Panasonic TC-21FG20P Schematic

ORDER NO. MTV0501396C3

Colour Television

TC-21FG20P

GP31 Chassis

Specifications

Power Source :	AC AUTO 110-240V, 50/60 Hz	Video / Terminals :	AV1, 2
Power Consumption :	83W	RAV In	Video In 1 Vp-p 75Ω
Aerial Impedance :	75Ω unbalanced		Audio In Approx. 400mVrms
	Coaxial type	Monitor Out	Video Out 1 Vp-p 75Ω
Receiving Channels :			Audio Out Approx. 400mVrms
VHF	2-13 (USA STANDARD)	High Voltage :	27.5kV±1.5
CATV	1-125 (USA STANDARD)		at zero beam current
UHF	14-69 (USA STANDARD)	Picture Tube :	A51LXR195X
Intermediate Frequency :			51cm (21 inches)
Video	38.0 MHz		Measured diagonally,
Sound	31.5 MHz (D, K, K1)		90° deflection
	32 MHz (I)	Audio Output :	16.0W
	32.5 MHz (B, G)	Dimensions :	Height : 473 mm
	33.5 MHz (M)		Width : 648 mm
			Depth : 488 mm

Colour	33.57 MHz (PAL)
	33.6	MHz (SECAM)
	33.75	MHz (SECAM)
	34.42 MHz (NTSC)

Mass :

24 kg (Net Wt.)

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

© 2005 Matsushita Electric Industrial Co., Ltd. All rights reserved. Unauthorized copying and distribution is a violation of law.

CONTENTS

	Page			Page
1 Safety Precautions	3		2.5. Adjustment Procedure	7
1.1. General Guide Lines	3		2.6. PAL Colour	8
1.2. Leakage Current Cold Check	3		2.7. Adjustment	8
1.3. Leakage Current Hot Check (Fig. 1)	3	3	Conductor Views	12
1.4. X-Radiation	3	4	Schematic Diagram	13
1.5. GP31 Chassis Block Diagram	4		4.1. A Board	15
2 Service Hints	5		4.2. L Board	20
2.1. Service Position for E-Board	5	5	Parts Locations	23
2.2. Factory Mode Adjustment	5	6	Replacement Parts List	24
2.3. Adjustment for White Balance	6		6.1. Replacement Parts List	25
2.4. Adjustment for CRT CUT OFF	6

2

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.

3

				EEPROM
				IC1103
	Antenna
				SDA	SCL
	TUNER	SAW	IF			V	V OUT
		SAW	SIF
						H	H OUT
	AV1		CVBS2
	AV2		CVBS3			R
						G
	YUV1		YUV	IC601		B
				UOC
	AUDIO					IFVO	SOUND
SPEAKER	AMP		AMOUT
						CVBS1	TRAP
	IC2301A
4	AUDIO					CVBSO
		MSP
	AMP		QIF / AUDIO
		IC2101
	IC2301		DEEMP
				SW
	MONITOR	AUDIO
		SWITCH
	OUT
		IC3151
				IC851
				5V & 8V
		PRIMARY		IC801			IC880
		LIFE CCT		T801			STBY 5V

R
defl.
G	CRT
coil
B

SOUND MODULATION MONO STEREO

IC1201

3.3V

Diagram Block Chassis GP31 .5.1

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.

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.

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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.

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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 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.

7

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.

8

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 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 by reinserting the DY wedges. Refer to Fig. 10.

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

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