Panasonic TX-21FG50A Schematic

ACA

Colour Television

TX-21FG50AAUSTRALIA

GP31 Chassis

ORDER NO. MTV0501369C3

Specifications

Power Source : Power Consumption : 83W Aerial Impedance : 75Ω unbalanced

Receiving System : 17 Systems Receiving Channels :

VHF 1-11 PALB(Australia & N.Zealand)

UHF 21-69 PALGI/SECAMB,G,K1

CATV S1-S41 (Hyper)

Intermediate Frequency:

Video 38.0 MHz Sound 31.5 MHz (D, K, K1)

UTO 110-240V, 50/60 Hz

Coaxial type

1-12 PAL/SECAMD

1-12 NTSC M JAPAN

2-12 PAL/SECAMB,G

2-13 NTSC M U.S.A.

28-69 PALG(Australia)

13-56 PALD

13-52 NTSC M JAPAN

14-69 NTSC NTSC M U.S.A.

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)

ideo/Terminals :

RAV In VideoIn1Vp-p75Ω

udio InApprox. 400mVrms

Monitor Out Video Out 1 Vp-p 75Ω

udio OutApprox. 400mVrms

HighVoltage : 27.5kV±1.5

at zero beam current

Picture Tube :

51cm (21 inches)

Measured diagonally,

udioOutput: 16.0W

Dimensions : Height : 473 mm

Width : 648 mm Depth : 488 mm

Mass : 24 kg (Net W t.)

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

V1, 2

51LXR195

90° deflection

TX-21FG50A-AUSTRALIA

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. GP31 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

3 3 3 3 4

5 5 6 6

2.5. Adjustment Procedure

2.6. PAL Colour

2.7. 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

7 8 8

12 13

15 20

23 24

TX-21FG50A-AUSTRALIA

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, 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, 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 29.0kV is present when this receiver is in operation. Operation of the receiver without the rear cover 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 MΩ and 20 MΩ. When the exposed metal does not have a return path to the chassis, the reading must be infinite.

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 kΩ non-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 29.0kV without causing X-Radiation.

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 27.5±1.5kV. If the meter indication is out of tolerance, immediate service 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.

TX-21FG50A-AUSTRALIA

1.5. GP31 Chassis Block Diagram

CRT

coil

defl.

MONO

STEREO

SOUND MODULATION

3.3V

IC1201

IC1103

EEPROM

Antenna

V OUT

SDA SCL

SAW

TUNER

SIF

SAW

H OUT

CVBS2

AV1

RGB

CVBS3

AV2

IC601

YUV

YUV1

UOC

AUDIO

TRAP

SOUND

IFVO

CVBS1

AMOUT

AMP

IC2301A

CVBSO

QIF / AUDIO

DEEMP

MSP

IC2101

AMP

IC2301

AUDIO

IC3151

AUDIO

SWITCH

OUT

MONITOR

IC851

5V & 8V

IC880

STBY 5V

T801

IC801

LIFE CCT

PRIMARY

SPEAKER

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.

TX-21FG50A-AUSTRALIA

Fig. 2

2.2. Factory Mode Adjustment

How to set : To set the Factory mode, press Volume 0 dac on the TV and Timer Setting 30 min. on

the remote control and press Volume (-) Down button on the TV together press recall on the remote control. CHK should appear on right of TV screen. To move from CHK1 to CHK2 mode, etc. please follow below rotation :

To Set Self-Check : Press the Volume Down button on TV then press the Off Timer button on remote

control.

TX-21FG50A-AUSTRALIA

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 analyzer receiver unit to CRT face.

Adjustment of Low Light.

1. Adjustment Sub Bright, so that Y = 6.3 ± 1.0 nit.

2. Adjustment R-CUT OFF, so that X = 0.235 ± 0.010 nit.

3. Adjustment G-CUT OFF, so that Y = 0.235 ± 0.010 nit.

Adjustment of High Light

1. Adjustment Sub Bright, so that Y = 270 nit.

2. Adjustment R-Drive, so that X = 0.265 ± 0.010 nit.

3. Adjustment B-Drive, so that Y = 0.265 ± 0.010 nit.

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.

2.5. Adjustment Procedure

TX-21FG50A-AUSTRALIA

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 10 : 141.0 ± 1.5V TPA 8 : 8 ± 1V TPA 9 : 5 ± 1V TPA 21 : 175 ± 15V

2.5.2. RF AGC

Item / preparation

1. Receive a colour bar signal at an RF level of 69 ± 1-2 dBU with 75Ω loaded.

2. Connect digital multimeter to RF AGC at Tuner.

Adjustment procedure

1. Select “RF AGC” indication in CHK2, on Screen by remote control at factory mode.

2. Set RF AGC by using remote control Volume (+) or Volume (-) button until voltage AGC at Tuner reaches 2.3 ± 0.1V at TPA 15 (Tuner point).

3. Increase RF signal strength by 2dB, confirm AGC at Tuner voltage drop.

2.5.3. 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 10 and confirm the +B voltage is 141.0 ± 1.5V.

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

3. Normalize the brightness and contrast.

2.5.4. NTSC TINT COLOUR

Item / preparation

1. Connect oscilloscope probe to TPL1 (R OUT) with 10kΩ 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.

TX-21FG50A-AUSTRALIA

2.6. PAL Colour

1. Receive the PAL B/G studio colour bar pattern and adjust local frequency at the best tuned position.

2. Pic Menu: Dynamic Normal, Confirm Contrast - 100 DAC, Sub Contrast - 21 dac.

3. Channel colour set --------- STD

4. “CHK2” and press digit key “5” (AKB OFF) also confirm OSD become blue colour.

5. Set (A) to 2.1 ± 0.1V by BRT (CHK2) at measurement point TPL 2 Fig. 4.

2.7. Adjustment

1. Connect oscilloscope probe to TPL 2 (G OUT) with 10kΩ series resistor and adjust Contrast so that (B) as in Fig. 4 is 2.4 ±

0.05V.

2. Adjust “Sub Colour” so that waveform as in Fig. 4 (1) 2.5 ± 0.1V.

3. Connect oscilloscope probe to TPL 1 (R OUT) with 10kΩ series resistor and confirm waveform as in Fig. 5 is (2) 2.7 ± 0.4V.

4. Press digit key “5” (AKB ON) and confirm the OSD become white colour.

TX-21FG50A-AUSTRALIA

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 forthe 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 sothat avertical green field is obtained at the centre of the screen.

Convergence

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

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 byreinserting the DYwedges. Refer to Fig. 10.

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

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