Panasonic TX-21AD2 Service Manual

Service Manual

Colour Television EURO 2 Chassis

TX-21AD2

Safety

Specifications

Block Diagram(Video)

Block Diagram(Audio)

Block Diagram(Control)

Parts List

Service Information

PCB view(B)

PCB view(E)

Adjustments

Self Check

Service Hints

Mechanical View

Disassembly

Location of Controls

Waveforms

B Schematic

E Schematic

Notes

Service Support

About....

EXITGO BACK

PCB view(Y)

Y Schematic

SM - 96004

Service ManualService Manual

Colour Television

TX-21AD2

EURO-2 Chassis

Specifications

Power Source : 220-240V AC 50Hz

Power Consumption : 80W Aerial Impedance : 75W unbalanced, Coaxial Type Receiving System : PAL I, PAL 60, Receiving Channels : UHF E21 - E69 Intermediate Frequency :

Video 39.5 MHz Sound 33.5 MHz Colour 35.07 MHz

Video / Audio Terminals :

AUDIO MONITOR OUT Audio(RCA x 2) 500mV rms,1kW

AV1 IN Video (21 pin ) 1V p-p 75W

Audio (21 pin ) 500mV rms,10kW RGB (21 pin )

AV1 OUT Video (21 pin ) 1V p-p 75W

Audio (21 pin ) 500mV rms, 1kW

AV2 IN Video (21 pin ) 1V p-p 75W

Audio (21 pin ) 500mV rms,10 kW S-Video IN Y : 1V p-p 75W (21 pin ) C : 0.3V p-p 75W

AV2 OUT Video (21 pin ) 1V p-p 75W

Audio (21 pin ) 500mV rms, 1kW

AV3 IN Audio (RCA x 2)500mV rms,10kW

Video (RCA x 1)1V p-p 75W

High Voltage : 27kV _1kV at zero beam current Picture Tube : 51 cmV measured diagonally.

Audio Output :

Internal Speaker 2 x 20W (Music Power)

8W Impedance

Headphones 8 W Impedance

Accessories supplied : Remote Control

UM3 Battery T.V. Stand

Dimensions : Height : 465mm

Width : 558mm Depth : 495mm

Net Weight 23kg

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

NOTE : This service manual should be used in conjunction

with the EURO 2 technical guide.

Panasonic

Panasonic CS (UK)

WILLOUGHBY ROAD,

BRACKNELL

BERKS,

RG12 8FT.

Contents

Safety Precautions 2 Location of Controls 3 Chassis Service Position 4 Service Mode 5 Self Check 6 Adjustment Procedure 6 Alignment Settings 7 Waveform Pattern Table 8 Block Diagrams 9 P.C.B. Views 12 Schematic Diagrams 14 Parts Location 17 Replacement Parts List 18

Safety Precautions

General Guide Lines

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

2. When servicing, observe the original 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 that all the protective devices such as insulation barriers, insulation papers, shields and isolation R-C combinations are correctly installed.

4. When the receiver is not being used for a long period of time, unplug the power cord from the AC outlet.

5. Potentials as high as 28kV are 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 familiar with the precautions necessary when working on high voltage equipment. Always discharge the anode of the picture to the chassis before handling the tube.

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

Leakage Current Cold Check

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

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 between 4M ohm and 20M ohm. When the exposed metal does not have a return path to the chassis the reading must be infinite.

Leakage Current Hot Check

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

2. Connect a 2k ohm 10W 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 to measure the potential across the resistor.

4. Check each exposed Metallic part and check the voltage at each point.

5. Reverse the AC plug at the outlet and repeat each of the above measurements.

6. The potential at any point should not exceed 1.4 Vrms. In case a measurement is outside the 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.

HOT CHECK CIRCUIT

A.C. Voltmeter

To Instrument's exposed metallic parts

2K ohm 10W

Water Pipe (Earth)

Fig.1

X-Radiation Warning

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

2. When using a picture tube test jig for service ensure that the jig is capable of handling 28kV without causing X-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 should indicate 27kV _1kV at zero beam current if the meter indication is out of tolerance, immediate service and correction is required to prevent the possibility of premature component failure.

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

Location Of Controls

FOCUS

Fig.2

Service Hints

How to remove the rear cover

i. Remove the 5 fixing screws (A) as shown in Fig.3/Fig.4.

SCREEN

SCREW

Fig.4

SCREWS (A)

Fig.3.

How to move the chassis into the Service position

NOTE: To place the chassis into the advised service position the T.V. must be on the T.V. stand provided with the set.

1. To place the chassis into service position hold and lift the rear of the E-PCB chassis and gently pull the chassis toward you as shown in Fig.5.

B-PCB service position.

i. Release the respective wiring clips and rotate the chassis horizontally through 90_ anti-clockwise, then lift the front of the chassis as shown in

Fig.6. ii. Insert the bead clamper located in the bottom left hand corner of the cabinet (Fig.8.) into the chassis frame shown in Fig.9. iii. After servicing ensure all wiring is returned to its original position before returning the receiver to the customer.

E-PCB service position.

i. Release the respective wiring clips and rotate the chassis horizontally through 180_ anti-clockwise, the lift the FBT side of the chassis as shown

in Fig.7. ii. Insert the bead clamper located in the bottom left hand corner of the cabinet (Fig.8.) into the chassis frame shown in Fig.9 iii. After servicing ensure all wiring is returned to its original position before returning the receiver to the customer.

Fig.5

CABINET

E - PCB

B - PCB

T.V. STAND

Fig.6.

BEAD

CLAMPER

CHASSIS

FRAME

E - PCB

Fig.8.

MAINS

SWITCH

INSERT

BEAD

CLAMPER

B - PCB

T.V. STAND

Fig.7.

Fig.9.

TX-21AD2

Service Mode

The remote control is used for entering and storing adjustments, with the exception of cut-off adjustments which must always be done prior to service adjustment. Perform adjustments in accordance with screen display. The display on the screen also specifies the CCU variants as well as the approx. setting values. The adjustment sequence for the service mode is indicated below.

1. Set the Bass to maximum position, set the Treble to minimum position, press the F button followed by the Volume down on the customer controls at the front of the TV and at the same time press the Reveal button on the remote control, this will place the TV into the Service Mode.

2. Press the RED / GREEN buttons to step down / up through the functions.

NOTE: This TV also has the option of using a Memory Pack which enables you to copy the preset TV channels and analogue levels into the Memory

Pack and then upload them onto another EURO-2 TV set.

3. Press the YELLOW / BLUE buttons to alter the function values.

4. Press the STORE button on the preset panel after each adjustment has been made to store the required values.

5. To exit the Service Mode press the Normalisation button.

Using the Memory Pack

TV to Memory Pack process

1. Plug the memory pack into the lower of the two 21 pin terminals at the back of the TV and switch the TV on. If the TV has only one 21 pin connector then this will be able to accept the memory pack.

2. Go into the Service Mode as explained above. The screen will show:-

Program

External>>TV

Program

TV>>External

3. Press the blue button on the remote control. The screen will show:-

4. Press the STORE button on the TV. The screen will show:-

Storing

2. Go into the Service Mode as explained above. The screen will show:-

Program

External>>TV

4. All the tuning information stored inside the Memory Pack will now be transferred to the TV. This process will take 2-3 minutes to complete and when finished the screen will show:-

3. Press the STORE button on the TV. The screen will show:-

5. All the tuning information stored inside the TV will now be transferred to the Memory Pack. This process will take 2-3 minutes to complete and when finished the screen will show:-

OK!

Memory Pack to TV Process

5. The tuning information from the Memory Pack has now been copied into the TV

6. To exit from the Service Mode switch off the TV.

7. The process has now been completed and the Memory Pack can now be removed.

OK!

Errors

If an error occurs while using the Memory Pack the TV will detect this and the screen will show:-

Program Error!

If this happens then switch off the TV and repeat the process that was being used. If the errors continue to occur then check the connectors between the TV and the memory pack and check the 9V battery inside the memory pack.

TX-21AD2

VIF

Video AV

Dolby IC

MSP

P SBLED

P OFF

P RAM

SELF CHECK

Self check is used to automatically check the Bus lines and Hexadecimal code of the TV set. To enter the Self Check mode press Function down button, on the Preset Panel, at the same time pressing the Status button, on the Remote Control, and the screen will show:-

Tuner

1 2 3 4 5 6 7 8 9

ok ok

EEPROM

Sound AV

- -

switch1

switch1 VDP

TPU

ok ok

- -

Dolby Sub

- -

for L/R

11 12 13 14 15 16 17 18 19 20

If the CCU ports have been checked and found to be incorrect then "--" will appear in place of "OK".

- -

for C/R

P S MODE

P. TA0

P. TA1

ok ok

P. TA2

P. TA3

P SDA

ok ok

P SCL 3

P SCL4

21 22

23 24

ok ok

Hex codes

06 CE

34 94

P DEFL

Adjustment Procedure

Item/Preparation Adjustments

+B SET-UP

1. Receive a window pattern

2. Set the controls: Brightness minimum Contrast minimum Volume minimum

RF AGC

1. Receive a test pattern.

2. Connect an oscilloscope between the tuner RF AGC and ground.

3. Set the oscilloscope gain range to 1V/div.

CUT OFF

1. Receive a window pattern.

2. Degauss the tube externally.

3. Set the TV into Service Mode 1.

4. Select Cutoff DC mode.

1. Set the +B voltage up as follows: Adjust R811 so that B2 shows 130V +/- 1V

2. Confirm the following voltages.

B1 200 +/- 10V B6 12 +/- 0.5V B3 27 +/- 1V B7 5 + 0.1/-0.25V B4 41.0 +/- 1V B8 5 +/- 0.25V B5 15.5 +/- 1V U33 31 +/- 1V

1. Check that the noise becomes large when the RF AGC VR

R126 is turned counterclockwise. After the check turn it clockwise.

2. Gradually turn the RF AGC VR anti-clockwise, and set the RF AGC VR to the point where the RF AGC voltage is just falling to a point where this voltage drops by 0.2V from the maximum value.

1. Confirm then value is 128 and select Ug2 mode noting colour with largest value

2. Turn the screen VR until a colour reaches 20~30.

3. Connect an oscilloscope to the cathode with the biggest value

colour.

4. Select Cutoff DC mode and adjust Cutoff pulse to 159V +/- 5V.

5. Disconnect the oscilloscope and adjust the screen to whichever colour reaches 70 +/- 30 first.

TX-21AD2

Alignment Settings (The figures used below are nominal and used for representative purposes only)

Alignment Function TX-21AD2 Settings / Special features

1. Vertical amplitude V-AMP 063

2. Vertical symmetry V-SYM 002

3. Vertical linearity V-LIN

-020

4. Vert. D.C. Vert. D.C. 000

5. V-Pos. V. Pos 005

6. Horizontal amplitude H-AMP

-044

7. Horizontal position H-POS 542

8. Text Position TEXT POSITION 049

9. EW-amplitude E-W AMP 1

-059

10. EW-amplitude E-W AMP 2 044

Optimum setting

No Adjustment

Optimum setting

11. Trapezium-comp TRAPEZ 1 000

12. Trapezium- comp TRAPEZ 2

-009

13. Colour VCO Colour VCO 006

14. Cut-off DC Cut-off DC 050

Ug 2 Test

15. Ug2 Test

16. Cutoff Cutoff

17. White White

094 044 020

057 064 056

200 255 246

Optimum setting

Press either Blue or Yellow buttons to effect automatic adjustment

No Adjustment

Select Cutoff DC in Service Mode mode and confirm the value is 128. Select Ug 2 Test noting colour with largest value, adjust on FBT until a colour reaches 20 ~ 30. Connect an oscilloscope to the cathode of the biggest value colour, select Cutoff DC mode and adjust get Cutoff pulse voltage to 159_5V. Disconnect the oscilloscope and adjust the screen to whichever colour reaches 70_30 first.

Press the GREEN button to step through the settings. Adjust for optimum.

PIN 42

10u

PIN 6 E8

50u sec/div

PIN 5 E8

10u

PIN 3 E8

10u

PIN 4 E8 10u

PIN 6

5m sec/div

COLLECTOR

64u sec/div

PIN 44 10u (Chroma)

PIN 3

5u sec/div

BASE Q503

20u sec/div

PIN 7

2u sec/div

PIN 6

5m sec/div

PIN 7 5m sec/div

PIN 18 5u sec/div

PIN 34

5m sec/div

BASE 20u sec/div

PIN 8

64u sec/div

RED DRIVE

EMITTER

80v

PIN 1

5m sec/div

GREEN DRIVE

EMITTER Q352

100v

PIN 5

5m sec/div

BLUE DRIVE

EMITTER Q353

120v

+ 19 hidden pages