panasonic TC-20LB30 Service Manual

Specifications

ORDER NO. ITD0406015C1

B05 Canada:B07

LCD TV

TC-20LB30

LH32 Chassis

Power Source Power Consumption

LCD 19.6-inch (499 mm), Diagonal 4 : 3 aspect ratio LCD panel

Screen Size 15.79 " (401 mm) (W) × 11.77 " (299 mm) (H) Channel Capability VHF-12 : UHF-56 : Cable-125 Sound

Speaker 4 cm × 10 cm, 2 pcs, 16 W Audio Output 6 W [3 W + 3 W] (10 % THD)

Headphones M3 (3.5 mm) Jack × 1 FEATURES 3D Y/C Digital Comb Filter, CLOSED CAPTION, V-Chip, SD/PC Card slot Operating Conditions Temperature : 41 °F - 95 °F (5 °C - 35 °C)

Connection Terminals

INPUT VIDEO (RCA PIN Type × 1) × 2 1.0 Vp-p (75 W)

COMPONENT VIDEO INPUT Y×1 1.0 Vp-p (including synchronization)

Dimensions ( W × H × D )

Including TV Stand 24 3/4 “ × 19 51/64 “ × 10 15/64 ”

TV Set Only 24 3/4 “ × 16 29/64 “ × 3 37/64 ”

Mass (Weight) 20.7 lb. (9.4 kg) Net

C 120 V, 60 Hz

verage use : 58 W Stand-by condition : 0.10 W Power off : 0.08 W

VGA (640 × 480 pixels)

Humidity : 5 % - 90 % RH (non-condensing)

S-VIDEO (MINI DIN 4pin × 1) × 2 Y : 1 Vp-p (75 W ), C : 0.286 Vp-p (75

UDIO L-R (RCA PIN Type × 2) × 2 0.5 Vrms

PB/PR×1 ± 0.35 Vp-p

UDIO L-R (RCA PIN Type × 2) × 1 0.5 Vrms

(629 mm × 503 mm × 260 mm)

(629 mm × 418 mm × 91 mm)

TC-20LB30

CONTENTS

Page Page

1 Safety Precautions 3

1.1. General Guidelines

2 Prevention of Electro Static Discharge (ESD) to

Electrostatically Sensitive (ES) Devices 3 About lead free solder (PbF) 4 Self-check function

4.1. How to access

4.2. Screen display

5 Chassis Board Layout 6 Disassembly for Service

6.1. Pedestal ass’y

6.2. Rear cover

6.3. TA-Board

6.4. A-Board

6.5. Power unit

6.6. V-Board

6.7. Speaker (left and right)

6.8. JG-Board and JG-Board bracket

6.9. GS-Board

6.10. Main chassis

6.11. LCD panel

7 Location of Lead Wiring 8 Adjustment method

8.1. How to enter into adjustment mode

8.2. Cancellation

8.3. Contents of adjustment mode

10 10 11 11

12 13

13 13 13

3 4 5

5 5

6 7

7 7 7 8 8 9 9

8.4. Video Signal Level Adjustment

8.5. LCD GAMMA Adjustment

8.6. MTS Adjustment

9 Conductor Views

9.1. A-Board

9.2. JG-Board

9.3. GS, TA and V-Board

10 Block and Schematic Diagram

10.1. Schematic Diagram Notes

10.2. Power Block Diagram

10.3. Signal Block Diagram

10.4. A-Board (1 of 5) Schematic Diagram

10.5. A-Board (2 of 5) Schematic Diagram

10.6. A-Board (3 of 5) Schematic Diagram

10.7. A-Board (4 of 5) Schematic Diagram

10.8. A-Board (5 of 5) Schematic Diagram

10.9. JG-Board (1 of 2) Schematic Diagram

10.10. JG-Board (2 of 2) Schematic Diagram

10.11. GS, TA and V-Board Schematic Diagram

11 Parts Location & Mech anica l Replacement Parts List

11.1. Parts Location

11.2. Packing Exploded View

11.3. Mechanical Replacement Parts List

12 Repla ceme nt Parts List

12.1. Replacement Parts List Notes

12.2. Electrical Replacement Parts List

14 14 15

17 20 22

25 26 27 28 29 30 31 32 33 34 35

37 38 39

40 41

1 Safety Precautions

1.1. General Guidelines

1. When servicing, observe the original lead dress. If a short circuit is found, replace all parts which have been overheated or damaged by the short circuit.

2. After servicing, see to it that all the protective devices such as insulation barriers, insulation papers shields are properly installed.

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

TC-20LB30

1.1.1. Leakage Current Cold Check

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

2. Measure the resistance value, with an ohmmeter, between the jumpered AC plug and each exposed metallic cabinet part on the equipment such as screwheads, connectors, control shafts, etc. When the exposed metallic part has a return path to the chassis, the reading should be between 1MW and 5.2MW.

When the exposed metal does not have a return path to the chassis, the reading must be

Figure 1

1.1.2. Leakage Current Hot Check (See Figure 1.)

1. Plug the AC cord directly into the AC outlet. Do not use an

isolation transformer for this check.

2. Connect a 1.5kW, 10 watts resistor, in parallel with a 0.15µF

capacitors, between each exposed metallic part on the set and a good earth ground such as a water pipe, as shown in Figure 1.

3. Use an AC voltmeter, with 1000 ohms/volt or more

sensitivity, to measure the potential across the resistor.

4. Check each exposed metallic part, and measure the

voltage at each point.

5. Reverse the ACplugintheACoutlet and repeat eachof the

above measurements.

6. The potential at any point should not exceed 0.75 volts

RMS. A leakage current tester (Simpson Model 229 or equivalent) may be used to make the hot checks, leakage current must not exceed 1/2 milliamp. In case a measurement is outside of the limits specified, there is a possibility of a shock hazard, and the equipment should be repaired and rechecked before it is returned to the customer.

2 Prevention of Electro Static Discharge (ESD) to

Electrostatically Sensitive (ES) Devices

Some semiconductor (solid state) devices can be damaged easily by static electricity. Such components commonly are called Electrostatically Sensitive (ES) Devices. Examples of typical ES devices are integrated circuits and some field-effect transistors and semiconductor "chip" components. The following techniques should be used to help reduce the incidence of component damage caused by electro static discharge (ESD).

1. Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off any ESD on your body by touching a known earth ground. Alternatively, obtain and wear a commercially available discharging ESD wrist strap, which should be removed for potential shock reasons prior to applying power to the unit under test.

2. After removing an electrical assembly equipped with ES devices, place the assembly on a conductive surface such asalminum foil, to prevent electrostatic charge buildup or exposure of the assembly.

3. Use only a grounded-tip soldering iron to solder or unsolder ES devices.

4. Use only an anti-static solder removal device. Some solder removal devices not classified as "anti-static (ESD protected)" can generate electrical charge sufficient to damage ES devices.

5. Do not use freon-propelled chemicals. These can generate electrical charges sufficient to damage ES devices.

6. Do not remove a replacement ES device from its protective package until immediately before you are ready to install it. (Most replacement ES devices are packaged with leads electrically shorted together by conductive foam, alminum foil or comparable conductive material).

7. Immediately before removing the protective material from the leads of a replacement ES device, touch the protective material to the chassis or circuit assembly into which the device will be installed.

TC-20LB30

Caution

Be sure no power is applied to the chassis or circuit, and observe all other safety precautions.

8. Minimize bodily motions when handling unpackaged replacement ES devices. (Otherwise hamless motion such asthe brushing together of your clothes fabric or the lifting of your foot from a carpeted floor can generate static electricity (ESD) sufficient to damage an ES device).

3 About lead free solder (PbF)

Note: Lead is listed as (Pb) in the periodic table of elements. In the information below, Pb will refer to Lead solder, and PbF will refer to Lead Free Solder. The Lead Free Solder used in our manufacturing process and discussed below is (Sn+Ag+Cu). That is Tin (Sn), Silver (Ag) and Copper (Cu) although other types are available.

This model uses Pb Free solder in it’s manufacture due to environmental conservation issues. For service and repair work, we’d suggest the use of Pb free solder as well, although Pb solder may be used.

PCBs manufactured using lead free solder will have the PbF within a leaf Symbol

Caution

· Pb free solder has a higher melting point than standard solder. Typically the melting point is 50 ~ 70 °F (30~40°C) higher.

· ·

Please use a high temperature soldering iron and set it to 700 ± 20 °F (370 ± 10 °C).

· Pb free solder will tend to splash when heated too high (about 1100 °F or 600 °C).

· ·

If you must use Pb solder, please completely remove all of the Pb free solder on the pins or solder area before applying Pb solder. If this is not practical, be sure to heat the Pb free solder until it melts, before applying Pb solder.

· After applying PbF solder to double layered boards, please check the component side for excess solder which may flow onto

· ·

the opposite side. (see figure below)

Suggested Pb free solder

There are several kinds of Pb free solder available for purchase. This product uses Sn+Ag+Cu (tin, silver, copper) solder. However, Sn+Cu (tin, copper), Sn+Zn+Bi (tin, zinc, bismuth) solder can also be used.

stamped on the back of PCB.

4 Self-check function

When phenomena like "the power fails from time to time" or "the video/audio fails from time to time" can not be confirmed at the time of servicing, the self-check function can be used to confirm the occurrence and to limit the scope for the defective circuits.Also, when "the power fails from time to time", display on the screen can be used to confirm the occurrence and to limit the scope for the defective circuits.

Any programmed channels, channels caption data and some other user defined settings will be erased and return to factory setting.

4.1. How to access

4.1.1. Access

Produce TV reception screen and, while pressing [VOLUME-] button on the main unit, press [SLEEP] button on the remote controller unit simultaneously.

4.1.2. Exit

When one of the buttons for channel selection etc. is pressed, the display returns to the normal screen.

4.2. Screen display

TC-20LB30

Display Ref .No. Description P.C.B. TNR TU001 Tuner TA-Board SOUND IC2320 Sound control A-Board AVSW IC3001 AV Switch A-Board MTS IC2201 Multi Sound Processor TA-Board GLP IC4014 LCD Processor A-Board GC3 IC4012 Global Core A-Board TEMP IC1008 Temperature Sensor A-Board MEMORY IC1002 EEPROM A-Board JPEG IC6513 MCU (JPEG) JG-Board

TC-20LB30

5 Chassis Board Layout

Board Name Function A-Board Main (AV Switch, Audio, MCU, Global Core, AV connector ) GS-Board SD card slot JG-Board JPEG Viewer, PC card slot V-Board Headphone, Speaker, Remote Reciever, LED TA-Board Tuner, MTS Power Unit Power (AC/DC), Switch

None serviceable. Power Unit should be exchanged for service.

6 Disassembly for Service

6.1. Pedestal ass’y

1. Lay down the main unit so thatthe rear cover faces upward.

6.2. Rear cover

1. Remove the pedestal ass´y. (See 6.1.)

2. Remove the fixing screws (12pcs

3. Remove the rear cover.

TC-20LB30

and 2pcs ).

2. Remove the fixing screws (2pcs ) and remove the hinge cover.

3. Remove the fixing screws (2pcs ).

4. Remove the pedestal ass´y.

6.3. TA-Board

1. Remove the rear cover. (See 6.2.)

2. Remove the fixing screw (1pcs

3. Remove the TA-Board.

TC-20LB30

6.4. A-Board

1. Remove the rear cover. (See 6.2.)

2. Remove the TA-Board. (See 6.3.)

3. Disconnect the couplers (A5, A7, A8 and A9) and the flexible cable (A15).

4. Remove the fixing screws (2pcs ).

5. Remove the A-Board shield case.

6. Remove the fixing screws (4pcs

7. Remove the A-Board.

Case 1.

Bond is applied to power unit.

Case 2.

Barrier is attached in chassis frame.

6.5. Power unit

1. Remove the rear cover. (See 6.2.)

2. Disconnect the couplers (CN1 and CN2).

3. Remove the fixing screws (6pcs

4. Remove the power unit.

When exchange the power unit, xonfirm the TV unit is case 1 or case2.

If there is no Barrier attachment, Bond should be applied the same as original power unit (as shown in figure).

6.6. V-Board

1. Remove the rear cover. (See 6.2.)

2. Remove the fixing screw (3pcs

3. Disconnect the couplers (V1 and V5).

4. Remove the V-Board.

6.7. Speaker (left and right)

TC-20LB30

1. Remove the rear cover. (See 6.2.)

2. Disconnect the coupler (V5). (See 6.6.)

3. Remove the fixing screws (8pcs

4. Remove the speaker (left and right).

TC-20LB30

6.8. JG-Board and JG-Board

bracket

1. Remove the rear cover. (See 6.2.)

2. Remove the fixing screws (4pcs

3. Remove the JG-Board shield case.

4. Disconnect the couplers (JG3 and JG6).

5. Remove the JG-Board.

6. Remove the fixing screws (4pcs

7. Remove the JG-Board bracket.

6.9. GS-Board

1. Remove the rear cover. (See 6.2.)

2. Remove the fixing screws (2pcs

3. Disconnect the coupler (JG3).

4. Remove the GS-Board shield case.

5. Remove the fixing screws (2pcs ).

6. Remove the GS-Board bracket.

7. Disconnect the coupler (GS4).

8. Remove the GS-Board.

6.10. Main chassis

1. Remove the rear cover. (See 6.2.)

2. Disconnect the couplers (A5, A7, A8 and CN1) and the flexible cable (A15).

3. Unlock the cable hooks to free the cable.

4. Remove the fixing screws (2pcs ).

5. Remove the button cover.

8. Remove the fixing screws (5pcs ).

9. Remove the main chassis.

6.11. LCD panel

1. Remove the main chassis. (See 6.10.)

2. Remove the JG-Board and the JG-Board bracket. (See 6.8)

3. Remove the fixing screws (4pcs

4. Remove the LCD panel.

TC-20LB30

6. Remove the fixing screws (4pcs ).

7. Remove the fixed metal.

TC-20LB30

7 Location of Lead Wiring

8 Adjustment method

8.1. How to enter into adjustment mode

While pressing [VOLUME- ] button of the main unit, press [RECALL] button of the remote control three times in a row (within 2 seconds).

8.1.1. Adjustment method.....Use the remote control.

“1” button...Main items Selection in forward direction “2” button...Main items Selection in reverse direction “3” button...Sub items Selection in forward direction “4” button...Sub items Selection in reverse direction “VOL” button...Value of sub items change in forward direction (

), in reverse direction ( )

TC-20LB30

8.2. Cancellation

Switch off the power with the [POWER] button on the main unit or the [POWER] button on the remote control.

8.3. Contents of adjustment mode

· Value is shown as a hexadecimal number.

· ·

· Preset value differs depending on models.

· ·

· After entering the adjustment mode, take note of the value in each item before starting adjustment.

· ·

Main item Sub item Remarks Sample Data

MAIN Y-GAIN Video level (RF, video, component) 0A

B-Y Video level (RF, video, component) C5 R-Y Video level (RF, video, component) 4B

SUB COLOR Sub color 1C

TINT Sub tint 05 BACK-L Sub Back light 173 BRIGHT Sub Bright 800 B-Y-G B-Y Gain 3D R-Y-A R-Y demodulation axis 0D TEMP Temperation data 044

GAMMA R-GAIN R-Gain for test pattern (100% white) F8

G-GAIN G-Gain for test pattern (100% white) F7 B-GAIN B-Gain for test pattern (100% white) FF R-CENT R-Gain for test pattern (50% white) BC G-CENT G-Gain for test pattern (50% white) 80

B-CENT B-Gain for test pattern (50% white) 2C OPT OPT00 (TV) 00 RM CODE Remote control code A or B A MTS MTSIN RF Audio input level 29

SEPAH Stereo separation Hi 20

SEPAL Stereo separation Low 0A

TC-20LB30

8.4. Video Signal Level Adjustment

Instrument Name Connect to Remarks

1. Remote control

2. RF signal

3. SG

1. Receive studio color bar by RF signal input. (Viewing mode: standard, LCD AI: OFF, Back Light: +30 )

2. Enter into Main adjustment in the adjustment mode, push for one second "8" on the remote control and make automatic adjustment of video signal level.

8.5. LCD GAMMA Adjustment

Instrument Name Connect to Remarks

1. Remote control

2. LCD WB meter (Minolta CA-110 equivalent)

3. Communication jig

4. Computer for external control

· After 30 minutes aging perform the white balance adjustment.

· ·

1. Enter into GAMMA adjustment in the adjustment mode and measure the WHITE brightness data to check that it is higher than 300 cd /m

(Viewing mode: standard, LCD AI: OFF, Back Light: +30 ) (When it is below 300 cd /m

2. Measure white brightness data and chromaticity coordinate, decide "Standard color 1" and "Standard color 2" at the peak adjustment.

3. Set up objective of coordinate, select twocolor R-GAINor G-GAIN or B-GAIN except the decided standard color 1 (=0xff) in the condition of displaying white color. When adjustment is not completed normal, make it by selecting two color R-GAIN or G-GAIN or B-GAIN except the decided standard color 2 (=0xff).

<< objective of coordinate (x0, y0) = (0.277 ± 0.002, 0.279 ± 0.002) >>

, make re-measurement in 30 minutes after cold-on.)

Standard color 1/2 RED GREEN BLUE

x direction B-GAIN [1] R-GAIN [2] R-GAIN [1] y direction G-GAIN [2] B-GAIN [1] G-GAIN [2]

· When turn up R-GAIN and G-GAIN chromaticity coordinate get bigger and when turn up B-GAIN chromaticity coordinate get

· ·

smaller.

· When adjust for remote control select R-GAIN, G-GAIN and B-GAIN by pressing "3" and "4", and change the value by VOL

· ·

and "VOL ".

· Adjust preferentially [1] ,converge smoothly.

· ·

4. Set up objective of coordinate, select R-CENT and B-CENT, set the standard color GREEN (=0x80) in displaying GRAY color.

Standard color GREEN Adjustment direction

x direction R-GAIN When turn up chromaticity coordinate get bigger. y direction B-GAIN When turn up chromaticity coordinate get smaller.

· When adjust for remote control select R-GAIN, G-GAIN and B-GAIN by pressing "3" and "4", and change the value by "VOL

· ·

" and "VOL ".

5. Write the values converge objective of coordinate above in the gamma data part of EEPROM.

· When adjusting by the remote control, push for one second or more "8" on the remote control in R-CENT, G-CENT and B-

· ·

CENT. (OSD is flash red at upper left of display.)

6. Check that the chromaticity coordinate, at WHITE and GRAY, are within the values given below. x= 0.277 ± 0.003 y= 0.279 ± 0.003

8.6. MTS Adjustment

Caution:

MTS adjustment shall be after the aging of 30 minutes or longer.

8.6.1. RF Audio Input level Adjustment

Instrument name Connection Remarks

1. Filter jig

2. RF signal generator

3. RMS voltage meter

1. Apply following RF signal at Antenna input. VIDEO : Flat field, 30 % modulation AUDIO : 300 Hz, 100 % modulation, monaural (70 dB ± 5 dB, 75 W Open, P/S 10 dB)

Note:

Make sure 75 us PRE-EMPHASIS is off.

2. Enter into MTSIN (MTS) adjustment mode.

3. Adjust "MTSIN" data (Input level) until the RMS voltage meter indicates 106 mVrms ± 6 mVrms.

TP3572 - GND RF ANT. INPUT Filter jig

TC-20LB30

Filter jig

8.6.2. Stereo Separation Adjustment

Instrument name Connection Remarks

1. RF signal generator

2. Oscilloscope

1. Select STEREO mode in the AUDIO Menu.

2. Set “Audio volume” DAC to “40”.

3. Apply following RF signal at Antenna input. VIDEO : Flat field, 30% modulation AUDIO : 300Hz sine wave, 30% modulation, STEREO (LEFT only)

(70dB ± 5dB, 75 W OPEN, P/S 10dB)

Note:

After setting 30% modulation with PL SW and NR SW off, turn PL SW and NR SW on.

4. Enter into SEPAL (MTS) adjustment mode.

5. Adjust "SEPAL" data (Low-level separation) until the amplitude becomes minimum.

6. Apply following RF signal at Antenna input. VIDEO : Flat field, 30% modulation AUDIO : 3kHz sine wave, 30% modulation, STEREO (LEFT only)

(70dB ± 5dB, 75W OPEN, P/S 10dB)

Note:

After setting 30% modulation with PL SW and NR SW off, turn PL SW and NR SW on.

7. Enter into SEPAH (MTS) adjustment mode.

8. Adjust "SEPAH" data (High-level separation) until the amplitude of the waveform is minimum.

9. Repeat steps 3. to 8. until Low-level separation and High-level separation satisfy above-mentioned conditions.

10. After adjustment, set “Audio“ volume “DAC” to “16“.

Note:

The separation must be more than 20 dB at 300Hz and 3kHz.

RF ANT. INPUT VIDEO2 R VIDEO2 R (RCA jack)-GND

10 Block and Schematic Diagram

10.1. Schematic Diagram Notes

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