s to
len
gth
an
d t
rim
3/
8" o
f sh
ield
ing
off e
ach
end
. Run
the
ex
pos
ed e
nds
up in
to th
e b
otto
m o
f the
tu
rret
s an
d so
lder
them
into
pla
ce .
Cut
a 4"
yel
low
jum
per
and
sol
der
one
en
d t
o th
e b
otto
m o
f tu
rret
26 .
Rou
te
the
free
end
str
aigh
t d
own
tow
ard
the
b
otto
m o
f th
e b
oar
d, b
etw
een
tur
rets
50
and
51 .
Cut a
noth
er 4
" yel
low
jum
per
and
sol
der
on
e en
d to
the
bot
tom
of t
urre
t 33 .
Pla
ce
the
othe
r end
in th
e b
otto
m o
f tur
ret 4
6 b
ut d
on't
sold
er it
yet
.
Cut
a 12
" ye
llow
jum
per
and
sol
der
one
en
d to
the
bot
tom
of t
urre
t 46
with
the
ju
mp
er a
lread
y in
pla
ce . R
oute
the
fre
e en
d of
this
jum
per
tow
ard
turr
et 2
7 .
Cut
a 3"
yel
low
jum
per
and
sol
der
it t
o th
e b
ack
of
turr
et 3
0 . P
lace
th
e o
ther
en
d in
to th
e b
otto
m o
f tur
ret 5
but
don
’t so
lder
it y
et .
Cut a
n 8-
1/2"
yel
low
jum
per
and
ad
d on
e en
d to
the
bot
tom
of
turr
et 5
but
don
't so
lder
this
yet
eith
er . R
oute
the
free
end
of
this
jum
per
tow
ard
turr
et 2
7 .
Cut
a 4"
yel
low
jum
per
and
sol
der
one
en
d t
o th
e b
otto
m o
f tu
rret
5 w
ith t
he
oth
er t
wo
ju
mp
ers
alre
ady
in p
lace
. So
lder
the
othe
r end
of t
his
4" ju
mp
er to
th
e b
otto
m o
f tur
ret 1
1 .
Sold
er o
ne e
nd o
f a 2
-1/4
" yel
low
jum
per
to
the
bot
tom
of t
urre
t 6
and
sold
er t
he
othe
r end
to th
e b
otto
m o
f tur
ret 9
.
Cut
an 8
" ye
llow
jum
per
and
sol
der
one
en
d to
the
bot
tom
of t
urre
t 29 .
Rou
te th
e fr
ee e
nd to
war
d tu
rret
27 .
Cut a
4-1
/2" y
ello
w ju
mp
er a
nd so
lder
one
en
d to
the
bot
tom
of t
urre
t 28 .
Rou
te th
e fr
ee e
nd to
war
d tu
rret
27 .
Cut a
5-3
/4" y
ello
w ju
mp
er a
nd so
lder
one
en
d to
the
bot
tom
of t
urre
t 24 .
Rou
te th
e fr
ee e
nd to
war
d tu
rret
27 .
Cut
a 4"
yel
low
jum
per
and
sol
der
one
en
d to
the
bot
tom
of t
urre
t 38 .
Rou
te th
e fr
ee e
nd to
war
d tu
rret
27 .
S
TE
P 8
6
Ad
d t
wo
mo
re b
ehin
d-t
he-
bo
ard
ju
mp
ers
Cut
a 5"
yel
low
jum
per
and
a 6
" ye
llow
ju
mp
er . S
trip
1"
of in
sula
tion
fro
m o
ne
end
of e
ach .
Ad
d a
5 .1K
resi
stor
to th
e st
ripp
ed e
nd o
f ea
ch o
f th
ese
jum
per
s . O
nce
the
sold
er
join
ts c
oo
l, ad
d 1
" o
f 1/
8" h
eat-
shri
nk
tub
ing
to in
sula
te th
e so
lder
join
t .
On
ce t
he
hea
t sh
rink
co
ols,
sol
der
th
e re
sist
or fr
ee e
nd o
f the
5"
jum
per
to
the
bot
tom
of t
urre
t 8 . R
oute
the
end
of th
is
jum
per
with
the
resi
stor
att
ache
d to
war
d tu
rret
37 .
Sold
er t
he
resi
sto
r fr
ee e
nd
of
the
6"
jum
per
to
the
bot
tom
of t
urre
t 7 .
Rou
te
the
end
of t
his
jum
per
with
the
res
isto
r at
tach
ed to
war
d tu
rret
27 .
S
TE
P 8
7
Ch
eck
the
con
tin
uit
y o
f yo
ur
bac
k-o
f-b
oar
d ju
mp
ers
On
ce a
ll o
f th
ese
sold
er
join
ts a
re
set,
flip
th
e b
oar
d b
ack
over
an
d t
est
for
con
tin
uit
y o
n e
ach
pai
r o
f tu
rret
s co
nnec
ted
by
bac
k-of
-boa
rd r
uns .
Use
a
mul
tim
eter
for
con
tinu
ity
test
ing
, as
des
crib
ed o
n p
age
43 .
You
sh
ou
ld h
ave
con
tin
uit
y o
n t
he
follo
win
g p
airs
of t
urre
ts:
n
tur
ret 3
3 to
turr
et 4
6
n
tur
ret 5
to tu
rret
11
n t
urre
t 30
to tu
rret
5
n t
urre
t 6 to
turr
et 9
S
TE
P 8
8
Org
aniz
e th
e b
ehin
d-t
he-
bo
ard
ju
mp
ers
Twis
ting
som
e of
thes
e ju
mp
ers t
oget
her
wil
l h
elp
org
aniz
e t
he
m f
or
eas
ier
asse
mb
ly la
ter,
and
it w
ill h
elp
kee
p th
em
tid
y in
th
e lo
ng
run
. Rem
emb
er, g
oo
d le
ad d
ress
mea
ns le
ss n
oise
. (se
e p
age
37)
Thre
e of
the
se ju
mp
ers
will
be
goin
g to
th
e fil
ter c
apac
itors
mou
nted
aga
inst
the
sid
e w
all .
Thes
e ju
mp
ers
will
be
carr
ying
hi
gh v
olta
ge t
o th
e tu
rret
boa
rd, s
o w
e w
ant t
o tw
ist t
hem
toge
ther
to k
eep
them
ne
at a
nd a
way
from
sign
al c
arry
ing
wire
s .
Twis
t the
jum
per
s co
min
g fr
om tu
rret
s 5,
29
, and
46
toge
ther
. Kee
p t
hem
rou
ted
pas
t tur
ret 2
7 on
ce th
ey a
re t
wis
ted
.
Twis
ting
the
jum
per
s to
the
bia
s p
ot is
al
so a
goo
d id
ea . T
hese
jum
per
s co
me
from
tur
rets
24,
28,
and
38 .
Tw
ist
them
to
get
her
an
d r
ou
te t
he
twis
ted
lea
ds
pas
t tur
ret 2
7 .
Mak
e su
re t
he ju
mp
er f
rom
the
bac
k of
tu
rret
8 is
rout
ed p
ast t
urre
t 37,
and
mak
e su
re t
he ju
mp
er f
rom
tur
ret
7 is
rou
ted
pas
t tur
ret 2
7 .
S
TE
P 8
9
Glu
e b
ehin
d-t
he-
bo
ard
jum
per
s d
ow
nA
s yo
ur
amp
ag
es,
it w
ill n
eed
par
ts
rep
lace
d .
Wh
en y
ou
hea
t a
turr
et t
o re
mov
e a
wor
n-o
ut p
art,
a b
ehin
d-t
he-
bo
ard
ju
mp
er c
ou
ld c
om
e d
islo
dg
ed
from
the
bac
k of
the
tur
ret,
intr
oduc
ing
a w
hole
new
pro
ble
m . T
o p
reve
nt t
his,
ap
ply
a d
ime
size
d a
mou
nt o
f co
ntac
t ce
men
t to
eac
h w
ire'
s in
sula
tio
n a
s sh
own .
Thi
s w
ill h
old
the
jum
per
s tig
ht
to th
e b
ack
of th
e b
oard
eve
n w
hen
you
heat
the
turr
et a
nd s
old
er li
quefi
es .
Allo
w t
his
glue
to c
ure
over
nigh
t . Th
is is
a
good
cha
nce
to s
top
and
dou
ble
che
ck
all
of y
our
conn
ecti
ons
one
mor
e ti
me
bef
ore
inst
allin
g t
he t
urre
t b
oard
in t
o th
e ch
assi
s .
stew
mac
.co
m
36
©
2019
Ste
wM
ac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
IND
ICAT
OR
LIG
HT
PRES
ENCE
BASS
MID
DLE
TREB
LEH
IGH
TRE
BLE
LOU
DN
ESS
1N
ORM
AL
LOU
DN
ESS
2IN
PUT
1(H
IGH
TRE
BLE)
INPU
T 2
(NO
RMA
L)
POW
ER IN
LET
FUSE
H.T
. FU
SEIM
PED
AN
CE
V6 5AR4
V3
12A
X7V
212
AX7
V112
AX7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
12
43
12
43
AA BB
12
43
12
43
AA BB
1MA
1MA
25KL
250KL
5KL
4 3
21
87
65
4 3
21
87
65
4 3
21
87
65
6
4 321
98
75
6
4 321
98
75
6
4 321
98
75
2
123 52
5150
4948
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3938
37
2824
26
3033
27 35
2931
3225
34
36
34
56
78
910
1112
1314
1516
1718
1920
2122
250
stew
mac
.co
m
37
©
2019
St
ewM
ac
You
're
read
y to
inst
all t
he
turr
et
bo
ard
in t
he
chas
sis.
It’s
tim
e to
rem
ove
yo
ur
tap
e w
ith
the
turr
et n
umb
ers .
Wh
en t
he
bo
ard
’s
inst
alle
d, y
ou w
on’t
be
able
to g
et a
t the
ta
pe
to r
emov
e it
. Fro
m t
his
poi
nt o
n,
you
can
iden
tify
jum
per
s an
d tu
rret
s by
re
ferr
ing
to th
e di
agra
ms .
S
TE
P 9
0
Ad
d t
he
last
filt
er c
ho
ke le
adBe
fore
mou
ntin
g th
e tu
rret
boa
rd in
the
chas
sis,
sol
der
the
last
filte
r ch
oke
lead
to
the
bot
tom
of t
urre
t 29
alon
g w
ith th
e ju
mp
er a
lread
y in
pla
ce .
S
TE
P 9
1
Inst
all t
he
turr
et b
oar
dTo
kee
p t
he
turr
et b
oar
d c
on
nec
tio
ns
from
sho
rtin
g ag
ains
t th
e m
etal
cha
ssis
, th
e b
oard
is m
ount
ed o
n fo
ur t
hrea
ded
st
and
off
s th
at h
old
it
away
fro
m t
he
chas
sis
Use
4-4
0 sc
rew
s to
mo
un
t th
ese
fou
r st
ando
ffs t
o th
e ch
assi
s . L
ine
up th
e tu
rret
b
oard
on
thes
e st
and
offs .
S
TE
P 9
2
Sold
er t
he
no
rmal
ch
ann
el ja
cks
Sold
er th
e ju
mp
er fr
om tu
rret
21
to lu
g 4
of n
orm
al c
hann
el ja
ck B
.
Sold
er th
e ju
mp
er fr
om tu
rret
22
to lu
g 4
of n
orm
al c
hann
el ja
ck A
.
Sold
er th
e ju
mp
er fr
om tu
rret
23
to lu
g 2
of n
orm
al c
hann
el ja
ck A
.
S
TE
P 9
3
Sold
er t
he
hig
h t
reb
le c
han
nel
jack
sSo
lder
the
jum
per
from
turr
et 1
9 to
lug
4 of
hig
h tr
eble
cha
nnel
jack
B .
Sold
er th
e ju
mp
er fr
om tu
rret
18
to lu
g 4
of h
igh
treb
le c
hann
el ja
ck A
.
S
TE
P 9
4
Sold
er t
he
no
rmal
ch
ann
el lo
ud
nes
s p
ot
Sold
er t
he ju
mp
er f
rom
tur
ret
20 t
o th
e rig
ht lu
g of
the
norm
al c
hann
el lo
udne
ss
pot
.
Sold
er t
he
jum
per
fro
m t
urr
et 1
6 to
th
e m
idd
le l
ug
of
the
no
rmal
ch
ann
el
loud
ness
pot
.
Sold
er t
he ju
mp
er f
rom
tur
ret
14 t
o th
e b
ack
of th
e no
rmal
cha
nnel
loud
ness
pot
.
S
TE
P 9
5
Sold
er t
he
hig
h t
reb
le c
han
nel
lo
ud
nes
s p
ot
Ad
d a
250
pF
cap
acit
or
bet
wee
n t
he
right
and
mid
dle
lugs
of t
he h
igh
treb
le
chan
nel
loud
ness
pot
but
don
't so
lder
th
e le
ads
yet .
Sold
er t
he
jum
per
fro
m t
urr
et 1
7 to
th
e rig
ht lu
g of
the
hig
h tr
eble
cha
nnel
lo
udn
ess
pot
alo
ng
wit
h th
e ca
pac
itor
le
ad a
lread
y in
pla
ce .
Sold
er t
he ju
mp
er f
rom
tur
ret
15 t
o th
e m
idd
le l
ug
of
the
hig
h t
reb
le c
han
nel
lo
udn
ess
pot
alo
ng
wit
h th
e ca
pac
itor
le
ad a
lread
y in
pla
ce .
S
TE
P 9
6
Sold
er t
he
treb
le p
ot
Sold
er t
he ju
mp
er f
rom
tur
ret
32 t
o th
e rig
ht lu
g of
the
treb
le p
ot .
Sold
er t
he ju
mp
er f
rom
tur
ret
10 t
o th
e m
iddl
e lu
g of
the
treb
le p
ot .
Sold
er th
e ju
mp
ers
from
turr
et 1
3 to
the
left
lug
of th
e tr
eble
pot
.
S
TE
P 9
7
Sold
er t
he
mid
s p
ot
Sold
er t
he ju
mp
er f
rom
tur
ret
12 t
o th
e m
iddl
e lu
g of
the
mid
s p
ot .
S
TE
P 9
8
Sold
er t
he
pre
sen
ce p
ot
Sold
er t
he j
ump
er f
rom
tur
ret
6 to
the
rig
ht lu
g of
the
pre
senc
e p
ot .
S
TE
P 9
9
Sold
er t
he
gro
un
d ju
mp
erSo
lder
the
gre
en j
ump
er f
rom
tur
ret
2 to
the
3-lu
g gr
ound
ing
stri
p u
nder
the
p
rese
nce
pot
.
Four
sta
ndo
s
Inst
alli
ng
th
e tu
rret
bo
ard
in t
he
chas
sis
Tip
s fo
r le
ad d
ress
wit
h ju
mp
ers
As
gen
eral
ru
le f
or
inst
alli
ng
th
ese
jum
per
s, w
hen
two
jum
per
s cr
oss
over
ea
ch o
ther
, ben
d th
em s
o th
ey c
ross
at
90°
angl
es r
athe
r ru
nnin
g si
de-
by-
sid
e .
This
lead
dre
ss d
etai
l infl
uenc
es th
e am
p’s
soun
d, e
spec
ially
on
a hi
gh-g
ain
circ
uit
like
this
one
.
stew
mac
.co
m
38
©
2019
Ste
wM
ac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
IND
ICAT
OR
LIG
HT
PRES
ENCE
BASS
MID
DLE
TREB
LEH
IGH
TRE
BLE
LOU
DN
ESS
1N
ORM
AL
LOU
DN
ESS
2IN
PUT
1(H
IGH
TRE
BLE)
INPU
T 2
(NO
RMA
L)
POW
ER IN
LET
FUSE
H.T
. FU
SEIM
PED
AN
CE
V6 5AR4
V3
12A
X7V
212
AX7
V112
AX7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
-
4 3
21
87
65
4 3
21
87
65
4 3
21
87
65
6
4 321
98
75
6
4 321
98
75
6
4 321
98
75
-
D C
-
B A
-
1
23
4
12
43
12
43
12
43
12
43
2
123 52
5150
4948
4746
4544
4342
4140
3938
37
2824
26
3033
27 35
2931
3225
34
36
34
56
78
910
1112
1314
1516
1718
1920
2122
stew
mac
.co
m
39
©
2019
St
ewM
ac
S
TE
P 1
00
Sold
er t
he
jum
per
s to
V1
Sold
er t
he ju
mp
er f
rom
tur
ret
51 t
o V1
p
in 1
.
Sold
er t
he ju
mp
er f
rom
tur
ret
50 t
o V1
p
in 6
.
Sold
er t
he
beh
ind
-th
e-b
oar
d j
um
per
fr
om tu
rret
26
to V
1 p
in 7
.
Sold
er t
he ju
mp
er f
rom
tur
ret
34 t
o V1
p
in 2
.
Sold
er th
e ju
mp
er fr
om tu
rret
52
to V
1 pi
n 8
alon
g w
ith th
e ju
mp
er a
lread
y in
pla
ce .
S
TE
P 1
01
Sold
er t
he
jum
per
s to
V2
Sold
er t
he ju
mp
er f
rom
tur
ret
46 t
o V2
p
in 6
alo
ng w
ith th
e re
sist
or le
ad a
lread
y in
pla
ce .
Sold
er t
he ju
mp
er f
rom
tur
ret
48 t
o V2
p
in 8
.
Sold
er t
he ju
mp
er f
rom
tur
ret
49 t
o V2
p
in 3
.
Sold
er t
he ju
mp
er f
rom
tur
ret
25 t
o V2
p
in 2
.
S
TE
P 1
02
Sold
er t
he
jum
per
s to
V3
Sold
er t
he ju
mp
er f
rom
tur
ret
41 t
o V3
p
in 1
.
Sold
er t
he ju
mp
er f
rom
tur
ret
42 t
o V3
p
in 6
.
Sold
er t
he ju
mp
er f
rom
tur
ret
43 t
o V3
p
in 7
.
Sold
er t
he ju
mp
er f
rom
tur
ret
45 t
o V3
p
in 2
.
Sold
er th
e ju
mp
er fr
om tu
rret
44
to V
3 pi
n 8
alon
g w
ith th
e ju
mp
er a
lread
y in
pla
ce .
S
TE
P 1
03
Sold
er t
he
jum
per
s to
V4
Sold
er t
he ju
mp
er f
rom
tur
ret
39 t
o V4
p
in 6
alo
ng w
ith th
e ju
mp
er a
nd re
sist
or
lead
alre
ady
in p
lace
.
Sold
er th
e ju
mp
er fr
om tu
rret
8 (r
unni
ng
unde
rnea
th th
e b
oard
with
a 5
.1k
resi
stor
at
tach
ed to
the
end)
to V
4 pi
n 5 .
You
wan
t to
sol
der
thi
s re
sist
or v
ery
clos
e to
the
tu
be
sock
et, a
s p
ictu
red
in th
e di
agra
m .
S
TE
P 1
04
Sold
er t
he
jum
per
s to
V5
Sold
er th
e ju
mp
er fr
om tu
rret
7 (r
unni
ng
unde
rnea
th th
e b
oard
with
a 5
.1k
resi
stor
at
tach
ed to
the
end)
to V
5 pi
n 5 .
You
wan
t to
sol
der
thi
s re
sist
or v
ery
clos
e to
the
tu
be
sock
et, a
s p
ictu
red
in th
e di
agra
m .
S
TE
P 1
05
Sold
er t
he
jum
per
s to
V6
Sold
er t
he ju
mp
er f
rom
pin
6 o
f so
cket
V6
to tu
rret
1 .
S
TE
P 1
06
Sold
er o
ne
jum
per
Sold
er th
e ju
mp
er fr
om tu
rret
40
to lu
g 1
of t
he im
ped
ance
sel
ecto
r sw
itch
alon
g w
ith th
e or
ange
out
put
tran
sfor
mer
lead
.
S
TE
P 1
07
Sold
er t
he
jum
per
s to
th
e b
ias
po
tTh
e sh
orte
r set
of t
hree
twis
ted
jum
per
s co
min
g fr
om t
he l
eft
sid
e of
the
tur
ret
boa
rd a
re g
oing
to
the
bia
s p
ot . T
hese
th
ree
jum
per
s w
ill h
ave
con
tin
uit
y to
tu
rret
s 24
, 28,
and
38 .
Find
the
jum
per
with
con
tinui
ty to
turr
et
28 a
nd s
old
er it
to th
e le
ft lu
g of
the
bia
s p
ot .
Find
the
jum
per
with
con
tinui
ty to
turr
et
24 a
nd s
old
er it
to th
e m
iddl
e lu
g of
the
bia
s p
ot .
Find
the
jum
per
with
con
tinui
ty to
turr
et
38 a
nd s
old
er it
to
the
righ
t lu
g of
the
b
ias
pot
.
S
TE
P 1
08
Sold
er t
he
jum
per
s to
th
e fi
lter
cap
sTh
e ot
her
set
of t
hree
tw
iste
d ju
mp
ers
com
ing
from
the
lef
t si
de
of t
he t
urre
t b
oard
are
goi
ng to
the
filte
r cap
s . T
hese
th
ree
jum
per
s w
ill h
ave
con
tin
uit
y to
tu
rret
s 5,
29,
and
46 .
Find
the
jum
per
with
con
tinui
ty to
turr
et
5 an
d so
lder
it to
filte
r cap
lug
A .
Find
the
jum
per
with
con
tinui
ty to
turr
et
46 a
nd s
old
er it
to fi
lter c
ap lu
g B .
Find
the
jum
per
with
con
tinui
ty to
turr
et
29 a
nd s
old
er it
to fi
lter c
ap lu
g C
.
stew
mac
.co
m
40
©
2019
Ste
wM
ac
V5 EL34
V4 EL34
POW
ERST
AN
DBY
IND
ICAT
OR
LIG
HT
PRES
ENCE
BASS
MID
DLE
TREB
LEH
IGH
TRE
BLE
LOU
DN
ESS
1N
ORM
AL
LOU
DN
ESS
2IN
PUT
1(H
IGH
TRE
BLE)
INPU
T 2
(NO
RMA
L)
POW
ER IN
LET
FUSE
H.T
. FU
SEIM
PED
AN
CE
V6 5AR4
V3
12A
X7V
212
AX7
V112
AX7
SPEA
KER
EXTE
NSI
ON
SPEA
KER
-
4 3
21
87
65
1 2
1 2
3 41
23
4
12
43
12
43
12
43
12
43
4 3
21
87
65
4 3
21
87
65
6
4 321
98
75
6
4 321
98
75
6
4 321
98
75
2
123 52
5150
4948
4746
4544
4342
4140
3938
37
2824
26
3033
27 35
2931
3225
34
36
34
56
78
910
1112
1314
1516
1718
1920
2122
stew
mac
.co
m
41
©
2019
St
ewM
ac
S
TE
P 1
09
Inst
all t
he
spea
ker
jack
sIn
stal
l th
e la
st c
om
po
nen
t in
to
th
e ch
assi
s, th
e ex
tens
ion
spea
ker j
ack .
The
two
-lug
jack
is th
e ex
tens
ion
spea
ker
jack
and
goe
s to
the
rig
ht o
f th
e m
ain
spea
ker j
ack .
S
TE
P 1
10
Wir
e u
p t
he
spea
ker
jack
sC
ut
a 2"
yel
low
ju
mp
er a
nd
wra
p i
t th
roug
h lu
g 1
of t
he t
wo
-lug
exte
nsio
n sp
eake
r ja
ck a
nd
th
e ot
her
en
d o
f th
e ju
mp
er in
to lu
g 3
of th
e fo
ur-lu
g sp
eake
r ja
ck . S
old
er t
his
jum
per
to
lug
1 of
the
tw
o-lu
g ja
ck .
Cut a
1-1
/2" g
reen
jum
per
and
sold
er it
to
lug
2 of
the
tw
o-lu
g ex
tens
ion
spea
ker
jack
and
wra
p t
he o
ther
end
to
pin
1 o
f th
e fo
ur-lu
g sp
eake
r jac
k .
Cut
a 1
" g
reen
jum
per
an
d s
old
er o
ne
end
to lu
g 1
of th
e fo
ur-lu
g sp
eake
r jac
k al
ong
with
the
jum
per
alre
ady
in p
lace
. W
rap
the
oth
er e
nd t
o lu
g 4
of t
he fo
ur-
lug
spea
ker j
ack
but
don
't so
lder
it y
et .
Cut a
3" g
reen
jum
per
and
sold
er o
ne e
nd
to lu
g 4
of th
e fo
ur-lu
g sp
eake
r jac
k al
ong
with
the
jum
per
alre
ady
in p
lace
. Sol
der
th
e ot
her
end
of t
his
jum
per
to
pin
8 o
f so
cket
V4 .
Cut a
4-1
/4" y
ello
w ju
mp
er a
nd so
lder
one
en
d in
to lu
g 3
of th
e fo
ur-lu
g sp
eake
r jac
k al
ong
with
the
jum
per
alre
ady
in p
lace
. So
lder
the
oth
er e
nd o
f th
is j
ump
er t
o lu
g 4
on th
e im
ped
ance
sel
ecto
r sw
itch .
Take
a b
reak
an
d r
evie
w y
ou
r w
ork
Now
you
’ve
sold
ered
th
e co
mp
onen
ts
and
wire
s, a
nd it
's t
ime
to t
ake
a b
reak
. Re
st y
our e
yes a
nd re
view
you
r wor
k la
ter,
care
fully
sea
rchi
ng o
ut a
ny e
rror
s b
efor
e yo
u m
ove
on .
STOP
stewmac.com 42 © 2019 StewMac
STEP 111
Glue the tube placement chartCut out the chart on page 53 . With a thin coat of glue or contact cement, glue it to the inside wall of the cabinet .
STEP 112
Install the fusesInstall the 3-amp fuse in the mains fuse socket and the 500mA fuse in the H .T . fuse socket .
Installing parts and preparing for testing
STOP!
DON’T INSTALL THE TUBES YET! DON’T PLUG THE AMP IN YET!
The next page is going to keep you out of trouble!
STEP 114
Set the chassis on chassis stand or on blocks for testingSet your chassis up for final testing . Chassis stands are extremely useful for this . If you do not have a chassis stand a couple of blocks of wood can work just fine .
STEP 113
Install the seven control knobsTurn the shaft of each pot all the way counterclockwise to the “off” point and install the knob so the indicator line points to zero . Don't forget the knob for the impedance selector switch on the back .
stewmac.com 43 © 2019 StewMac
At this point, dangerous voltage is forming in the filter caps. Always discharge them before working on the circuit, even if the amp is unplugged. See how to use a snuffer stick on page 6 .
For safety, use only one hand to probe the amp during DC tests.
Keep your other hand behind your back when you need to probe a component . This way, you can’t be a path between B+ voltage and ground—a mistake that would send a dangerous charge through your heart .
Set your multimeter to 600V DC and connect the negative lead to ground . Once the negative lead is secured to ground, flip the standby switch to ON . Measure the DC voltage at lug A of the first filter cap . It should be roughly 500V DC .
Turn the power and standby switches to OFF and unplug the amp .
Any multimeter will work fine for the two types of tests we’re about to do: checking continuity and reading voltages . The instructions that came with your meter will be helpful .
Continuity testing is simply making sure current flows between two points successfully . Touch the meter's red lead to one end of the section being tested, and the black lead to the other end . If the continuity is good, your meter will beep or register this on the display .
Voltage testing is where you need to be careful . Some steps require the amp to be plugged in and turned on . This becomes dangerous if you’re not cautious . Respect the voltages and follow the directions, and these tests are safe and easy .
STEP 115
Perform a safe power-upAt this point, there should be no tubes installed, and the speaker should be disconnected .
Before plugging the amp in, turn the power switch to ON . Switching the amp on before the first power-up protects you from shock if a mistake in your wiring has created a short to the chassis . If this short exists, an indication would be that the pilot light will not turn on, since the AC current is going directly to ground .
Plug the power cord in . The pilot lamp should light .
For a few minutes, check for smoke or unusual smells . If anything seems unusual, disconnect the power immediately and carefully review all your connections .
STEP 116
Test the standard AC voltageSet your multimeter to 20V AC . Check the heater voltage across pin 9 and pins 4+5 on the V1 12AX7 socket . This should read between 5-7V AC . If this reading is drastically different, disconnect power and check your connections .
If the amp seems normal, unplug the power cord while still leaving the power switch ON .
Testing and troubleshooting
6
43 2 1
9875
V1
B
A
-
ALWAYS discharge the filter cap
before working on the circuit. See how
to use a snuffer stick on page 6.
And seriously, keep one hand behind
your back!
STEP 117
Test the dangerous DC voltageThe dangerously high DC voltage that passes through the rectifier tube and the filter caps is referred to as “B+” . The next step is to test this B+ voltage .
With the amp still unplugged, install the 5AR4 rectifier tube while spreading the tension clip with the other hand . Take care to position the indexing key correctly in the socket .
Plug the power cord back in . The pilot lamp should light, along with the filament inside the 5AR4 rectifier tube .
Again, spend a few moments checking for smoke or smells .
stewmac.com 44 © 2019 StewMac
STEP 118
Test the preamp tubesUnplug the amp use the snuffer stick to discharge the capacitors, then install the three preamp tubes .
After these tubes are installed, plug the amp back in and flip the power switch ON . The pilot lamp should light up . Let the amp warm up for a few minutes and then flip the standby switch to ON . Again, if you get smoke or smells, unplug immediately .
Connect your multimeter’s negative lead to ground .
Set the multimeter to 5V DC and check turret 52, which should read around 1 .3V .
Set the multimeter to 200V DC and check turret 50 . It should read around 200V .
Set the multimeter to 100V DC and test pin 5 of the V7 and V8 sockets . These readings should be nearly identical .
Use a small flathead screwdriver to turn the center of the bias pot all the way counter-clockwise . This will set the bias for the lowest negative DC voltage . Doing this provides a safe voltage for the power tubes while you set the initial bias .
If all of these voltages come within approximately 10% of their expected values, turn the power switch OFF .
Always turn the power switch off before turning the standby switch off . This will drain the filter capacitors as the amp cools down . After a moment, flip the standby switch OFF as well .
If the reading at turret 50 shows no voltage or low voltage, follow this test: unplug the amp, drain the filter caps with the snuffer stick, set your meter to read continuity, and make sure you have properly installed the back-of-board jumper from turret 46 to turret 33 .
STEP 119
Test the EL34 power tubesWith the amp unplugged, install the EL34 power tubes, turning them so their indexing keys fit correctly in the socket . Turn all of the front panel controls completely counter-clockwise, so the indicator line is pointing to "0" .
Connect the amp to a speaker cabinet, adjust the impedance selector switch for the appropriate impedance, and perform these next tests with the speaker turned away from you . If the amp starts to oscillate and squeal, this will help protect your ears .
Plug the amp in and flip the power switch ON . Give the tubes 30 seconds to warm up and then flip the standby switch to ON as well .
After a few moments you should hear a low hum . If the hum becomes very loud, disconnect the power immediately and review your connections .
Set your multimeter to read 500V DC and test for voltage from pin 3 of both socket V5 and socket V4 . This voltage should read around 450V . Write this number in Box 2 of the calculation in Step 121 . It’ll be needed if you use a bias meter to set your bias .
Set your multimeter to read 50V DC and test for voltage at turret 24 . Adjust the bias pot until this voltage reads around -42V .
If all of these voltages come within approximately 10% of their expected values, turn the power switch OFF . After a few moments turn the standby switch OFF as well, and unplug the amp .
Tube bias affects your sound“Bias” refers to the current of electrons flowing from the cathode to the plate inside your power tubes when the tubes are idle . The bias setting determines this flow and is increased or decreased by the screwdriver-adjustable bias pot .
Adjusting the bias affects your sound: a higher setting gives you punchier cleans and grittier distortion, but your tubes will wear out faster . With a low setting, your tubes last longer but the sound is more sterile . A good bias setting falls between these extremes .
STEP 120
Old method of setting the bias: doing it by earIf you have a bias meter, skip this step and go on to Step 121 .
The old-school way of adjusting the bias is by ear: after setting the bias voltage to a recommended starting point, you make tiny adjustments to the bias pot while listening for the sound you want . This inexact method can shorten the life of your power tubes .
You roughed-in the bias setting in the previous step by setting the bias voltage at -42V .
Danger: set your guitar aside before you adjust the bias pot.
Do not touch any amp circuitry while holding your guitar . Doing so would create an electrocution hazard!
Use a screwdriver to make a tiny adjustment to the bias pot . Turn clockwise to increase the current and counter-clockwise to decrease it . Then set the screwdriver aside and play to hear to the result .
Testing and troubleshooting
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With the amp unplugged allow the power tubes to cool . Once the power tubes have cooled, remove them from their sockets .
Plug the tubes in to the bias probe sockets, which are like tube sockets . Plug the probe sockets with tubes into the power tube sockets .
Plug the amp back in and flip the power switch ON . Give the tubes 30-60 seconds to warm up, then flip the standby switch ON .
Watch the bias meter as the power tubes heat up . Both needles should rise at an equal rate and settle at the same time .
Adjust your bias pot until the bias meter displays the reading you calculated (33mA in our example) . Let the amp idle for a few minutes to make sure that the bias doesn’t drift .
When you see a constant readout of your bias setting, turn the power switch OFF .
After a few moments flip the standby switch OFF and unplug the amp from the wall .
Once the tubes are cool, remove them and the bias probes from the amp and plug the tubes back into the amp's tube sockets without the probes attached .
After removing the bias probes and taking it for a test drive, if the amp is stable and your tests match the voltages specified, feel free to let it rip!
After playing for a few minutes and testing all inputs, if everything seems to be operating normally, go ahead and turn the amp off .
If there are any strange oscillations, squeals, or the amp seems at all unstable, use a wooden chopstick to begin probing for loose connections: n from the input jacks to the turret boardn from the tube sockets to the turret boardn from the tube sockets to the front panel controls .
It usually takes just a minor wiring adjustment, perhaps resoldering a loose joint, to correct this sort of distortion .
Watch out for red-platingYou especially want to avoid too much current turning the gray plates to glowing red . If your tubes start red plating, shut the amp down and let it cool before setting the bias to a lower level .
STEP 121
Improved method of setting the bias: using a bias meterThe more accurate way to set the bias is by using a bias meter, such as the VHT Bias Tester (StewMac #1580) .
This method starts with a simple calculation to find your bias setting, then you adjust the bias pot until your bias meter displays that reading .
The calculation uses two numbers, the tube’s maximum plate dissipation and its plate voltage .
Plate dissipation . Every power tube has a specified plate dissipation—the maximum wattage the tube can handle . For the EL34 power tubes in this amp, that maximum is 25 watts . Exceeding the 25-watt limit will damage the tube, and operating at the full 25 watts will shorten its life . Our goal is to operate the tube at 60% of the 25-watt limit, or 15 watts . We've entered this number for you in Box 1 of the calculation .
Plate voltage . You already have the plate voltage for these tubes: it’s the the number you found in step 119 and wrote in Box 2 below .
Divide Box 1 by Box 2 . The result is your recommended bias setting for use in the next step . Our example calculation gives a bias recommendation of .034 Amps . Since bias is typically measured in milliamps, this measurement is written as 34mA .
Example:
Your plate voltage from Step 16560% of max. plate dissapation
÷Your bias current setting
=15
BOX 2BOX 1
15 ÷ =
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STEP 123
Install the chassisDischarge the capacitors so you can safely handle the chassis . Remove all the cables from their jacks .
Slide the chassis in from the back until its front edge meets the front wall of the cabinet . Insert the mounting screws through the f loor of the chassis . Tighten the locknuts .
Install the preamp tube shields and install the back panel .
Final assembly
Tube lifeThe life span of the power tubes is affected by how hard you drive the amp . If you are overdriving the amp for hours every day, expect the power tubes to have a shorter life span .
We encourage you to experiment with different tube brands and find the brand that is most favorable to your ears and your wallet .
For questions and support, StewMac is here to help!For more than fifty years, StewMac has supplied instrument builders and repair shops . Our customer service team really knows how to help if you run into questions .
Call 800-848-2273 from 9AM–6PM Eastern time, Monday–Friday . Email: service@stewmac .com
Thanks for choosing this StewMac kit, and welcome to the world of amp building!
Tips for using this ampThis amp is known for its rich, articulate clean tones and exceptional sustain: creamy, warm, and a little crispy . If you're looking for AC/DC tones, look no further .
This amp is based on the JTM45 circuit, which is nearly identical to the 5F6A Tweed Bassman circuit . The most notable change is the use of a 12AX7 in V1 instead of a 12AY7 . This gives them amp more gain right out of the gate as the 12AY7 only has a gain factor of 44 compared to the 12AX7's gain factor of 100 .
Despite the wealth of gain in the amp, you will find that it is still very quiet . This is largely due to the large filter caps and the use of the filter choke to smooth out the ripple in the high voltage lines .
The treble, middle, bass tone stack allows you to precisely dial in the exact tone you are looking for . I like to play humbuckers through the high treble channel with a traditional 4x12 Marshall cabinet . With this setup, I prefer to keep the treble around 5, the bass and middle controls around 4, the presence around 4, and the volume around 6 . This positions the amp right on the edge of tube saturation, perfect for kicking on a distortion pedal when you want to take a lead and drive the amp into full-on, tube-saturated glory .
If you are playing through smaller speakers you will probably want to dial the treble and bass back a little bit . If you are using single-coil pickups in your guitar you will most likely want to give yourself a little bump on the bass control and dial your treble back even more .
As with most of these classic amps, it's hard to pull a bad tone from this one . That's why we are still building these circuits half a century later .
Matt Clouston, StewMac
It's finally time to let it rip!
GO!GO!
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OutputGain
Negative feedback
Processing
Power
Mic level
Speaker levelLine level Line level
You don’t need to read a schematic to build this kit . But it’s fun to see how the circuit works, and to see the different subcircuits that interact to shape your sound .
Working with the tiny signal from the guitar, the amp creates the power needed to drive the speaker . The signal is affected by the gain, processing, output and power stages as it passes through the circuit .
The gain circuit increases the signal to line level (about 1 volt), by passing it through a 12AX7 preamp tube where electrons flow from a heated cathode to be received by the anode plate . The grid between these receives the tiny voltage from the guitar, whose varying musical signal controls the flow of electrons to the plate .
This amp’s dirt comes from the first gain stage being biased extremely hot: the small-value 820Ω resistor reduces headroom and increases distortion .
The negative feedback loop flattens and extends the amp’s frequency response, reducing distor tion generated in the output stage . This makes the amp’s sound cleaner and more hi-fi . Some players disable this loop completely or add a potentiometer in place of the resistor to create a “grit control .” We don’t recommend this, because it places stress on the output transformer .
The processing stage shapes the tone . This amp has a universal Treble, Middle, Bass tone control . This allows you to shape each section of the three-band equalizer, and being universal means that the tone controls effect both channels .
The Presence control of this amp uses the negative feedback circuit to introduce more high frequency to the signal, this can be heard as more "bite" to the naked ear . But don't be surprised if the sound engineer at your next gig asks you to turn down the presence, it can be extremely abrasive when mic'd up .
The signal is then sent to the phase inverter which uses all of V3 . The phase inverter then sends the signal to the output section .
The power supply stage provides power to the other circuit stages, as well as the tube heaters .
This circuit receives the AC power from your wall and passes it through the power transformer to create higher voltage . The electricity then goes to the rectifier, which converts it to a pulsing DC current .
This then passes through the filter choke and the filter capacitors . The filter capacitors filter out the pulsing to create a smooth current . As each cap smoothes a bit more, the current is also passing through resistors that lower the voltage .
As the signal from the guitar becomes more amplified, the ripple of DC current becomes less evident and the fully filtered current is sent to the most sensitive part of the amplifier, the first pre-amp tube in the Gain stage .
The output stage increases the line level signal to speaker level, which is typically 8 volts or greater .
Two EL34 tubes drive the output transformer . They receive the split signal, 180 degrees out of phase, amplify those signals, and send them to the output transformer to be recombined into one signal .
T h is t r a ns f o r m e r a djus t s th e impedance to 4, 8, or 16 ohms to drive an external speaker . This amp has an adjustable fixed bias, which means you need to check the bias and possibly make adjustments when you change power tubes .
cathode
plate
grid
We’ve color-coded these stages on our schematic, to show how the parts work together . Symbols for components are in the key at the bottom of the frame .
On the wiring diagram we build step-by-step in these pages, the parts are easier to recognize . But studying these color-coded stages will help you understand where each component fits into the creation of your sound .
Learning more: secrets revealed in the schematic
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stewmac.com 50 © 2019 StewMac
It’s your amp. Your tone. You built it!
’57 MINI TWEED 5W AMP KITOne-knob titan of tone.A timeless studio darling whose tiny size hides tremendous punch and versatility .
The 5F1 circuit was meant to be a student amp but wasn’t kid stuff for long; rock’s finest guitarists hijacked it for some of the greatest songs ever recorded . Listen to Eric Clapton (“Layla") or Joe Walsh (“Rocky Mountain Way") while you build this amp!
Our simplest kit; the quickest way to get into amp building .
#10730 5 WATTS / 8" SPEAKER / ORIGINAL 5F1 CIRCUIT
’65 P-REVERB 15W AMP KITSparkling bright, perfect for the surf.Plug your single-coils straight in for that signature clean American tone, or go surfing with onboard effects .
The smallest member of the black-panel family to offer reverb and tremolo, this amp made its name as a jangly pop dream machine . Aficionados treasure its early low-end breakup powered by a pair of 6V6 tubes .
Listen to “Surfin’ USA" and the great sounds of the Heartbreakers .
#10734 15 WATTS / 10" SPEAKER / ORIGINAL AA1164 CIRCUIT
’66 D-REVERB 22W AMP KITFamously clean, with enough guts to gig.Perfect for recording as well as performing, the D-Reverb produces stinging clarity that absolutely refuses to get lost in the mix .
One of the most popular designs ever, this amp lives in the happy middle between bright clarity and rich distortion . It excels in the studio and on the stage . While capable of crystal clear tones at good volume, you can push this one into beautifully saturated, play-sensitive distortion .
It’s all here: clarity, distortion, and rectifier tube sag .
#10737 22 WATTS / 12" SPEAKER / ORIGINAL AB763 CIRCUIT
H OU RS : 6
D I F F I C U LTY
H OU RS : 1 2
D I F F I C U LTY
H OU RS : 8
D I F F I C U LTY
H OU RS : 16
D I F F I C U LTY
’59 TWEED 15W AMP KITDirty little devil that shaped guitar history.With mysteriously fat saturated tone, this little monster makes it easy to achieve seismic distortion .
This amp’s 5E3 circuit is an enigma: Why do the controls on the channel you’re NOT using make your tone so great? The answer: Who cares? This is one of the greatest tone monsters ever created! Listen to Neil Young’s Rust Never Sleeps while building this kit .
Our most popular amp kit and a great learning experience .
#10731 15 WATTS / 10" SPEAKER / ORIGINAL 5E3 CIRCUIT
StewMac ICON KITS teach you the world of amp building, then turn you loose with amazing hand-built tone machines!
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’62 BRIT-PLEX 45W AMP KITThe original British showstopper.This amp started a revolution . It’s been rocking the world for over 50 years, and we still can’t get enough .
Favored by blues and rock players for exceptional sustain and rich creamy tone, the ’62 Brit-Plex is chock-full of harmonic gain, yet it still stays articulate and even a little crispy . Put this head on a classic 4x10 cab and watch out!
While building, listen to Gary Moore’s “Still Got The Blues ."
#10736 45 WATTS / ORIGINAL BRITISH CIRCUIT
’66 BRIT-74X 18W AMP KITLeave your half-stack at home.Born in London, this little blues blaster earns its living every night, gigging in clubs across the USA .
Launched in 1966, this amp quickly became a low-wattage holy grail . This is a stripped-down blues machine: two channels, one tone knob, no master volume . Buckle up and go where this gritty beast takes you! It comes with a footswitch to kick in the onboard tremolo .
Get the plexi tone without blowing the roof off the joint!
#10732 18 WATTS / 12" SPEAKER / ORIGINAL BRITISH CIRCUIT
’81 BRIT-800 50W AMP KITThis hairy monster lives to shred.The defining British circuit that dominated the ’80s .
This 50W giant created your favorite heavy rock and metal albums . Used by Slayer and Pixies, and recorded on early Metallica albums, this circuit produces that screaming guitar tone that your mother despises . With solid-state rectification there’s no sag, and the distortion created by this circuit is way more about treble than mids or bass .
Listen while building: Smashing Pumpkins’ Siamese Dream .
#10735 50 WATTS / ORIGINAL BRITISH CIRCUIT
’64 REVERB UNIT KITReverb you can’t get from a pedal.This is the unit that put the waves in surf music! Looks like an amp, sounds like a beach party .
This tube-driven reverb tank relies on good ol’ physics for a perfect effect . Your guitar signal travels along two large suspended springs to produce the reverb that launched the iconic surf sound . This isn't a pocket-sized digital simulation; this is the real deal!
Listen to Dick Dale’s “Misirlou" while doing this easy build .
#10733 ORIGINAL 6G15 CIRCUIT
H OU RS : 1 2
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H OU RS : 16
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Beginner-tested. Pro quality.StewMac ICON KITS are fun to build, with friendly instructions to guide you and loads of info to add to your knowledge.
stewmac.com 52 © 2019 StewMac
V5 EL34
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’62 BRIT-PLEX 45WA M P L I F I E R K I T O R I G I N A L B R I T I S H C I R C U I T
StewMac®
I C O N K I T S
DANGER: Unplug the amp before changing tubes.Tube locations from left to right:
5AR4(GZ34)
EL34 EL3412AX7(ECC83)
V6 V5 V4 V1
12AX7(ECC83)
12AX7(ECC83)
V3 V2
’62 BRIT-PLEX 45WA M P L I F I E R K I T O R I G I N A L B R I T I S H C I R C U I T
StewMac®
I C O N K I T S
DANGER: Unplug the amp before changing tubes.Tube locations from left to right:
5AR4(GZ34)
EL34 EL3412AX7(ECC83)
V6 V5 V4 V1
12AX7(ECC83)
12AX7(ECC83)
V3 V2
Cut this label on the dotted line with a razor knife and metal straightedge .Fasten it inside the cabinet using thinned wood glue or contact cement .
The duplicate copy below is included as a backup .
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tools + ideas for guitarmakingStewMac
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©2019 StewMac . All rights reserved .#10736 Updated March, 2019