tv lab mannual

Click here to load reader

Post on 10-Sep-2015

235 views

Category:

Documents

7 download

Embed Size (px)

DESCRIPTION

tv lab manual

TRANSCRIPT

  • R.K.D.F INSTITUTE OF SCIENCE & TECHNOLOGY

    DEPARTMENT OF ELECTRONICS & COMM. ENGG.

    REMOTE CONTROLLED

    COLOUR T.V. TRAINER

    MODEL CDM101

  • b

    PRACTICALS

    Specifications of Colour T.V.

    Safety precautions

    1. To Study the Block Diagram and working principle

    2. To Study Electronic tuner section

    3. To Study Video I.F. Section with circuit diagram

    4. To Study Sound I.F. Section with circuit diagram

    5. To Study Horizontal Oscillator section with circuit diagram

    6. To Study Vertical Oscillator Section with circuit diagram

    7. To Study Colour Picture Tube Section with circuit diagram

    8. To carry out V.I.F. alignment with Sweep Generator

    9. To carry out S.I.F. alignment with Sweep Generator

    10. To measure Video and Audio gain (sensitivity) with Pattern Generator

    11. To demonstrate and understand different types of faults

    12. To study faults diagnosis method

  • 1

    SPECIFICATIONS

    1. System : CCIR-B-PAL-G, 625 lines.

    2. Power supply : 230V + 10% AC, 50 Hz.

    3. Regulation range : 100V AC to 275V AC.

    4. Power consumption : 70 watts max.

    5. R.F. sensitivity : 50 micro / volt

    6. I.F. Frequency Vision : 38.9 Mhz

    Audio : 33.4 Mhz

    7. Sound output : 5.0 watts minimum.

    8. Picture Tube size : 51 cm Diagonal.

    9. Tuner Channels : VHFI- 2 to4, VHF III - 5 to 12,

    BAND IV & V - up to 100

    S-band and Hyper-band.

    10. Program Memory : 90 programs.

    11. RF input impedance : 75 ohms

    12. EHT : 24 KV maximum.

    13. On Screen display for setting of all con trols e.g. Volume, Brightness, Contrast, Colour, Channel and band

    selection, Tuning.

    14. Audio - Video In sockets.

    15. Sections : Operating unit and Tuner, Remote Receiver, Video I.F., Sound I.F., Colour

    decoder, Video amplifier, Horizontal oscillator, Horizontal driver and output,

    S.M.P.S, Vertical , Picture tube, Remote transmitter.

    16. Controls : Volume, Brightness, Contrast, Colour, Channel and band selection, Tuning

    (Hyper and S-Band tuner).

    17. Remote Control functions : Volume, Brightness, Contrast, Colour, Channel selection, Audio mute

    18. Standard Accessories : 1. Trainer Unit

    2. A operating/Service manuals.

  • 2

    SAFETY PRECAUTIONS

    1. Do not touch the EHT transformer, EHT Cable, Screen Cable and Picture Tube earthing.

    2. Do not bring any metal part near to EHT.

    3. Keep alert while measuring Voltages and waveforms of EHT, SMPS transformer and Horizontal deflection

    Coil of Yoke.

    4. Do not touch the PCB with necked feet.

    5. Do not touch 230V AC mains connector and degaussing Coil Connector.

    6. Do not touch AC Fuse, DC Fuse and rectifier section in SMPS.

    7. Do not touch BU208D and BD508A heat sinks and Collector Body.

    8. Do not disturb Yoke convergence assembly.

    9. Do not connect SMPS Ground and Chassis ground.

    10. Measure all Voltage with reference to Chassis ground only unless specified.

    11. Do not alter FOCUS PRESET and SCREEN PRESET o n EHT transformer.

    12. Do not very +115V preset towards high voltage end.

    13. Do not disturb Video coil and AGC preset in VIF section.

    14. Do not very H. Hold preset towards High frequency side.

    15. Isolate SMPS section by removing +115V & +20V jumper whil e creating faults in smps section.

    ******************

  • 3

    To

    23

    0V,

    AC

    Su

    pp

    ly

    (1)

    V1 =

    Ye

    llo

    w c

    on

    nec

    tor

    to Y

    oke Y

    ello

    w w

    ire

    (2)

    V2 =

    Gre

    en

    co

    nn

    ec

    tor

    to Y

    oke G

    ree

    n w

    ire

    (3)

    H1 =

    Red

    co

    nn

    ec

    tor

    to Y

    ok

    e R

    ed

    wir

    e

    (4)

    H2 =

    Blu

    e c

    on

    nec

    tor

    to Y

    oke B

    lue w

    ire

    (5)

    Mu

    lti c

    ore

    w

    ire

    wit

    h C

    RT

    PC

    B &

    So

    cke

    t to

    Pic

    ture

    tu

    be

    (6)

    EH

    T R

    ed

    wir

    e t

    o P

    T E

    HT

    An

    od

    e

    (7)

    2 C

    ore

    LS

    wir

    e t

    o E

    P S

    oc

    ke

    t

    (8)

    1 P

    in E

    art

    hin

    g w

    ire f

    rom

    PT

    to

    CR

    T P

    CB

    1 P

    in C

    on

    nec

    tor

    (9)

    2 P

    in P

    T D

    eg

    au

    ss

    ing

    co

    nn

    ec

    tor

    fro

    m P

    T t

    o S

    MP

    S c

    on

    nec

    tor

    P.S

    Ple

    ase

    no

    te t

    ha

    t D

    eg

    au

    ss

    ing

    co

    nn

    ecto

    r is

    no

    t ap

    plic

    ab

    le in

    B/W

    T.V

    . Tra

    ine

    r

    Co

    nn

    ec

    tor

    Lis

    t

    EH

    T

    V2

    V1

    H1

    H2

    ep

    so

    cket

    2 w

    ire L

    S c

    on

    necto

    r

    Sp

    ea

    ker

    Red

    th

    ick

    wir

    e

    CR

    T p

    cb

    Yo

    ke

    Mu

    lti co

    re

    wir

    e

    Blu

    e w

    ire

    Red

    wir

    e

    EH

    T f

    inal

    An

    od

    e

    Pic

    ture

    fit

    ted

    in

    Ca

    bin

    et

    PT

    eart

    hin

    g w

    ire

    1 p

    in c

    on

    necto

    r

    Yello

    w w

    ire

    Gre

    en

    wir

    eP

    T

    Deg

    au

    ssin

    g

    Co

    ilTw

    o p

    in

    Co

    nn

    ecto

    r

    Co

    nn

    ec

    tio

    n D

    iag

    ram

    fo

    r C

    olo

    ur

    TV

    Tra

    ine

    r

    (1)

    (2)

    (3)

    (4)

    (5)

    (6)

    (7) (8

    )

    (9)

  • 4

    PRACTICAL-1

    BLOCK DIAGRAM AND WORKING PRINCIPLE

    The main functions of a Colour T.V. receiver are as under: -

    1. To select the signals of the channel and to amplify these and convert them into IF Signals.

    2. To amplify the video and sound IF Signals, to demodulate the video IF Signals to obtain the composite

    Video Signal, to mix the two IF signals to obtain the inter - carrier sound IF Signal and to preamplifier

    these.

    3. To separate the combined luminance (Y) and chroma signals from the video IF Signals and to amplify

    these.

    4. To separate the luminance (Y) and chroma i.e. U & V (R -Y and B-Y) Signals from the combined video

    Signal.

    5. To regenerate sub-carrier signal with phase locking with the sub -carrier burst.

    6. To decode the chroma signal to obtain the modulated U and V signals and to demodulate them with the

    Help of regenerated reference carrier.

    7. To combine the Y, U and V signals (Matrixing) to obtain the colour i.e. R, G and B signals.

    8. To amplify them and to give them to the respective cathodes of the colour picture which reproduces these

    As colour picture with the help of horizontal and vertical swee ps.

    9. To produce horizontal and vertical sweeps synchronized with the respective sync signals and to give them

    to the respective deflection coil for producing the sweep.

    10. To separate the sound IF signal, to amplify, limit and demodulate them, and t o give them to the

    Loudspeaker at sufficient amplitude.

    11. To provide power at suitable D.C. voltages for operating various stages, providing supply to various

    Electrodes of picture tube and for heating its cathode.

    12. To provide infrared remote control operations.

    These functions are performed by various stages of the T.V. Receiver, which are explained as under.

    The Block diagram showing different sections is shown in Fig.1.

  • 5

    BLOCK DIAGRAM OF THE COLOUR T.V.

    AN

    TE

    NN

    A

    12

    3

    6A

    6B

    47 5

    8

    9

    SE

    CT

    ION

    NU

    MB

    ER

    S A

    RE

    SH

    OW

    N IN

    TH

    E C

    IRC

    LE

    Figure 1

  • 6

    (1) Tuner: -

    The signal received at the antenna are given to the tuner through the balun. The Tuner, which consists of

    two stages -RF amplifier and converter, partly selects the signal of the desired channel, amplifies it and converts

    it in to I.F. signals.

    The R.F. Amplifier amplifies the signals with the addition of a little n