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Service SourceK

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Service SourceK

OverviewLaserWriter 12/640 PS

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Overview About This Overview

About ThisOverviewThis overview brieflydescribes the servicingissues of the LaserWriter12/640 PS, especiallythose that distinguish it

from previous Apple laserprinters.

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Overview Options

OptionsThere are three options that are available for the Laser-Writer 12/640 PS: Duplexer unit

Face-up catch tray

500-sheet feeder (accommodates either standard orenvelope cassette)

Each of the options can be added independently of one anotherso there are several configurations that you mightencounter. The animation LW12/640 PS Options showshow the options go together.

LW 12/640 PS Options
http://lw12.640_ps_options.mov/

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Overview Paper Path

Paper PathThe printer has a basic S-shaped paper path and multi-purpose tray arrangement generally similar to the Laser-Writer 16/600 PS.

On the exit side of the fuser assembly, however, there is abrand new function: the paper deflector guide. Thissolenoid-actuated guide switches paper between one of two

paths. The inside path is the face-down delivery path thatcontinues straight up to the delivery rollers and output tray.The outside path serves three purposes.

Paper feed into the optional duplexer. Paper delivery to the optional face-up tray. If no options are attached, the outside path will feed

paper directly out the rear of the printer.

Note : The LW 12/640 PS Paper Path animation showsthe sequence of a duplex print job.

LW12/640 PS Paper Path
http://lw12.640_ps_paper_path.mov/

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Overview Duplexer

DuplexerThe most unique mechanical feature you will encounter isthe optional duplexer unit. The term duplex denotes twosided printing.

The duplexer is an L-shaped feeder that cradles theunderside and rear of the printer. When duplex printingselected through software, the paper deflector guide is

actuated and the sheet of paper diverts into the duplexer.There the paper is flipped and circulated back to the cassettefeed roller in preparation for its second imaging cycle.

The drive train in the horizontal leg of the duplexer receivdrive directly through an idler gear in the pickup drive

assembly in the printer. The feed roller at the entrance tothe duplexer also receives drive from the printer, but theother feed rollers in the vertical leg of the duplexer aredriven by the duplexer motor.

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Overview Face-Up Tray

Face-Up TrayThe face-up tray is an option that attaches to the rear of theprinter (or to the rear of the duplexer, if present).

This tray performs similarly to previous printers, exceptthat output to this tray is selected through software, not bythe setting of a lever. The presence of this tray is not senseby the controller.

OptionalFace-Up Tray

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Overview Duplex Scan Anomalies

Duplex Scan AnomaliesAfter side one prints during a duplex job, the paper parksitself onto a horizontal shelf beneath the cassette. Theduplexer motor then reverses direction. The trailing edge othe paper becomes the leading edge, and the paper exits theshelf and continues the path toward side-two printing.

Order of Scanning

Duplex documents stack in the face-down delivery tray incorrect book order (with odd-numbered pages facing down).To achieve this, page two is imaged during the first pass anpage one during the second pass.

Long Edge BindingThe reversing action of the duplexer flips the paper overalong its short axis. If you have chosen long edge binding

Scan/Feed DirectionsLong Edge Binding

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Overview Duplex Scan Anomalies

the software, the I/O controller flips the imaging dataaccordingly to counteract the reversal of the paper. The neteffect is even-numbered pages scanned in reverse.

For example, page 2 of a portrait oriented job images righto left from the bottom up. (This anomaly does not occurwith short edge binding). For this reason, be aware thatsome skew or image cutoff symptoms may appear to be 180degrees off from normally scanned pages.

Double-Page Batching

If there is enough buffer memory space available, thecontroller will image a print job four pages (two sheets) aa time. For example, the imaging order of an eight-pagedocument would be pages 2, 4, 1, and 3 (with sheets one antwo then being delivered), followed by pages 6, 8, 5, and(with sheets three and four delivered). This batchingfeature maximizes throughput speed.Sequence of

Double-Page Batching

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Overview Miscellaneous -

Miscellaneous

Fuser Pressure RollerThe fuser pressure roller provides an opposing surface tothe fuser heater roller, the same function as in previouslaser printers. However in the LaserWriter 12/640 PS,this pressure roller is seated in the chassis and is not a pa

of the fuser assembly itself.

Power Supply Assembly

The power supply assembly is a large multifunctionalcircuit board located in the lower section of the engine. In

addition to the DC power supply functions that are commonin previous engines, this assembly also houses some sensorsand switches, as well as the high-voltage power supply andvarious other functions.

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Beam Detection

Laser beam detection occurs outside of the laser/scanner

assembly, in the start-of-scan (SOS) sensor located in themirror assembly.

Two Shutters

There are two laser shutters, one inside the laser/scanner

assembly and one covering the mirror assembly. Both areactuated with the closure of the top cover.

Two "Exit" Sensors

Unlike previous printers, there are two paper sensors

downstream of the fuser assembly. The first is the fuserexit sensor that monitors the exiting of paper from the fuserassembly. The second is the delivery sensor that monitors

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paper after it passes the deflection guide in route to face-down delivery on top of the printer.

One Fan

There is only one fan in this printer.

Support for Heavy Paper

The LaserWriter 12/640 PS supports throughput of 50 lb.paper for simplex (single-sided) print jobs. You mustprint from the multipurpose tray and choose face-updelivery when using 50 lb paper.

RAM UpgradeThe LaserWriter 12/640 PS comes with 4 MB of RAM inrighthand of two SIMM slots. This amount does not allow

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duplex printing nor does it enable PhotoGrade. Upgrades arrequired if you want either of these additional features.

No SCSI

There is no SCSI support in the LaserWriter 12/640 PS.

Startup Page

The startup page is a single-sided page with a layout similto previous PostScript LaserWriter printers. The startuppage does report the presence of a duplexer or sheet feederbut will not recognize the optional face-up tray.

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Service Test Page

You may print a service t

page by jumperingconnector J101 on the I/Ocontroller board. Conse-quently, unlike previousprinters, the I/O controlleboard must be installed to

run a service test page.

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Top Cover Closure

The closing of the top cover initiates several more events

than in previous printers. They are listed below and aredescribed in detail in the Principles of Operation chapte

Actuation of cover interlock Opening of the laser shutter Opening of the mirror assembly shutter Latching of the top cover Pressing of the jam release plate Actuation of the toner cartridge latching mechanism Actuation of the fuser idler gear

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Service SourceK

Principles of OperationLaserWriter 12/640 PS

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Principles of Operation Print Process

Print Process

Print Process OverviewThe print process consists of the stages shown below, during which a toner image forms onthe drum surface, transfers and then bonds to the paper. Each sheet of paper passes throughsteps 4 to 6. During printing,the drum surface repeatedly cycles through steps 1 to 5, aswell as cleaning stage 7.

1Charging

2Exposure

3Development

Paper Enters

Xerographic Cycle

Cycle repeats for the next print

Paper Exit

5Discharge

7Cleaning

6Fusing

4Transfer

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Print Process Diagram and Paper Path

FuserRoller

PressureRoller Detack Saw

Transfer Roller

Paper

Laser Beam

CM Blade

Attraction Roller

CleaningBlade

BCR

1 Charging 2 Exposure

Drum

3 Development

4 Transfer5 Discharge

6 Fusing

7 Cleaning

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Print Process Description

1 Charging

During this stage, the drum surface receives a uniform negative charge.Note : The drum surface is made of a photoconductive material and the inner part of thedrum is made of a conductive material. This negative charge is actually placed onto theoutside surface of the photoconductor layer.

The charge is imparted by the bias charge roller (BCR) within the toner cartridge. The

BCR is a conductive roller in contact with the drum surface and is supplied with a discharvoltage by the high-voltage power supply (HVPS). The discharge occurs through the smallgaps between the BCR and the drum. The discharge voltage is an AC voltage with a negativeDC voltage superposed. The negative DC voltage is about -330 V. The AC voltage varieswithin the range of about 1.6 to 2.0 kVp-p with the discharge current since the AC currentis regulated to be constant.

Note : Before this stage, the drum surface will have been given a uniform negativecharge relative to the inner conductor of the drum (see Cleaning).

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2 Exposure

During this stage, the laser beam scans across the negatively charged drum surface.

The laser beam is emitted from the laser diode in the laser/scanner assembly. This diode isstationary. Its beam reflects off the face of a rapidly rotating scanning mirror, through acorrection lens, and outward off a stationary mirror which directs the beam onto thesurface of the drum.

The laser beam is modulated according to the video signal from the printer controller,switched on when the video signal denotes a black pixel and off when it denotes a white pix

The laser beam that strikes the drum surface generates electron-hole pairs in thephotoconductor layer, exciting electrons to the conduction band and thereby creating holesin the valence band. The electrons are attracted by the electric field and move toward theinner conductor of the drum to flow into it. The holes move toward the outside surface of thephotoconductor layer and recombine with the negatively charged electrons at the surface to

decrease the negative charge at the surface. The resultant less-negatively charged parts(parts whose potential has risen relative to the inner conductor) in the drum surface forman invisible electrostatic latent image.

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3 Development

During this stage, the electrostatic latent image on the drum surface attracts toner andforms a visible toner image.

The LaserWriter 12/640 PS uses nonconducting magnetic toner that readily transfers toplain paper. The toner is supplied from the toner compartment to the attraction rollerpositioned close to the drum within the toner cartridge. Because of its slight magnetism, thetoner is attracted to the surface of the attraction roller and is spread evenly into a very thinlayer by the charging and metering blade (CMB). This blade is made of silicone rubber.

it comes into contact with the toner, the resulting friction imparts a negative charge ontothe toner particles.

The attraction roller is covered with a thin conductive sleeve. A development bias (DB)voltage is applied to the conductive sleeve from the HVPS. The DB voltage is a negative DCvoltage with an AC voltage superposed. The DC voltage is about -250 V and the AC voltage

about 1.7 kVp.Since the attraction roller is kept at a potential of about -250 V DC relative to theconductor layer of the drum, the parts of the drum surface with the full negative chargehave a lower electric potential than the attraction roller, and the parts with decreasednegative charge have a higher electrical potential.

l f

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3 Development (cont.)

0 V

Development Bias

Attracting

The change of the electric potential of the drum surface while the drumsurface passes through the charging to the development steps

Charged Exposed Developed

a bc

i i l f O i i

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3 Development (cont.)

The diagram below illustrates the change of the potential as the drum surface passes fromthe charging through the development stages:.

1 Charging

Drum Surface Voltage

About -233VBias Charge

-V

-V

0

P i i l f O i P i P

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4 Transfer

During this stage, the toner transfers from the drum to the paper.

The bias transfer roller (BTR), referred to herein simply as the transfer roller, applies apositive charge to the back side of the paper as it feeds between the roller and the drum. Thetoner image transfers from the drum surface to the front side of the paper due to thispositive charge on the back side of the paper.

The paper is attracted by the negative charge induced in the inner conductor layer of thedrum by the positive charge of the paper and sticks to the drum surface.

Laser Beam


Drum

3 Development

P i i l f O i P i P

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5 Discharge

During this stage, the paper comes off the drum surface.

The detack saw applies a negative charge to the back side of the paper to neutralize thepositive charge previously applied by the transfer roller. The force which attracts thepaper to the drum surface disappears, and the paper releases naturally from the drum dueto gravity.

Laser Beam


Drum

3 Development

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Service SourceK

Specications


S ifi ti I t d ti 1

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Specifications Introduction - 1

IntroductionSpecifications information for this product can be found in this chapter and also in the SpecDatabase, which you can access in one of three ways:

Launch it directly by double-clicking the Apple Spec Database runtime alias at thetop level of the Main Service Source CD.

Select "Apple Spec Database" from the Service Source drop-down main menu.

Click the Acrobat toolbar icon for the database, which is near the right end of thetoolbar with the letters "SP."

Specifications Engine

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Specifications Engine -

Engine

Marking Engine Fuji Xerox P893 laser-xerographic

Laser Type: Semiconductor laser GaAlAsWavelength: 780 nmOutput power: 5 mW

Speed Simplex12 pages per minute maximum using A4-size paper.Actual speed depends on the images printed.

Duplex8 pages per minute maximum using U.S. letter-sizepaper. Actual speed depends on the images printed.

Life Expectancy(Printer)

Average number of prints between failure is 180,000 pages.


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Life Expectancy(Toner Cartridge)

Life expectancy is 6,000 pages when printing text documents withaverage page coverage (5% black). An example of a 5% blackpage coverage is a page consisting of double-spaced 14-point

courier type. Printing images and other graphics may impacttoner cartridge life expectancy.

Printing Materials 16- to 28-pound laser-quality bond (60 to 90 g/m 2 ); up to50-pound (190 g/m 2 ) stock when fed manually through the

multipurpose tray and delivered through the face-up outputtray. Accepts most textured and colored stock. Accepts medium-weight photocopier transparencies and labels. Envelopes can beprinted from the multipurpose tray or from the optionalenvelope cassette (sheet feeder only).

The paper used should not scorch, melt, transfer material, or

release hazardous emissions when heated to 200 C (393 F)for 0.1 seconds.


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Paper Sizes andCapacity

Supports U.S. letter, A4, B5, executive, and legal in the standardpaper cassette. The paper cassette holds 250 sheets of 20-pound (75 g/m 2 ) paper. The multipurpose tray can hold up to

80 sheets of standard U.S. letter paper, and other paper sizesfrom postcard up to U.S. legal. An optional 500-sheet cassetteis available that supports letter, A4, and U.S. legal-papersizes. An envelope cassette that can automatically feed up to 50envelopes is also available. The envelope cassette is compatibleonly with the 500-sheet feeder.


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Dimensions Printer onlyHeight 9.5 in. 24.2 cm)Width 15.9 in. (40.5 cm)

Depth 16.7 in. (42.4 cm)Printer with optional duplex printing unitHeight 11.89 in. (30.2 cm)Width 15.9 in. (40.5 cm)Depth 20.47 in. (52.0 cm)Printer with optional 500-sheet cassette and feederHeight 14.0 in. (35.6 cm)Width 15.9 in. (40.5 cm)Depth 16.7 in. (42.4 cm)Printer with optional duplex printing unit and 500-sheet

cassette feederHeight 16.2 in. (41.1cm)Width 15.9 in. (40.5 cm)Depth 20.4 in. (52.0 cm)


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Weight Approximately 30 lb. (14 kg)

VoltageRequirements

U.S.103.5 to 126.5 VAC, 58 to 62 HzEurope/Australia198 to 264 VAC, 48 to 52 Hz

Note : The LaserWriter 12/640 PS printer does not contain auniversal power supply or fuser assembly.


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Power Consumption Energy-saving mode26 WStandby average

100/120 V, approximately 125 W220/240 V, approximately 120 WOperating average110/120 V, approximately 390 W220/240 V, approximately 370 WMaximum power consumption

110/120 V, approximately 790 W, 6.8 A220/240 V, approximately 770 W, 3.5 A

Specifications I/O Controller - 8

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I/O Controller

Microprocessor AMD Am29040 30-MHz RISC microprocessor

ROM 4 MB (including 35 Type 1 fonts)

RAM 4 MB (expandable to 64 MB)72-pin, 70 ns or less SIMMs are required. See Upgrades for

full information about possible configurations.

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Specifications I/O Controller 10

Grayscale Imaging Standard85 lines/inch dithered halftone, 101 gray levels106 lines/inch dithered halftone, 129 gray levels

141 lines/inch dithered halftone, 73 gray levelsPhotoGrade (12 MB of RAM required)

85 lines/inch halftone, 201 gray levels106 lines/inch halftone, 257 gray levels141 lines/inch halftone, 145 gray levels

Languages PostScript Level 2 (2015)PCL5 (LaserJet IIID emulation)


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Fonts on Disk Sixty-four fonts are provided with the LaserWriter 12/640 PS,including such fonts as ITC Avant Garde , ITC Bookman ,Chicago, Courier, Delphian, Garamond Condensed, Geneva,

Helvetica , Helvetica Black, Helvetica Compressed, HelveticaNarrow, Lubalin Graph, Lucida Bright, Machine, Monaco,Nadianne, New Century Schoolbook, New York, Old EnglishText, Onyx, Oxford, Palatino , Swing, Symbol, Times , ITCZapf Chancery , ITC Zapf Dingbats , and Zeal.


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Fonts in ROM

PostScript The following fonts are resident in the printer ROM:

AvantGarde Book, AvantGarde BookOblique, AvantGarde Demi,AvantGarde DemiObliqueBookman Demi, Bookman DemiItalic, Bookman Light, Bookman

LightItalicCourier, Courier Bold, Courier BoldOblique, Courier ObliqueHelvetica, Helvetica Bold, Helvetica Bold Oblique, Helvetica

Narrow, Helvetica Narrow Bold, Helvetica NarrowBoldOblique, Helvetica Narrow Oblique, Helvetica Oblique

NewCentury Schoolbook Bold, NewCentury Schoolbook BoldItalic,NewCentury Schoolbook Italic, NewCentury Schoolbook Roman

Palatino Bold, Palatino BoldItalic, Palatino Italic, Palatino RomanSymbolTimes Bold, Times Bold Italic, Times Italic, Times RomanZapf Chancery MediumItalicZapf Dingbats


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PCL The following PCL fonts are resident in the printer ROM:Times Roman, Time Bold, Time Italic, Times Bold ItalicUnivers Medium, Univers Medium Bold, Univers Medium Italic,

Univers Medium Bold ItalicCourier 12 pitch, 10 point Medium; Courier 12 pitch, 10 point

Bold; Courier 12 pitch, 10 point Italic; Courier 10 pitch, 12point Medium; Courier 10 pitch, 12 point Bold; Courier 10pitch, 12 point Italic

Line Printer Font 16.67 pitch, 8.5 point, Medium

Specifications Environmental Information - 14

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Specifications Environmental Information 14

Environmental Information

OperatingTemperature

50 to 90 F (10 to 32 C)

Operating Humidity 15 to 80 percent RH non-condensing

Storage (TonerCartridge)

Temperature 32 to 95 F (0 to 35 C)Humidity 15 to 85 percent RH non-condensing

Storage (Printer) Temperature 32 to 122 F (0 to 40 C)Humidity 35 to 85 percent RH non-condensing

Specifications Finished Goods Accessories - 15

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p

Finished Goods Accessories

Ethernet Apple Ethernet Thin Coax Transceiver M0329Z/BApple Ethernet Twisted Pair Transceiver M0437Z/BApple Ethernet AUI Adapter M0432LL/A

Toner Cartridge LaserWriter 12/640 PS Toner Cartridge M4683G/A

Printer Options LaserWriter 12/640 PS 500-Sheet Feeder M4682G/A (includesstandard 500-sheet cassette). Envelope cassette M4680G/A isalso available for the sheet feeder.

LaserWriter 12/640 PS Face-Up Output Tray M4698G/ALaserWriter 12/640 PS Duplex Printing Unit M4697G/A

Principles of Operation Print Process -

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p p

7 Cleaning

During this stage, any residual toner on the drum is cleaned off to prepare for the nextprint cycle.

The residual toner is collected in a special compartment separate from the fresh tonercompartment. The transfer rate is more than 90%, but varies according to the percentageof printed pixels and the environmental conditions such as temperature and humidity.Residual toner cannot be re-used.

Toner Cartridge

Cleaning Blade

BCR

Principles of Operation Paper Transportation -

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p p p p

Paper Transportation

Paper Path FlowchartThe chart below shows the parts that feed paper through the LaserWriter 12/640 PSengine. Parts are shown in the order in which they occur during a print cycle.

Cassette FeedPickup Roller

Pickup Roller(Optional Sheet Feeder)

Cassette Feed Roller

Manual FeedPickup Roller

Preregistration Feed and Pinch Rollers

Principles of Operation Paper Transportation -

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p p p p

Paper Path DiagramThe cross-sectional diagram below illustrates the elements indicated in the previous chart.The roller diameters are listed below the diagram.

Fuser Roller

DeliveryPinch Roller

Pressure Roller

Fuser Exit Roller

Fuser Pinch Roller

Drum

Cassette


RegistrationTransferCassette FeedR ll

Cassette FeedPinch Roller

PreregistrationFeed Roller

PreregistrationPinch Roller

Delivery Roller Registration Pinch Roller

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Principles of Operation Print Image Creation -

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Laser/Scanner Assembly Structure and OperationThe laser light source used for the LaserWriter 12/600 PS is a semiconductor laser diode(LD) with a rated maximum output power of 5 mW.

The laser diode is switched on and off according to the video signal. The power of the laselight is monitored and controlled by the monitor circuit so that it remains constant.

The laser light from the diode is aimed directly at a hexagonal mirror that is being rotatedat a very high speed by the scanner motor. The six facets of the mirror reflect the laserbeam in turn as the mirror rotates.

The beam reflected by the hexagonal mirror passes through a correction lens and outwardfrom the laser/scanner assembly. The beam reflects downward off a stationary mirror andthrough a slit in the toner cartridge, striking the surface of the photosensitive drum.

At the beginning of each scan, the laser beam strikes the start-of-scan (SOS) sensor. Theon and off switch of the laser light is determined by the signal from the SOS sensor.

Start-of-Scan (SOS) Sensor

Principles of Operation Print Image Creation -

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Note : One horizontal line of an image is drawn by scanning the pulsating laser beamacross the drum. The timing and location of the pulse is a function of the VIDEO signoriginating from the I/O controller board. By rotating the drum and scanning

additional lines, a two-dimensional image is built. The resolution of a laser printerdetermined by the number of pixels per inch (in the horizontal direction) and thenumber of scans per inch (in the vertical direction). The LaserWriter 12/640 PShas a resolution of 600 x 600.

600 scans/inch

Direction of Paper

Principles of Operation Mechanical Drive -

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Mechanical DriveThe generation and transmission of mechanical drive in the LaserWriter 12/640 PS is

shown in the diagram below.

Pickup Motor

Main Motor

Gear cluster in thepickup drive assemblytransmits the driveforce to the rollersshown to the right.

CassettePickup Roller

RegistrationFeed Roller

CassetteFeed Roller

PreregistrationFeed Roller


Gear cluster in themain drive assembly


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1 Pickup Motor Mechanical Drive (Part 1 of 2)

The drive force generated by the pickup motor is transmitted to the cassette andpreregistration feed rollers and to the cassette feed clutch gear via the pickup drive

assembly. The rotation of the cassette pickup roller is controlled by the cassette feed clutchgear and the cassette feed solenoid.

Pickup MotorPickup Drive Assembly

PreregistationFeed Roller

Cassette FeedClutch Gear


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2 Pickup Motor Mechanical Drive (Part 2 of 2)

The drive force generated by the pickup motor is also transmitted to the manual feed clutchgear via the pickup drive assembly. The rotation of the manual feed pickup roller is

controlled by the manual feed clutch gear and the manual feed solenoid.

Manual Feed Solenoid Pickup Motor

Pickup Drive Assembly

Manual Feed Pickup Rolle


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3 Main Motor Mechanical Drive (Part 1 of 3)

The drive force from the main motor is transmitted to the registration feed roller via themain drive assembly.

Registration Feed Roll

Registration Pinch Roller


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The drive force from the main motor is also transmitted throught the main drive assemblyto the photosensitive drum, and from the drum to the transfer roller.

Photosensitive Drum


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The drive force from the main motor is also transmitted to the fuser roller drive gear andthe delivery assembly drive gear via the drive transfer assembly. When the toner cartridge

is removed, the idler gear opens the path of drive force transmission, thus cutting offmechanical drive to the fuser assembly.

Drive Transfer Assembly

Idler Gea

Delivery Roller Shaft

Toner Cartridge

Delivery AssemblyDrive Gear

Principles of Operation Function of Major Components -

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Function of Major ComponentsThe function of the major components of the LaserWriter 12/640 PS is briefly described

below. The components are divided into the following seven blocks, which correspond to theexploded views that appear in the exploded view chapter.

Cassette (Deck 1)

Paper Transport

Fusing and Paper Exit

Drive & Xerographic

Electrical

Frame

Cassette (Deck 1)

Paper Cassette

The cassette holds cut sheets of plain paper. Envelopes must be fed from the multipurposet th ti l l tt d t d t b f d f th lti


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Cassette (Deck 1)

Paper Cassette

Mi i h Principles of Operation Function of Major Components -

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Paper Transport (1 of 2)

Pickup Drive Assembly

The pickup drive assembly is responsible for mechanical drive to the cassette and manualfeed pickup rollers and to the cassette and preregistration feed rollers. It is powered by thepickup motor. Contained within the assembly itself are the two feed rollers and the cassettefeed solenoid.

Main Drive Assembly

The main drive assembly is responsible for all mechanical drive from the registrationroller through paper delivery. It is powered by the main motor.

Drive Transfer Assembly

The drive transfer assembly is the gear train that transfers mechanical drive from themain motor to the fuser assembly, delivery roller shaft, and photosensitive drum. An idlergear is located along the path of the drive force transmission to the fuser. The idler gearcloses the path when the toner cartridge is installed

Registration Feed Roller

The registration feed roller, which is driven by the operation of the main drive assembly,f d i t ith th gi t ti i h ll Th i h ll i i g l d d

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Multipurpose Frame Assembly

The multipurpose frame assembly includes the manual feed solenoid, manual feed clutchgear, manual feed pickup roller, separation pad, and the manual feed paper-present sensorand actuator.


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Manual Feed Solenoid

Manual FeedClutch Gear

Manual Feed Paper-PresentActuator

Multipurpose FrameAssembly


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Fuser Assembly

The major parts contained within the fuser assembly include the fuser heater bulb, fuserroller, thermostat, fuse, and temperature sensor assembly.

The fuser heater bulb is located inside the fuser roller. Power to the bulb is switched onand off so that the temperature of the fuser roller surface is kept constant. When thetemperature of the fuser rises to the predetermined upper limit temperature, the powersupply is switched off. This safeguard is known as first-stage overheat protection.

The fuser roller applies the heat for melting and fusing the toner to paper. It is connected tothe frame ground through a diode so that negative charge flows, thereby preventing thetoner image from being disturbed during the fusing process.

The thermostat is a part of the fuser bulb circuit and provides the second-stage overheatprotection. If the first-stage overheat protection fails to prevent overheat and thethermostat reaches the predetermined temperature, the contacts of the thermostat open tobreak the circuit between the fuser bulb and the power supply.The fuse is also a part of the fuser bulb circuit and provides the third-stage overheatprotection. If the first and second stage protection both fail to prevent overheat and the fuse


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Fuser Assembly

Delivery Rollers

Fuser Exit Actuator

Fuser Exit Sensor

TemperatureSensor Assembly

Fuser Roller

Thermostat

Fuse


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Drive and XerographicFor full description of the components in this section, see the Print Image Creation topic

Laser/Scanner Assembly

The laser/scanner assembly includes the laser diode, scanner, lenses, and mirrors.

Note : The laser/scanner assembly is a precision optical system. Never open thecover. Touching the parts may result in permanent damage to the components.

Mirror Assembly

The mirror assembly includes the start-of-scan sensor (SOS) and the stationary mirrorthat reflects the beam from the scanner mirror onto the photosensitive drum.

Toner CartridgeThe toner cartridge consists of a photosensitive drum and a toner container integrated intoone unit. It includes the following major components.

Photosensitive Drum

Bias Charge Roller (BCR)

Attraction Roller


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Drive and Xerographic (1 of 2).

Mirror Assembly

bl

Toner Cartridge


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Drive and Xerographic (2 of 2)

Lens L1

Collimator Lens Mirror M1

Laser/Scanner Assembly

Start-of-Scan Sensor (SOS)

Mirror AssemblyHexagonal Mirror

Cylinder Lens

Laser Diode


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Electrical

Power Supply AssemblyThe power supply assembly is a large multifunctional circuit board located in the lowersection of the engine. Listed below are its major components.

Low-voltage power supply (LVPS): The LVPS generates stabilized DC voltages of 5 V,12 V, and 24 V and supplies these voltages to the electrical components of the printer.

High-voltage power supply (HVPS): The HVPS generates AC and DC high voltages forcharge, development, transfer, and discharge in the print process. Those voltages aresupplied to the bias charge roller, attraction roller, transfer roller, and detack saw.

Interlock switch: This switch opens the supply circuits of 24 VDC and 5 VDC (+B)driving the laser diode.

Cassette paper-present sensor: This sensor is actuated by the cassette paper-presentactuator and detects when the cassette runs out of paper.

Power inlet: The power inlet is hard-wired directly to the circuit board.

DC Controller BoardThe DC controller board controls the whole operation of the printer. Listed below are its

f Principles of Operation Function of Major Components -

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Electrical

I/O Controller BoardDC Controller Board

PowerInlet

Power SupplyAssembly

Fan


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FrameWhen the top cover closes, the seven events described below take place.

Cover Interlock Actuator

Top cover closure actuates the interlock switch on the power supply assembly. There arethree components that work together to actuate this switch.

Top cover actuator: The thin plastic post built into the top cover.

Spring-loaded actuator: The vertical assembly that transfers actuation downward.

Actuator arm: The arm that contacts the interlock switch on the power supplyassembly.

Laser Shutter

A plastic post built into the top cover extends through a cutout in the top of the laser/scanner assembly. The laser shutter facing the mirror assembly opens, thus allowing thelaser beam to leave the laser/scanner assembly.

Mirror Assembly Shutter

A plastic post built into the top cover presses open the shutter that covers the mirrorassembly Unless this shutter and the one above are in an open position the laser can not


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Frame

Fuser IdlerGear Actuation

Cover InterlockActuator

Mirror AssemblyShutter

Toner CartridgeLatching Mechani


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General Wiring Diagram

Fuser Assembly

P/J285

DeliverySensor

Fuser ExitSensor

Fuser HeaterThermistor

P/J281

STS2 STS1

J292

P/J291

P/J29

LN

FG

P/J11

I

F

MainSwitch

CoverInterlockSwitch P/J222

Preregistration

14

7

3 3

2 2

P/J28

2

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Service SourceK

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Troubleshooting


Troubleshooting About the Status Panel -

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About the Status PanelThe LaserWriter 12/640 PS has a status panel that consists ofthree LEDs. The status reported through the LEDs is generated bythe I/O controller board based upon signals that the board receivesfrom the printer sensing system and other engine monitoringmechanisms. There are two types of reporting.

End-user reporting consists of LED arrays that can beobserved by end users without need of special tools. This type of

reporting can be broken down into POST and PostScriptreporting (see following topics).

Service technician reporting consists of LED arrays that canonly be observed through the use of a special tool. Thisreporting is also referred to as EPOST (see topic later in thischapter). Whereas end-user reporting can help you introubleshooting over the phone, EPOST requires that you be atthe printer location.

Ready

PaperOut

PaperJam

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POST (Power-On Self Test)When you switch on power, all the status panel LEDs illuminatebriefly. This confirms that power is getting to the status panel andthat all LEDs are operational. All LEDs then extinguish and comeback on. This marks the start of POST.

POST is a set of diagnostic procedures that are written intofirmware on the I/O controller board. POST executes in the first10 seconds of startup and checks the following three areas of theprinter in order:

Stage 1 I/O controller (ROM & SIMMs)

Stage 2 I/O controller (miscellaneous circuitry)

Stage 3 D/C controller board

Troubleshooting POST (Power-On Self Test)/Stage Failure/POST - 3

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Stage Failure/POST

POST extinguishes the LEDs from top to bottom as each test stagepasses. (The Ready LED is considered here to be the top LED). Infunctional printer, the testing process takes about 40 seconds,after which control passes to PostScript code in ROM and thenormal warm-up continues (see PostScript Reporting in thischapter).

However, if POST detects a fault during any stage, the status panelenters an error state and flashes the bottom two LEDs forever.Making note of the stage from which this error array firstappears can help you choose the modules to bring on a service call

For example, suppose failure occurs during stage two (only thetop LED had extinguished before the error array appears). Thisindicates an I/O board failure, so a replacement board shoulddefinitely accompany you on site.

POST Example

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PostScript ReportingPostScript reporting starts as soon as POST is completed. Most ofthe time, PostScript will report according to the literaldesignation of the LED. (For example, the paper-out LEDilluminates when the paper cassette is empty). However, thereare some instances where closer observation is critical ininterpreting the status panel.

Solid ready light: In some cases, the ready light will illuminat

for as long as 15 seconds before a PostScript fault is reported.Make sure to wait this extra time for PostScript to executebefore shutting down to perform further troubleshooting.

Behavior before PostScript error: As with stage-reportingduring POST, it is sometimes necessary to note what occursbefore the error array first appears. The chart on thefollowing page notes where this is important.

Troubleshooting PostScript Reporting/End-User Error Codes - 5

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End-User Error Codes

Ready LED on

Paper-Out andPaper-Jam LEDsflash

Description Explanation

Printer is ready

An error has been detected in POST. Observationof LED behavior prior to this array can isolate thefault to one of three general area (see "POST") 2 .

The top cover is open.

No paper or cassette is not installed 3 .

Array

All LEDs off

Paper-Out LEDilluminates

Ready LED flashes Printer is warming up or processing a job 1 .

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EPOST (Extended Power-On Self Test)EPOST behaves exactly like POST in that it checks the same threeareas in the same order and displays an error array if a fault isdetected. However, EPOST has more extensive testing and its errorarrays are completely different. When a fault is detected duringEPOST, all LEDs extinguish and the status panel will loop througthe following sequence until you switch off power:

All LEDs On for approximately one second

All LEDs Off for approximately one second EPOST Error Code for approximately one second

All LEDs Off for approximately two seconds, then repeat loop

If no error is detected by EPOST, an EPOST test page will printbefore control is passed on to the PostScript interpreter (if aduplex unit is attached, two double-sided pages will print).


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Initiating EPOST

To initiate EPOST, you must have the printer rollback test plug(P/N 922-1489). This test plug is colored bright green to

differentiate it from the older version black plug. Do not use theblack plug on the LaserWriter 12/640 PS. It wont harmanything; it just wont work.

Switch off the printer and install the test plug into the LocalTalkport on the back of the I/O controller board. Switch the printer

back on.


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Stage Failure/EPOST

An EPOST error code can either illuminate solidly (for I/Ocontroller failures) or flash (for engine failures). The chart on

the next page shows the possible error arrays. The EPOSTExample animations demonstrate two of the combinations.

The Example 1 animation simulates an I/O board error. Noticehow the EPOST announcement sequence (all LEDs on for a secondthen all LEDs off for a second) is followed by a paper jam LED

illuminates solidly for about a second.

The Example 2 animation simulates a DC controller boarderror. Notice how the EPOST announcement sequence is followedby a paper jam LED that flashes for about a second.

EPOST Example 1

EPOST Example 2

Troubleshooting EPOST (Extended Power-On Self Test)/EPOST Error Codes -

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EPOST Error Codes

All LEDs on for a second, then off for a second, followed by aone-second display of...

...Flashing Jam LED= DC Controller Board Error

...Flashing Out LED= Fuser Assembly Error

...Flashing Jam & Out LEDs= Laser/Scanner Error

...Flashing Ready LED= Fan Error

...Solid Jam LED= I/O Controller Board Error

...Solid Jam & Out LEDs= ROM (I/O Controller) Error

...Solid Ready LED= General SIMM Error

FLASH

FLASH

FLASH

FLASH

FLASH

Troubleshooting Cleaning the Mirror -

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Cleaning the MirrorThere is a small peach-colored square cleaner built into the

mirror assembly. Slide this square back and forth to removeparticles from the mirror.

MirrorCleaner

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Troubleshooting Duplexer Jams -

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fail to install this guide properly, jamming will frequently occuas paper enters the duplexer from the printer. Be sure that thetwo locking connectors are also fully snapped into place.

Locking Connectors

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If accordion-style jamming still occurs in the duplexer afterproper installation of the paper guide, replace the verticalduplexer assembly (P/N 922-2001)

Troubleshooting Printing with 8.3 Driver/EPOST Error Codes - 1

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Printing with 8.3 DriverFor purposes of troubleshooting paper feed, you can print with theLaserWriter 8.3 driver from Mac OS computers. Simply copy thePPD for the LaserWriter 12/640 PS into the PrinterDescriptions folder in the System Folder, select the printerthrough the Chooser, and click on Setup.

You can print duplex jobs by clicking on the Options button in thprint dialog and making the appropriate selection. However, youcannot print to the face-up tray with the 8.3 driver.

Note : The LaserWriter 12/640 PS PPD is available on the June1996 Service Source CD (path: Service Source:ServiceManuals:Clips).

Troubleshooting Out of Paper in Multipurpose Tray -

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Out of Paper in Multipurpose TrayIf you are trying to print from the standard cassette and get anerror message saying that there is no paper in the multipurposetray, the problem may be in cassette setup.

There is a paper-length guide at the end of the cassette that mustbe adjusted for letter size paper (the position as shipped is for A4paper). When the AutoSelect feature built into PostScriptsearches for letter size paper, the cassette will be passed over andthe controller assumes that the paper should be in themultipurpose tray.

To rectify this situation, make sure that the length guide isadjusted for letter size paper, see the next page for the graphic.

Troubleshooting Out of Paper in Multipurpose Tray/EPOST Error Codes - 1

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.

Length Guidein Letter Position

Troubleshooting Multipurpose Tray Paper Jams - 1

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Multipurpose Tray Paper JamsThere have been a number of reported problems with themultipurpose tray and its associated components. In the process ofresolving these problems, service providers may inadvertentlydislocate the solenoid flapper or actuator that is responsible forreleasing the multipurpose tray paper pickup roller so that it cancomplete its paper pickup cycle. When this occurs the paperpickup roller rotates constantly resulting in paper jams (if paperis present) and annoying noises whenever the printer is beingused. Correcting the problem requires a service call.

Refer to the Multipurpose Tray Paper Jams pdf. file for therepair procedure.

Troubleshooting Testing the Print Engine without the I/O Board - 1
http://lw_12.640ps-mp_tray.ss.pdf/http://lw_12.640ps-mp_tray.ss.pdf/http://lw_12.640ps-mp_tray.ss.pdf/http://lw_12.640ps-mp_tray.ss.pdf/

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Testing the Print Engine without the I/OBoard

Remove the I/O board. The DC Controller interface connects to theback of the I/O board. Just below this interface board is a metalplate which has a grid etched into it. This grid is the key to thepins located on the interface just above it.

On the DC controller interface, locate the pin marked TP (test

print). Jumper the pin TP to one of the pins marked G(ground). Be careful to jumper the correct pins since some pinscarry DC voltage.

You can also try forcing a test print without removing the I/O bstarting with the test print pins (on the I/O board) jumpered, and

then applying power. If you start with the pins jumpered beforeturning the printer on, this should bypass the power-on self test.

Troubleshooting False Paper Jam Error with Startup Page - 1

l h

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False Paper Jam Error with Startup PageSymptom: A false paper jam error occurs when theLaserWriter 12/640 tries to print the startup page. No paper ispicked up. EPOST reports a DC Controller error. When the DCcontroller board is replaced, the problem remains. Uponinitiating a service test print, the motor will spin for about asecond and then will stop with no test page output.

Discussion : Observe the pickup solenoid through the small holin the shield that covers the pickup drive assembly, and initiate aservice test print. You should see the pickup motor spin, and abouta second later see the solenoid trigger. If it does not, you eitherhave a bad solenoid, bad cassette size sensor board, or a bad cablethat runs between the solenoid and the sensor board. In the case ofthe bad cassette size sensor board, it can cause EPOST to display aDC controller error.

T bl h ti g P i t Q lit P bl 1

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Troubleshooting Print Quality Problems - 1

Image Quality ProblemsIt can be easily determined whether an image quality problem is being caused by the print engine or by the

I/O controller board by producing a service test page. The service test page can be generated by jumper-ing the two pins of connector J101 on the I/O controller board.

If the test page is normal, but the regular prints have an image quality problem, the problem is probablywith the I/O controller board. If the test print has also the image quality problem, the problem is probablyin the print engine.

When troubleshooting an image problem, produce a test print using letter size or A4 paper, exactly iden-tify the symptom, and isolate the problem by referencing the accompanying troubleshooting tables.

If the tables do not lead you to a solution to the problem, examine each part listed in the initial analysis of

the table corresponding to the problem. The fault is probably among those parts. Replace the part or partsthat in your judgment will most likely resolve the problem.

Roller DiametersFor a listing of the diameters of the rollers in the LaserWriter 12/640 PS, see page 13 in the Principles ofOperation chapter. Knowing these diameters can assist in troubleshooting repetitive horizontal printdefects.

List of Troubleshooting TablesThe troubleshooting tables cover the following typical fourteen image quality problems:

Table P-1 Light PrintsTable P-2 Blank PrintsTable P-3 Black Prints

Troubleshooting Print Quality Problems 2

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P-1 Light Prints

Step Actions and Questions Action(When There Is Problem)

1111 Paper conditions (moisture, warp, etc.)Is the problem solved if you use new sheets of paper?

Replace the paper. Advisethe customer to stock paperin a dry place.

2222 Toner cartridgeIs the problem solved by replacing the toner cartridge with anew one?

Replace the toner cartridge.

3333 Dirty reflecting mirrorIs the problem solved if you use the peach-colored slider(built into the mirror assembly) to wipe the mirror clean?

Clean the mirror.

4444 Drum ground Restore the continuity of thed d h

ProblemThe overall image density is lighter than normal.Initial AnalysisInspect the following components. Are they compatible with your printer ver-sion, correctly installed, not damaged, deformed or contaminated, or free offoreign objects sticking? Toner Cartridge Power Supply Assy Transfer Roller Assy Mirror Assembly Laser/Scanner Assy DC Controller Board Fuser Assembly Fuser Pressure Roller Static Eliminator Top Cover


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P-2 Blank Prints




2222 Drum ground

Is the toner cartridge drum grounded securely?* Check the drum ground path: drum > drum shaft pin >

Restore the continuity of the

drum ground path.

3333 Laser beam pathAre there obstructions or contamination on the laser beampath from the laser/scanner assembly to the Drum?

Remove the obstructions orcontamination.

ProblemThe entire print is blank.Initial AnalysisInspect the following components. Are they compatible with your printer version,correctly installed, not damaged, deformed or contaminated, or free of foreignobjects sticking? Toner Cartridge Power Supply Assy Transfer Roller Assy Mirror Ass embly Laser/Scanner Assy DC Controller Board Fuser Assembly Fuser Pressure Roller Static Eliminator Top Cover


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P-3 Black Prints




2222 ChargingUse a sheet of paper to cover the window through which thelaser beam is emitted from the laser/scanner assembly.Does the problem still occur?

Replace power supplyassembly. If problempersists, replace DCcontroller board.

3333 Laser/scanner assyUse a sheet of paper to cover half of the window throughwhich the laser beam is emitted from the laser/scannerassembly

Replace laser/scannerassembly. If problempersists, replace DCcontroller board.

ProblemThe entire print is black.Initial AnalysisInspect the following components. Are they compatible with your printer version,correctly installed, not damaged, deformed or contaminated, or free of foreignobjects sticking? Toner Cartridge Power Supply Assy Transfer Roller Assy Mirror Ass embly Laser/Scanner Assy DC Controller Board Fuser Assembly Fuser Pressure Roller Static Eliminator Top Cover


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P-4 Vertical Band Deletions


1111 Dirty reflecting mirrorIs the problem solved if you use the peach-colored slider(built into the mirror assembly) to wipe the mirror clean?

Clean the mirror.





ProblemThere are areas of the image that are extremely light or missing entirely. These

missing areas form wide bands that run vertically along the page, in the directionof paper travel.Initial AnalysisInspect the following components. Are they compatible with your printer ver-sion, correctly installed, not damaged, deformed or contaminated, or free offoreign objects sticking? Toner Cartridge Power Supply Assy Transfer Roller Assy Mirror Assembly Laser/Scanner Assy DC Controller Board Fuser Assembly Fuser Pressure Roller Static Eliminator

Top Cover


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P-5 Horizontal Band Deletions



Replace the paper. Advisethe customer to stockpaper in a dry place.

2222 Toner cartridge

Is the problem solved by replacing the toner cartridge with a newone?

Replace the toner

cartridge.

3333 Charging and developmentIs the toner image on the drum normally developed?* Switch off the printer power while the development is inprogress, and visually check the toner image on the drum (the area


ProblemThere are areas of the image that are extremely light or missing entirely. These

missing areas form wide bands that run horizontally across the page and parallelwith the direction of paper travel.Initial AnalysisInspect the following components. Are they compatible with your printer ver-sion, correctly installed, not damaged, deformed or contaminated, or free offoreign objects sticking? Toner Cartridge Power Supply Assy Transfer Roller Assy Mirror Ass embly Laser/Scanner Assy DC Controller Board Fuser Assembly Fuser Pressure Roller Static Eliminator

Top Cover


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8888 TransferIs the toner image on the drum transferred normally on the paper?* Switch off the printer power while the transfer is in progress,and visually check the toner image on the drum.


9999 Fuser heater roller and fuser pressure rollerAre there scratches, contamination, or foreign objects on thefuser heater roller or the fuser pressure roller?

Replace the roller.



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P-6 Vertical Streaks




2222 Paper path

Are there obstructions such as burrs or objects or contami-nation on the paper path?

Remove the obstructions orreplace the component.

3333 Laser beam pathAre there obstructions or contamination on the laser beampath from the laser/scanner assembly to the Drum?

Remove the obstructions orcontamination.

4444 Laser/scanner assy Replace laser/scanner

ProblemThere are black lines running vertically along the page.

Initial AnalysisInspect the following components. Are they compatible with your printer version,correctly installed, not damaged, deformed or contaminated, or free of foreignobjects sticking? Toner Cartridge Power Supply Assy Transfer Roller Assy Mirror Ass embly Laser/Scanner Assy DC Controller Board Fuser Assembly Fuser Pressure Roller Static Eliminator Top Cover


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P-7 Horizontal Streaks




2222 Drum groundIs the toner cartridge drum grounded securely?* Check the drum ground path: drum > drum shaft pin >

Restore the continuity of thedrum ground path.

3333 ChargingUse a sheet of paper to cover the window through which thelaser beam is emitted from the laser/scanner assembly.Does the problem still occur?


ProblemThere are black lines running horizontally across the page.

Initial AnalysisInspect the following components. Are they compatible with your printer ver-sion, correctly installed, not damaged, deformed or contaminated, or free offoreign objects sticking? Toner Cartridge Power Supply Assy Transfer Roller Assy Mirror Assembly Laser/Scanner Assy DC Controller Board Fuser Assembly Fuser Pressure Roller Static Eliminator Top Cover


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P-8 Spot Deletions




2222 Charging and developmentIs the toner image on the drum normally developed?* Switch off the printer power while the development is inprogress, and visually check the toner image on the drum (thearea upstream of the transfer step).

Replace power supplyassembly. If problem

persists, replace DCcontroller board.

3333 Transfer roller assemblyAre there foreign objects or contamination on the rollerportion of the transfer roller assembly?

Replace the transfer rollerassembly.

ProblemThere are areas of the images that are extremely light or missing entirely. These

missing areas form spots that are localized to small areas of the page.Initial AnalysisInspect the following components. Are they compatible with your printer ver-sion, correctly installed, not damaged, deformed or contaminated, or free offoreign objects sticking? Toner Cartridge Power Supply Assy Transfer Roller Assembly Laser/Scanner Assy Mi rror As sembly Fuser Assembly Fuser Pressure Roller


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g Q y

P-9 Spots





Replace power supplyassembly. If problempersists, replace DC

controller board.

3333 Transfer roller assemblyAre there foreign objects or contamination on the rollerportion of the transfer roller assembly?

Replace the transfer rollerassembly.

ProblemThere are spots of toner all over the page.

Initial AnalysisInspect the following components. Are they compatible with your printer ver-sion, correctly installed, not damaged, deformed or contaminated, or free offoreign objects sticking? Toner Cartridge Power Supply Assy Transfer Roller Assembly Laser/Scanner Assy Mirror Assembly Fuser Assembly Fuser Pressure Roller


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g Q y

P-10 Residual Image





Replace power supplyassembly. If problem

persists, replace DCcontroller board.

3333 Transfer roller assemblyA th f ig bj t t i ti th ll

Replace the transfer rollerassembly

ProblemThere are ghosted images appearing on the page.

Initial AnalysisInspect the following components. Are they compatible with your printer ver-sion, correctly installed, not damaged, deformed or contaminated, or free offoreign objects sticking? Toner Cartridge Power Supply Assy Transfer Roller Assy Mirror Ass embly Laser/Scanner Assy DC Controller Board Fuser Assembly Fuser Pressure Roller Static Eliminator Top Cover

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g y

P-12 Skewed Image


1111 Paper feedIs the paper cassette installed correctly, and is the papercorrectly loaded?

Reload the paper and rein-stall the cassette.

2222 Paper pathAre there obstructions such as burrs or foreign objects orcontamination on the paper path?


3333 Feeder rollerDoes the feeder roller feed the paper correctly?

Replace the feeder roller.

4444 Paper path rollersAre there foreign objects, contamination, or malfunctions onthe paper transport rollers?


ProblemThe printed image is not parallel with the sides of the page.

Initial AnalysisInspect the following components. Are they compatible with your printer ver-sion, correctly installed, not damaged, deformed or contaminated, or free offoreign objects sticking? Toner Cartridge Transfer Roller Assy Fuser Assembly Regist. Roller Assy Feeder Unit Cassette Pickup Roller Paper Cassette Laser/Scanner Assy Mirror Assembly


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P-13 Damaged Prints





Replace the roller.

3333 Paper feedIs the paper fed obliquely?

Go to Skewed Imagetable.

4444 Paper pathAre there obstructions such as burrs or foreign objects, or


ProblemThe printed page is wrinkled, creased, or torn.

Initial AnalysisInspect the following components. Are they compatible with your printer ver-sion, correctly installed, not damaged, deformed or contaminated, or free offoreign objects sticking? Fuser Assembly Fuser Pressure Roller Toner Cartridge Transfer Roller Assy Registration Roller Assy Feeder Unit Cassette Pickup Roller Paper Cassette


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P-14 Unfused Image

Step Actions and Questions Action

(When There Is Problem)




Replace the roller.

3333 Fuser assemblyIs there a proper pressure between the fuser heater rollerand the fuser pressure roller?

Replace the fuser assembly.

4444 Paper pathAre there obstructions such as burrs or foreign objects, orcontamination on the paper path?


ProblemThe printed image is not fully fused to the paper. The image easily rub off.

Initial AnalysisInspect the following components. Are they compatible with your printer ver-sion, correctly installed, not damaged, deformed or contaminated, or free offoreign objects sticking? Fuser Assembly Fuser Pressure Roller DC Controller Board Power Supply Assy


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P-15 No PhotoGrade



1111 RAM Upgrade12 MB of RAM is required to turn on PhotoGrade (20 MB ifusing the duplex feature).Have you installed the necessary RAM?

Install the RAM.

ProblemThe printed image is not printing in PhotoGrade.


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P-16 No Duplex Printing



1111 DriverAre you using the driver version that came with the printer(or later)?

Install the driver.

2222 RAM Upgrade12 MB of RAM is required to use the duplex printing option(20 MB to turn on PhotoGrade). 24 MB is required to doduplex printing with PhotoGrade on legal-size paper.Have you installed the necessary RAM?

Install the RAM.

ProblemYou cannot use the duplex printing option.


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P-17 Duplex Page Upside-Down



1111 DriverAre you choosing the correct binding orientation in thedriver?

Make the correct selections.

2

1

ProblemThe back side of a duplex page is printing upside-down.


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P-18 No Multipurpose Tray Printing


1111 Did you recently take apart and possibly separate the ManualFeed Clutch Gear?

There are two gears on theend of the Manual FeedClutch Gear. DDDDoooo nnnn oooo tttt ssss eeee pppp aaaa ----rrrr aaaa tttt eeee the two gears. Sepa-rating the gears may causea small spring inside thegear to fall off, causing thepickup roller not torotate, resulting in atimeout paper jam. Youcannot see this spring

ProblemPaper feed problems from the multipurpose tray.Other visual/audible symptoms: Click from the manual feed solenoid No rotation of the manual feed roller Pressure plate not rising to create friction against manual feed roller

Service SourceK

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Upgrade


Upgrades RAM Upgrade

RAM Upgrade

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RAM UpgradeThe LaserWriter 12/640 PS comes with 4 MB of RAM, an amount that you can increase uto 64 MB. In addition to font caching and other calculation-oriented factors, increasing RAMis required to enable duplex printing and the PhotoGrade features.

If you want to You need at least

Use the duplex printing option 12 MB memory

Turn on PhotoGrade 12 MB memory

Use the duplex printing option and 20 MB memoryturn on PhotoGrade (24 MB on legal size paper)

The I/O board has two SIMM slots, marked C/D (on the left) and A/B (on the right). Thetable below lists RAM configurations you can use.

Upgrades RAM Upgrade

Total Slot C/D Slot A

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4 MB 0 MB 48 MB 4 MB 48 MB 0 MB 8

12 MB 4 MB 812 MB 8 MB 416 MB 8 MB 816 MB 0 MB 1620 MB 4 MB 16

24 MB 8 MB 1632 MB 16 MB 1632 MB 0 MB 3236 MB 4 MB 3240 MB 8 MB 3248 MB 16 MB 32

48 MB 32 MB 1664 MB 32 MB 32

Slot C/D Slot A/B

I/O Controller Board

Service SourceK

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Take Apar


Take Apart Left Cover - 1

Left Cover

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Left CoverBefore you begin, pull out

the cassette and open the top

cover.

1 Remove the two screws

which fasten the rear

end of the left cover.

2 Shift the cover leftward

to disengage the hidden

hook at the lower right,

raise the cover to clear

the hidden hook on the

top, and pull the cover

from the printer.

Hook 1

Hook 2

Left Cover

Take Apart Multipurpose Cover - 2

Multipurpose

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MultipurposeCover

Before you begin, pull outthe cassette.

1 Open the multipurpose

cover.

2 Disengage the pins at

both sides in the lowerpart of the cover and

open the cover further to

about 90 degrees.

3 Disengage the cover from

the two claws and pull

the cover off the printer.

MultipurposeCover

Claws

Pin

Pin

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Take Apart Top Cover - 4

Top CoverTop Cover

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Top CoverNo preliminary steps are

required before you begin

this procedure.

Note : Peform thisprocedure only if you must

replace the top cover.

1 Pull up the cover releaseand raise the top cover to

about 90 degrees.

2 Using a small flat-blade

screwdriver, release the

two tabs and lift the

cover trim from the

printer. (The cover

ReleaseLever

Tab 1

Top Cover

Tab 2

Tab 1

Cover Trim

Take Apart Top Cover - 5

trim is the 13 x 3.75

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inch plastic piece above

the delivery rollers.)

3 Release the tab thatretains the right hinge

pin and slide the pin out

of the printer. Repeat

for the left hinge pin.

Note : The two door-open springs referenced

below are identical and

interchangeable

4 Remove the two door-

open springs and lift the

top cover from theprinter.

Top Cover

Spring

HingePin

Tab

Take Apart Main Cover - 6

Main Cover

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Main CoverBefore you begin, remove

the following:

Left cover

Multipurpose cover

Multipurpose tray

Note : The main cover is afixed, one-piece housing

that consists of the front,

rear, and right panels.

Seven screws secure the

cover to the chassis.

1 Remove the three screws

on the front side, twoscrews on the top side,

and the two screws on

(1)(2)

Main Cover

Take Apart Main Cover - 7

the rear side that secure the main cover to the chassis.

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2 Flex outward the edge of the cover just below the power

switch and lift the cover straight up from the chassis.

Replacement Note : A slight sideways pull from the I/Oside helps seat the cover assembly.

Take Apart I/O Board - 8

I/O Board

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I/O BoardBefore you begin, remove

the following:

Left cover

Multipurpose cover

Multipurpose tray

Main cover

Note : Perform thisprocedure only if you are

replacing a defective I/O

board. If you are removing

the board to get to a deeper

part, perform the I/O

Shield procedure.

1 Remove the six screws

and remove the I/O board

32

1

4 56

I/O Board

Take Apart I/O Board - 9

(with bracket) from the

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printer.

Note : The I/O boardconnects to the engine

through a receptacle

connector. Remove the

I/O board carefully to

avoid damaging this

connector


near the corner of the

board and the four

screws securing the

connectors to the bracket

and separate the bracket

from the board.

2

1

I/O Bracket

3

4

56

Take Apart I/O Shield - 10

I/O Shield

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I/O ShieldBefore you begin, remove

the following:

Left cover

Multipurpose cover

Multipurpose tray

Main cover


that attach the I/O shieldto the chassis and pull

the I/O shield (with

board in place) from the

printer.

Note : The I/O boardconnects to the enginethrough a receptacle

I/O ShieldLocation of

ReceptacleConnector

Take Apart I/O Shield - 11

connector. Remove the I/O shield carefully to avoid

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damaging this connector

Take Apart DC Controller Board - 12

DC ControllerJ292

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DC ControllerBoard

Before you begin, removethe following:

Left cover

Multipurpose cover

Multipurpose tray

Main cover

I/O shield

1 Remove the screw and

the black cover plate.

2 Remove the screw that

secures the rear edge of

the controller mount tothe chassis. This screw

J292

P/J291

J29

J30J26

J25J24

J23

J22

J28

DC ControllerBoard

Controller Mount

Cover Plate

Take Apart DC Controller Board - 13

is accessible through a rounded notch in the fuser

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assembly.

3 Pull the DC controller board straight out of the printer.

The board mates into a receptacle connector and may

offer some resistance when you begin to pull.

4 Disconnect all connectors on the board.

Perform the step below only if you are replacing a defective

board.

5 Remove the two screws which fasten the DC controller

board to its mount and separate the board from the

mount.

Take Apart Laser/Scanner Assembly - 14

Laser/Scanner

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Laser/ScannerAssembly


Left cover

Multipurpose cover

Multipurpose tray

Main cover

1 Remove the four screws

at the base of the laser/

scanner assembly.

2 Remove the one screw

situated inside the round

recess in top of thelaser/scanner assembly.

J262

J261

Laser/ScannerAssembly

Take Apart Laser/Scanner Assembly - 15

CCCCaaaa uuuu tt tt ii ii oooo nnnn : Do not remove any of the three screws inside

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the square recesses.

3 Lift the laser/scanner assembly, disconnect the two

connectors, and remove the assembly from the printer.

Take Apart Registration Guide Assembly - 16

Registration Guide

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gAssembly


Left cover

Multipurpose cover

Multipurpose tray

Main cover

Laser/scanner assembly

1 Remove the five screws

and remove the assembly

from the printer.


and separate the anglefrom the rest of the

RegistrationGuide Assembly

Take Apart Registration Guide Assembly - 17

registration guide assembly.

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Take Apart Fan Duct - 18

Fan Duct

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Before you begin, remove

the following:

Left cover

Multipurpose cover

Multipurpose tray

Main cover

1 Remove the screw,

release the tab, andremove the duct from the

printer.

Fan Duct

Tab

Take Apart Fan - 19

Fan

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the following:

Left cover

Multipurpose cover

Multipurpose tray

Main cover

Fan duct

1 Disconnect the fan cablefrom connector J222 on

the power supply.

2 Remove the long two

screws and pull the fan

from the chassis.

Fan

J222Note : Connector J221 is empty.

Take Apart Power Supply Assembly - 20

Power SupplyNote : Connector J221 is empty.

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pp yAssembly


Left cover

Multipurpose cover

Multipurpose tray

Main cover

Fan duct DC controller board.

1 Place the printer on its

side so that the fan

points upward.

2 Disconnect the fan cablefrom the edge of the

J222

J11

Power Supply Assembly


power supply.

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3 Disconnect the large white connector next to the power

switch.

4 Remove the seven screws and separate the power supplyassembly from the chassis.

Proceed with steps below only if you are replacing a faulty

power supply board.



hi h h

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which secure the power

supply board to the

plate. (One of them

secures the groundingwire.)


which secure the power

inlet to the plate.

7 Slide the power switchout of its guide and lift

the power supply board

from the plate.

Power SupplyBoard

Take Apart Cartridge Press Actuator - 23

Cartridge Press

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gActuator


Left cover

Multipurpose cover

Multipurpose tray

Main cover

1 Remove the E-ring from

the end of the geared

cam.

2 Working from the inside

of the chassis, slide the

cam from the guide plate.

3 Remove the spring and

Cam

E-Ring

Spring

Guide Plate

Take Apart Cartridge Press Actuator - 24

slide the guide plate down and outward to remove it from

th i t

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the printer.

Take Apart Cover Interlock Actuator - 25

Cover Interlock

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Actuator


Left cover

Multipurpose cover

Multipurpose tray

Main cover

1 Remove the five screws

which secure the actu-

ator assembly to the

chassis.

2 Detach the cam actuator

from the interlockswitch, release the tab,

ActuatorAssembly

Take Apart Cover Interlock Actuator - 26

and remove the cover interlock actuator.

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Take Apart Link Interlock Switch - 27

Link Interlock

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SwitchBefore you begin, remove

the following:

Left cover

Multipurpose cover

Multipurpose tray

Main cover

Cover interlock actuator Power supply assembly

1 Release the latch and pul

out the link interlock

switch.

Link Interlock Switch

Take Apart Mirror Assembly - 28

Mirror Assembly

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the following:

Left cover Multipurpose cover

Multipurpose tray

Main cover

1 Free the cable from the

guide and disconnect theconnector on the under-

side of the assembly.


and lift the mirror

assembly from the

printer.

J301

Cable Guide

Mirror Assembly

Take Apart Drive Transfer Assembly - 29

Drive Transfer

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AssemblyBefore you begin, remove

the following:

Left cover

Multipurpose cover

Multipurpose tray

Main cover

1 Free the cable that runs

across the plate.


and pull off the drive

transfer assembly.

Drive TransferAssembly

Take Apart Main Drive Assembly - 30

Main Drive

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the following:

Left cover

Multipurpose cover

Multipurpose tray

Main cover

DC controller board Drive transfer assembly

1 Remove the four screws

and pull the main drive

assembly from the

chassis.

J25

Main Drive Assembl

Take Apart Transfer Roller Assembly - 31

Transfer RollerTransfer Roller

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the following:

Left cover

Multipurpose cover

Multipurpose tray

Main cover

1 Using a small flatblade

screwdriver, pry each

end of the transfer

roller shaft and remove

the assembly from the

printer.

Replacement Note : Make

Tab

Assembly

Take Apart Transfer Roller Assembly - 32

sure to fully seat the three tabs in the metal guide into the

chassis

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chassis.

Take Apart Registration Roller Assembly - 33

Registration Rolle

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the following:

Left cover

Multipurpose cover

Multipurpose tray

Main cover


and lift out the registra-

tion roller assembly.

Registration RollerAssembly

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Take Apart Delivery Sensor - 35

Delivery Sensor

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the following:

Left cover Multipurpose cover

Multipurpose tray

Main cover


which secure themounting plate to the

chassis.

2 As necessary, disconnect

the cable, release the

tabs, and remove the

photo-interrupter from

the chassis.Mounting Plate Delivery Sensor Cable

Take Apart Delivery Sensor - 36

3 As necessary, remove the actuator(s) and springs(s)

from the mounting plate.

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