Panasonic TC-21FX20P Schematic

Colour Television

TC-21FX20P

GP41 Chassis

ORDER NO. MTV0601423CE

Specifications

Power Source : AC AUTO 110-240V, 50/60 Hz

Power Consumption : 67W Aerial Impedance : 75Ω unbalanced

Coaxial type

Receiving System :

Receiving Channels :

VHF 2-13 (U.S.A. STANDARD)

UHF 14-69 (U.S.A. STANDARD)

CATV 1-125 (U.S.A. STANDARD)

Video / Audio Terminals :

DVD Y 1.0Vp-p, 75Ω PB 0.7Vp-p, 75Ω PR 0.7Vp-p, 75Ω

AV 1,2,3 Video In 1Vp-p, 75Ω Audio In Approx. 0.5V, 47kΩ

Monitor Out Video Out 1Vp-p, 75Ω Audio Out Approx. 0.5V, 1kΩ

Intermediate Frequency :

Video 38.0 MHz

17 Systems

Sound 31.5 MHz (D, K, K1)

32 MHz (I)

32.5 MHz (B, G)

33.5 MHz (M)

Colour 33.57 MHz (PAL)

33.6 MHz (SECAM)

33.75 MHz (SECAM)

34.42 MHz (NTSC)

High Voltage :

Picture Tube : A51LYZ295X

Audio Output : 16.0W

Dimensions : Height:472mm

Mass : 24 kg (Net Wt.)

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

27.5kV ±1.5V

at zero beam current

50.0cm (21 inches)

Measured diagonally,

90° deflection

Width : 648 mm

Depth : 488 mm

TC-21FX20P

CONTENTS

Page Page

1 Safety Precautions 3

1.1. General Guide Lines

1.2. Leakage Current Cold Check

1.3. Leakage Current Hot Check (Fig. 1)

1.4. X-Radiation

1.5. GP41 Chassis Block Diagram

2 Service Hints

2.1. Service Position for E-Board

2.2. Factory Mode Adjustment

2.3. Adjustment for White Balance

2.4. Adjustment for CRT CUT OFF

2.5. Adjustment Procedure

2.6. Adjustment

3 Conductor Views

4 Schematic Diagram

4.1. A Board

4.2. L Board

5 Parts Locations

6 Replacement Parts List

6.1. Replacement Parts List

TC-21FX20P

1 Safety Precautions

1.1. General Guide Lines

1. It is advisable to insert an isolation transformer in the AC supply before servicing this hot chassis.

2. When servicing, observe the original lead dress, especia lly 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, see to it 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 cord outlet.

5. Potential, as high as involves the danger of a shock hazard from 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.

1.2. Leakage Current Cold Check

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

2. Turn on the receiver’s power switch. Measure the resistance value, with an ohmmeter, between the jumper 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 between 4 MΩand 20 MΩ. When the exposed metal does not have a return path to the chassis, the reading must be infinite.

29.0kV

is present when this receiver is in operation. Operation of the receiver without the rear cover

1.3. Leakage Current Hot Check (Fig. 1)

1. Plug the AC cord directly into the AC outlet. Do not use an isolation transformer for this check.

2. Check a 2 kΩnon-inductive resistor and an AC/DC current meter, in series with each exposed metallic part on the receiver in turn and an earth such as a water pipe.

The current from any point should not exceed 0.7 mA peak AC or 2 mA DC. In the case of a measurement being outside of these limits specified, there is a possibility of a shock hazard and the receiver should be repaired and rechecked before it is returned to the customer.

Fig. 1

1.4. X-Radiation

Warning:

The potential sources of X-Radiation in TV set are the EHT section and the picture tube. When using a picture tube test jig for service, ensure that jig is capable of handling

Note:

It is important to use an accurate periodically calibrated high voltage meter.

1. Set the brightness to minimum.

2. Use the remocon to get into Service Mode.

3. Measure the EHT. The meter reading should indicate and correction is required to prevent the possibility of premature component failure.

4. To prevent the possibility X-Radiation, it is essential to use the specified picture tube, if service replacement becomes necessary.

29.0kV

without causing X-Radiation.

27.5±1.5kV

. If the meter indication is out of tolerance, immediate service

TC-21FX20P

1.5. GP41 Chassis 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

AV 3 : 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. Service Position for E-Board

1. Remove the back cover.

2. Stand the TV set as shown in Fig. 2.

3. Remove the A-Board from the TV set by pulling the main board out as shown in Figure 2.

TC-21FX20P

Fig. 2

2.2. Factory Mode Adjustment

1. Factory Mode Adjustment.

a) Set timer ON

b) Press remote’s RECALL (

2. To Set Self-Check:

Press the volume down button on TV then press the Off Timer Button on remote control.

3. Service Mode 1 Controls

4. Service Mode 1 Function

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

5. Service Mode 2 Controls

To enter SERVICE 2; press channel key ‘1’ in SERVICE 1 entry screen.

TC-21FX20P

NOTE :- Service mode 2 options bit.

6. Service Mode 3 Controls

To enter SERVICE 3; press channel key ‘1’ in SERVICE 2 entry screen.

7. Service Mode 3 Function

2.3. Adjustment for White Balance

Preparation:

1. Receive the white balance pattern and aging should have been performed over 30 minutes.

2. Set the picture menu to DYNAMIC NORMAL.

3. Degausse the CRT face.

4. Fix the CRT colour analyze r receiver unit to CRT face.

Adjustment of Low Light.

1. Adjustment Sub Bright, so that Y = 6.5 ± 1.0 nit.

2. Adjustment R-CUT OFF, so that X = 0.245 ± 0.015 nit.

3. Adjustment G-CUT OFF, so that Y = 0.274 ± 0.015 nit.

Adjustment of High Light

1. Adjustment Sub Bright, so that Y = 150 nit.

2. Adjustment R-Drive, so that X = 0.261 ± 0.015 nit.

3. Adjustment B-Drive, so that Y = 0.267 ± 0.015 nit.

TC-21FX20P

2.4. Adjustment for CRT CUT OFF

Preparation:

1. Connect the oscilloscope probe to TPL5.

2. Screen VR min.

3. Set the data Sub Bright, Bright.

4. In service Mode at “Bright” dac press [5] in factory mode to enter vertical line and adjust by volume down or up button.

5. Adjust “Screen VR” until 1-H Line appears.

TC-21FX20P

2.5. Adjustment Procedure

2.5.1. +B Voltage

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 :

TPA 15 : 3.35 ± 0.2V

TPA 16 : 141 ± 2V

TPA 17 : 8.2 ± 0.5V

TPA 18 : 1.9 ± 0.2V

TPA 19 : 5.2 ± 0.2V

TPA 20 : 175 ± 15V

2.5.2. 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 TPA 16 and confirm the +B voltage is 141.0 ± 2V.

2. Connect a high frequency voltmeter to heater and confirm that voltage reads 6.3 ± 0.24 (VRMS).

3. Normalize the brightness and contrast.

2.6. Adjustment

TC-21FX20P

Before Colour Purity, Convergence and White Balance adjustment are attempted,

V. Height, H. Centre and Focus adjustments must be completed.

Colour Purity

1. Set the Brightness and Contrast controls to their maximum positions.

2. Operate the TV set for 60 minutes.

3. Fully degausse the picture tube by using an external degaussing coil.

4. Apply a crosshatch pattern signal and adjust the static convergence magnets to the approximately correct position.

5. Receive a black and white signal.

6. Set the control as follows:

Red................minimum

Green.............minimum

Blue...............minimum

Press the Shipping button on the remote control twice to select CRT Adjustment Mode to select low light.

7. Loosen the clamp screw for the Deflection Yoke A in Fig. 10 and move the Deflection Yoke as close to the purity magnet as possible.

8. Adjust the purity magnetic rings so that a vertical green field is obtained at the centre of the screen.

Convergence

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

2. Adjust Brightness until the grey position of the crosshatch pattern just becomes black.

3. Adjust the Red and Blue line at the centre of the screen by rotating the R-B static.

Fig. 6

9. Slowly push the Deflection Yoke and set it where a uniform green field is obtained.

Fig. 21

10. Re-adjust the Low Light controls to their correct settings and make sure that a uniform white field is obtained.

11. Tighten the clamp screw A in Fig. 10.

Fig. 8

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

5. Lock convergence magnets with silicone sealer.

6. Remove the DY wedges and slightly tilt the Deflection Yoke vertically and horizontally to obtain the good overall convergence.

Fig. 9

7. Fix the Deflection Yoke by reinserting the DY wedges. Refer to Fig. 10.

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

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