Panasonic TX-21JT3P Schematic

ORDER No. SM-04019

Service Manual

Colour Television

Z-M3L Chassis

TX-21JT3P

SPECIFICATIONS

Power Source: 220 - 240V A.C., 50Hz Video/Audio Terminals:

Power Consumption: 60W AV1 IN Video (21 pin) 1V p-p 75Ω

Audio (21 pin) 500mV rms 10KΩ

Stand-by Power Consumption: 1W RGB (21 pin)

Audio (RCA x 1) 500mV rms 10KΩ Video (RCA x 1) 1V p-p 75Ω

Receiving System: PAL B/G, D/K, 525/60

SECAM B/G, D/K AV1 OUT Video (21 pin) 1V p-p 75Ω M.NTSC Audio (21 pin) 500mV rms 10K NTSC (AV only)

Receiving Channels: VHF E2-E12 VHF H1-H2 (ITALY) Picture Tube: A51LZM10X16N45 51cm

VHF A-H (ITALY) VHF R1-R2 VHF R3-R5 VHF R6-R12 High Voltage: 29 ± 1kV UHF E21-E68 CATV (S01-S05) CATV S1-S10 (M1-M10) CATV S11-S20 (U1-U10) Audio Output: 20W CATV S21-S41 (HYPERBAND) (Music Power) 8Ω

Headphones: 8Ω Impedance

Intermediate Frequency: Video 38.9MHz, 34MHz 3.5mm Video/Audio

Audio 32.9MHz, 33.16MHz, 33.4MHz Accessories: Remote Control

2 x R6 (UM3) Batteries

Colour 34.47MHz (PAL)

34.5MHz, 34.65MHz (SECAM) Dimensions: Height: 482 mm Width: 506 mm Depth: 484 mm

Ω

Net Weight: 20kg

NOTE:

Specifications are subject to change witho ut notic e. Weights and dimensions shown are approx imate .

CONTENTS

SAFETY PRECAUTIONS.........................................................................................................................................................2

SERVICE HINTS.......................................................................................................................................................................3

ALIGNMENT PROCEDURE.....................................................................................................................................................4

WAVEFORMS...........................................................................................................................................................................5

BLOCK DIAGRAM....................................................................................................................................................................7

PARTS LOCATION...................................................................................................................................................................8

REPLACEMENT PARTS LIST..................................................................................................................................................9

SCHEMATIC DIAGRAMS.......................................................................................................................................................13

PCB CONDUCTOR VIEWS....................................................................................................................................................18

SAFETY PRECAUTIONS GENERAL GUIDE LINES

1. It is advisable to insert an isolation transformer in the a.c. 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 that have been overheated or damaged by the short circuit.

3. After servicing, see that all the protective devic es 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 a.c. outlet.

5. Potentials as high as 30kV 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 tube.

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

LEAKAGE CURRENT COLD CHECK

1. Unplug the a.c. 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 a.c. 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 a.c. cord directly into the a.c. outlet. Do not use an isolation transformer for this check.

2. Connect a 2kΩ 10W resistor in series with an exposed metallic part on the receiver and an earth, such as a water pipe.

3. Use an a.c. 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 a.c. plug at the outlet and repeat each of the above measurements.

6. The potential at any point should not exceed 1,4Vrms. 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

ΩΩΩΩ

10 Watts

TO INSTRUMENT'S EXPOSED METALLIC PARTS

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 30kV 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. 29kV ± 1kV. 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 any X-Radiation possibility, it is essential to use the specified tube.

WATER PIPE

(

EARTH)

SERVICE HINTS

How to remove the rear cover

1. Remove the 5 screws as shown in Fig.2.

SCREWS

LOCATION OF CONTROLS

SCREWS

Fig. 2.

AV Board

Main Board

CRT Board

Focus

Screen

ALIGNMENT PROCEDURE AND OPTION SETTING

Self Check Mode

To enter self check mode, set the programme position to Channel 99. Set sharpness to a minimum, press the status button ( ) on the remote contol whilst simultaneously pressing the down button ( ) at the front of the set. This should bring the set into self check mode.

Entering SERVICE mode

Whilst in self check mode, press the mute remote key ( ) and local down button on the set ( ) simultaneously. The user must make sure that Sharpness is set to a minimum and that the programme position is set to Channel 99 as well. This should bring the user to service mode1. Scroll through the service items using the cursor up and down keys and adjust accordingly using the - /+ keys on the r emote.

Service mode navigation

Up /Down remote keys :scroll through the service items available.

-/+ remote keys :Decrement/Increment the values within range. TV/AV :Store the current data.

ORDER FUNCTIONS AND SETTINGS VALUES (NOMINAL VALUES)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Cut Off Alignment UG2 Vertical Slope V-Slo Vertical Positio n V-Pos Vertical Amplitud e V-Amp Horizontal Position H-Ctr Horizontal Parabola H-Par Horizontal Bow H-Bow Red Colour Cut R-Cut Green Colour Cut G-Cut Red Colour Drive R-Drv Green Colour Drive G-Drv Blue Colour Drive B-Drv RF Automatic Gain Control AGC Sub Colour S-Col Sub Brightness S-Bri East/West Width (Horizontal Amplitude) EW-WD East/West Parabola EW-PR East/West Upper Corner EW-UC East/West Lower Corner EW-LC East/West Trapezium EW-TP

TEST 033 005 045 039 030 021 037 031 063 048 038 035 011 040 017 039 044 042 034

Cut Off UG2 alignment: Adjust it on AV mode.

Set condition is in AV mode without signal. Place the set into an Ageing Test for more than 15 minutes. Adjust the unit to the following settings. R-Cut=32, G-Cut=32, R-Drv=42, G-Drv=42, B-Drv=42. Press the G2 button on the service remote. Adjust the Screen Volum e on the FBT until the indicator on the set will be lit.

White Balance: Adjust this after performing CUT OFF UG2 alignment.

Place the set into an ageing test for approximately 15 minutes. Generate a gray scale pattern from a Pattern Generator. Set the colour balance to normal position. Press the FACTORY button on the service remote. Adjust accordingly using +/- button on the service remote to whiten the settings of R-Cut, G-Cut, R-Drv and G-Drv at each section equally.B-Drv step number however should be fixed at 42.

MICON/CHROMA

WAVEFORMS

20µs 1V

5ms

0.5V

6 17

20µs 1V

20µs 2V

5ms 10V

20µs 5V

20µs 1V

20µs 2V

DEFLECTION/CRT

5ms

0.5V

20µs

0.5V

20µs 50V

The following waveforms were measured at the point of the corresponding

NOTE:

balloon number in the schematic diagram.

H-1

20µs 50V

WAVEFORMS

SOUND AMP/21PIN

1ms 200mV

1ms

0.5V

The following waveforms were measured at the point of the corresponding

NOTE:

balloon number in the schematic diagram.

H-2

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