Panasonic CT-F2156WLP Service Manual

Colour Television

CT-F2156WLP

GP41 Chassis

Order No. MTV0601454CE

Specification

Power Source AC SINGLE 220 V, 50/60 Hz Power Consumption 67 W

Standby condition : 2 W Aerial Terminal Impedance : 75Ω, Coaxial type Tuning System

Receiving System MTS STEREO Receiving Channels Regular TV VHF BAND 2-13 (NTSC M U.S.A) UHF BAND 14-69 (NTSC M U.S.A.) CATV 1-125 (U.S.A. CATV) Intermediate Frequency 38.0 MHz Video 31.5 MHz (D, K) / 32.5 MHz (B, G)

Sound 33.57 MHz (PAL) / Colour 33.6 MHz (SECAM)

Video/Audio/Terminals DVD

Frequency Synthesizer

Auto Search Tuning

Pos : 100 Positions

32.0 MHz (I) / 32.5 MHz (M)

34.42 MHz (NTSC) /

33.75 MHz (SECAM)

Y 1.0 Vp-p, 75Ω P

AV 1, 2, 3 Video in 1.0 Vp-p, 75Ω Audio in Approx. 0.5V , 47KΩ Audio Amp AUDIO L-R 0.5V RMS

(PHONE JACK TYPE x 2)

High Voltage 27.5 ±1.5 at zero

Picture Tube A51LYZ295X Type 21 (500 mm)

Audio Output 16 W speaker Dimensions (W x D x H) 648 mm x 472 mm x 488 mm Weight (Mass) 24.5 kg (Net)

Note:

Specifications are subject to change without notice. Mass and dimensions shown are approximate.

0.7 Vp-p, 75Ω

beam current

Measured diagonally,

104° defl ect ion

CT-F2156WLP

CONTENTS

Page Page

1 Safety Precautions 3

1.1. General Guide

1.2. Leakage Current Cold Check

1.3. Leakage Current Hot Check (See Fig. 1)

1.4. X-Radiation

1.5. GP41 Block Diagram

2 Service Hints

2.1. HOW TO MOVE CHASSIS INTO SERVICE POSITION.

3 Market Mode Function

3.1. Service Mode Access

3.2. Service Mode 1 Controls

3.3. Service Mode 1 Function

3.4. Service Mode 2 Controls (OPTION data 1 ~ 3)

4 Adjustment Procedure

4.1. Adjustment Procedure

3 3 3 3 4

6 6 6 6

4.2. COLOUR PURITY

4.3. CONVERGENCE

4.4. WHITE BALANCE (MARKET MODE CHK 4)

4.5. ADJUSTMENT OF CRT VRS

5 Conductor Views 6 Schematic Diagrams

6.1. SCHEMATIC DIAGRAM FOR GP41 CHASSIS

6.2. A Board

6.3. L Board

6.4. G Board

7 Parts Locations 8 Replacement Parts List

8.1. Replacement Parts List Notes

8.2. Replacement Parts List

7 8 9

11 12

12 14 19 22

25 26

26 27

CT-F2156WLP

1 Safety Precautions

1.1. General Guide

1. It is advisable to insert an isolation transformer in the AC

supply before servicing a hot chassis. Fig. 1.

Fig. 1

2. When servicing, observe the original lead dress, especially

the lead dress in the high voltage circuits. If a short circuit is found, replace all parts which have been overheated or damaged by the short circuit.

3. After servicing, observe that all the protective devices such

as insulation barriers, insulation papers, shields, and isolation R-C combinations, are properly installed.

4. When the receiver is not to be used for a long period of

time, unplug the power cord from the AC outlet.

5. Potential, as high as

is in operation. Operation of the receiver without the receiver power supply. Servicing should not be attempted by anyone who is not thoroughly familiar with the precautions necessary when working on high voltage equipment. Always discharge the anode of the picture tube to the receiver chassis before handling the tube.

After servicing make the following leakage current checks to prevent the customer from being exposed to shock hazards.

29kV

kV is present when this receiver

1.3. Leakage Current Hot Check (See Fig. 1)

1. Plug the AC cord directly into the AC outlet. Do not use an

isolation transformer for this check.

2. Connect a 2 kΩ, 10 W resistor in series with an exposed

metallic part on the receiver and an earth such as a water pipe.

3. Use an AC voltmeter, with high impedance type, to

measure the potential across the resistor.

4. Check each exposed metallic part, and measure the

voltage at each point. Fig. 3.

Fig. 3

5. Reverse the ACplug in the AC outlet and repeat each of the

above measurements.

6. The potential any point should not exceed

case of a measurement being outside of the limits specified, there is a possibility of a shock hazard, and the receiver should be repaired and re-checked before it is returned to the customer. Fig. 4.

1.0 V rms

. In the

1.2. Leakage Current Cold Check

1. Unplug the AC cord and connect a jumper between the two prongs on the plug. Fig. 2.

Fig. 2

2. Turn on the receiver’s power switch.

3. Measure the resistance value, with an ohmmeter, between the jumpered AC plug and each exposed metallic cabinet part on the receiver, such as screw heads, aerials, connectors, control shafts, etc. When the exposed metallic part has a return path to the chassis, the reading should be

ΩΩΩΩ

between not have a return path to the chassis, the reading must be zero.

and 20 M

ΩΩΩΩ

. When the exposed metal does

Fig. 4

1.4. X-Radiation

Warning :

1. The potential sources of X-Radiation in TV sets are the EHT section and the picture tube.

2. When using a picture tube test rig for service, ensure that the rig is capable of handling Radiation.

Note:

It is important to use an accurate periodically calibrated

high voltage meter.

1. Set the brightness to minimum.

2. Measure the High Voltage. The meter reading should indicate tolerance, immediate service and correction is required to prevent the possibility of premature component failure.

3. To prevent the possibility of X-Radiation, it is essential to use the specified picture tube.

27.5 ± 1.5V

. If the meter indication is out of

29 kV

without causing X-

CT-F2156WLP

1.5. GP41 Block Diagram

CRT

coil

defl.

29" models

CRT

DRIVE

VM DRIVE

PIP models

IC1101

EEPROM

RGB

SCL SDA

SCL

SDA

R/G/B

PVP

IC1801

CVBS

GP41 CHASSIS BLOCK DIAGRAM

SPEAKER

R/G/B

CVBS OUT

AMP

AUDIO

VCT-IF

OUT

AUDIO

IC2301

REAR INPUTS

IC601

MON_OUT

AV1 : V/L/R

AV3 : YUV/V/L/R

V OUT

TUNER

AV2 : V/L/R

FRONT INPUTS

MON_OUT

H OUT

V/L/R

MAIN

POWER

SWITCH

AV2 : V/L/R

FRONT INPUTS

GEOMAGNETIC

AMP

IC2401

WOOFER

2 Service Hints

2.1. HOW TO MOVE CHASSIS INTO SERVICE POSITION.

1. Remove 9 screws.

CT-F2156WLP

2. Draw out Main Chassis.

3. Stand the Main Chassis.

CT-F2156WLP

3 Market Mode Function

3.1. Service Mode Access

1. Set timer ON.

2. Press remote’s RECALL (

3. Set to normal mode : Press the volume down button on front, together press the off timer button on remote control.

3.2. Service Mode 1 Controls

) and panel’s volume down key simultaneously to enter SERVICE 1.

1. Key 3 / 4 previous / next service 1 item

2. Key 8 / 9 adjust user brightness (-/+)

3. Program up / down program position up / down

4. Volume + increment of selected item

3.3. Service Mode 1 Function

1. H-POS

-128~127

2. V-POS

-128~127

3. H-AMP

-128~127

4. V-AMP

-128~127

5. EW-AMP1

-128~127

6. LOW_Corner

-128~127

7. TRAPEZ 1

-128~127

8. UPPER_Corner

-128~127

9. V-LIN

-128~127

10. V-SYM

-128~127

5. Volume decrement of selected item

6. OK (remote) store / save selected item

7. Normal (remote) exit service mode

11. ANGEL

-128~127

12. BOW

-128~127

13. DVCO

-128~127

14. H-POS

-128~127

15. G-CUT OFF N/A

16. B-CUT OFF 0~511

17. R-DRIVE 0~511

18. G-DRIVE 0~511

19. B-DRIVE 0~511

20. SUB-Bright

-128~127

3.4. Service Mode 2 Controls (OPTION data 1 ~ 3)

1. Key 3 / 4 previous / next service 2 item

2. Key 8 / 9 toggle for options bit 0 - 7

3. Program up / down program position up / down

4. Volume + increment of selected item

5. Volume decrement of selected item

6. OK (remote) store / save selected item

7. Normal (remote) exit service mode

NOTE: Service mode 2 options bit refer to each model spec.

4 Adjustment Procedure

4.1. Adjustment Procedure

4.1.1. +B Voltage

CT-F2156WLP

Item / preparation

1. Operate the TV set.

2. Set control as follows :

Brightness ........... minimum

Contrast ............... minimum

Adjustment procedure

1. Confirm the DC voltage at the indicated test points, as follows :

TPD 15 : 3.35 ± 0.2V TPD 16 : 141 ± 2V TPD 17 : 8.2 ± 0.5V TPD 18 : 1.9 ± 0.2V TPD 19 : 5.2 ± 0.2V TPD 20 : 175 ± 15V

4.1.2. High Voltage

Item / preparation

1. Receive the crosshatch pattern.

2. Set to 0 Beam.

Screen VR .......... minimum

Contrast .............. minimum

Adjustment procedure

1. Connect a DC voltage meter to D866 and confirm the +B voltage is 141.0 ± 2V.

2. Connect a high frequency voltmeter to heater and confirm that voltage reads 6.30 ± 0.24 (VRMS).

3. Normalize the brightness and contrast.

4.1.3. NTSC TINT COLOUR

Item / preparation

1. Connect oscilloscope probe to TPL1 (R OUT) with 10k series resistor.

2. Press Main Menu and set system to use AV-NTSC (3.58 MHz).

DYNAMIC ................... Normal

Channel CLR Set ..... STD

Adjustment procedure

1. Adjust Sub-Tint so that No. 2, 3 and 4 becomes level waveform is similar to Fig. 3.

2. Confirm phase at Tint is changes more than ± 15 by Tint control.

3. Confirm that colour level is maximum when colour DAC is adjusted to maximum position.

Note:

Use remote control only when adjusting user mode to

Sub-Tint.

Ω

4.2. COLOUR PURITY

1. Set Bright and Contrast controls to their maximum positions.

2. Operate the TV set over 60 minutes.

3. Full degauss the picture tube by using an external degaussing coil. By rotating R-B static convergence magnet.

4. Apply a crosshatch pattern signal and adjust roughly the static convergence magnets.

5. Apply a green pattern signal.

6. Loosen a clamp screw for the Deflection Yoke and move the Deflection Yoke as close to the purity magnet as possible.

7. Adjust the purity magnet so that a vertical green field is obtained at the center of the screen.

8. Slowly press the Deflection Yoke and set it where a uniform green field is obtained.

9. Adjust roughly the Low Light controls and make sure that a uniform white field is obtained.

10. Tighten the clamp screw.

CT-F2156WLP

4.3. CONVERGENCE

1. Apply a crosshatch pattern signal and set Contrast control to the maximum position.

2. Adjust Bright control to obtain a clear pattern.

3. Adjust Red and Blue line at center of the screen.

4. Adjust Red and Blue with Green line at center of the screen by rotating (RB)-G static convergence magnet.

5. Lock convergence magnets with silicone sealer.

6. Remove the DY wedges and slightly tilt the Deflection Yoke vertically.

7. Fix the Deflection Yoke by re-inserting the DY wedges.

8. If purity error is found, repeat “Colour Purity” adjustment.

4.4. WHITE BALANCE (MARKET MODE CHK 4)

Preparation

1. Receive a colour bar signal with colour “OFF”, and operate the TV set for more than 30 minutes.

2. Set the picture menu to “DYNAMIC NORMAL” and the AI to off.

3. Connect an oscilloscope to KG on L BOARD.

4. Set the TV set to Market Mode : white balance adjustment (CHK 4).

5. Screen VR : Min.

6. Set the data level of RGB CUT OFF / DRIVE and SUB BRIGHT.

Adjustment

1. Select G-CUTOFF adjustment mode and collapse vertical scan.

2. Adjust G-CUTOFF control to become the DC=0 V to video level at 150 V as shown in Fig. 1.

8. Wedge A shown in Fig. 2 should be fixed within a range of 45° to the left of the vertical line as shown.

9. After inserting wedge A, insert wedges B, C and D. The wedges should be set 90° apart from each other.

10. Be certain that the four wedges are firmly fixed and the Deflection Yoke is tightly clamped in place otherwise the Deflection Yoke may shift its position and cause a loss of convergence and purity.

CT-F2156WLP

Fig. 1

3. Slowly turn the screen control clockwise until a green colour horizontal line appears on the picture tube. This is the setting point for the screen control. Note:

Do not adjust the G-CUTOFF setting in the following procedure.

4. Adjust the remaining R and B-CUTOFF controls so as to get a white horizontal line on the screen.

5. Return to full field SCAN by pushing the position 5 key on the remote control.

6. Adjust the R-Drive and B-Drive controls as to obtain a uniform white on the white bar of the greyscale pattern.

7. Confirm correct B/W rendition and greyscale tracking or repeat CUTOFF and drive control setup.

Note:

Write down the original value for each address adjustment before adjusting anything.

CT-F2156WLP

4.5. ADJUSTMENT OF CRT VRS

PREPARATION

1. Set DY to CRT not to tilt up and down left and right deflection. (fig 1)

2. Set CY to CRT and set CY magnet primarily. Pur Mg : Set Pur Mg that 2magnets are top position. VRS Mag : Set VRS Mg that 2magnets are horizontal position.

ADJUSTMENT

1. Receive the white balance pattern.

2. Adjust V-CENTER.

3. Set R,B CUT OFF to minimum, and set G CUT OFF to center.

4. Receive the aging pattern.

5. Set 2 magnet of vertical position to up and down equally so that center part of CRT (Fig. 2)

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