Wednesday, February 18, 2015

PANASONIC TC-20LA5 - TC-20LE5 LCD TV SERVICE MODE - DISASSEMBLING AND POWER SUPPLY CIRCUIT

PANASONIC TC-20LA5 /TC-20LE

LCD TV


 SERVICE MODE - DISASSEMBLING AND POWER SUPPLY CIRCUIT 

SERVICE MODE 
While pressing [VOLUME-] button of the main unit, press [RECALL] button of the remote control transmitter three times in a row
(within 2 seconds).
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
EXIT SERVICE MODE
Switch off the power with the [POWER] button on the main unit or the [POWER] button on the remote control.
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.
How to access
Access
Produce TV reception screen and, while pressing [VOLUME-] button on the main unit, press [SLEEP] button on the remote controller unit simultaneously.
Exit
When one of the buttons for channel selection etc. is pressed, the display returns to the normal screen
Measurements and Adjustments
Video Signal Level Adjustment
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 plant adjustment mode, push for one second "8" on the remote controller and make automatic  adjustment of video signal level.
 LCD GAMMA Adjustment
 After 30 minutes aging complete white balance adjustment.
1. Enter into WB adjustment in the plant adjustment mode and measure the WHITE brightness data to check that it is higher than 300 cd /m2. (Viewing mode: standard, LCD AI: OFF, Back Light: +30 ) (When it is below 300 cd /m2, make re-measurement in 30 minutes after cold-on.)
2. Measure white brightness data and chromaticity coordinate, decide "Standard color 1" and "Standard color 2" at adjustment peak.
3. Set up objective of coordinate, select two color R-GAIN or G-GAIN or B-GAIN but no use standard color (=0xff), display white color. When adjustment is not required normal, select two color R-GAIN or G-GAIN or B-GAIN but no use standard color (=0xff). << objective of coordinate (x0, y0) = (0.277 ± 0.002, 0.279 ± 0.002) >>
 When turn up R-GAIN and G-GAIN chromaticity coordinate get bigger, 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 for "volume +" and "volume -".
Adjust preferentially [1] ,converge simply.
4. Set up objective of coordinate, select R-CENT and B-CENT, set standard color green (=0x80), display gray color.
When adjust for remote control select R-GAIN, G-GAIN and B-GAIN by pressing "3" and "4", and change for "volume +" and "volume -".
5. Write the values converge objective of coordinate above in the gamma data part in EEPROM.
When adjust for remote control, push for one second "8" on the remote controller with R-GAIN, G-GAIN and B-GAIN. (OSD is flash red on 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.
MTS Adjustment
MTS adjustment shall be after the aging of 30 minutes or longer
RF Audio Input level Adjustment
1. Apply following RF signal at Antenna input.
VIDEO : Flat field, 30 % modulation
AUDIO : 300 Hz, 100 % modulation, monaural
(70 dB ± 5 dB, 75 , P/S 10 dB)
Note:
Make sure 75 us PRE-EMPHASIS is off.
2. Adjust "MTSIN" data (Input level) until the RMS voltage meter indicates 106 mVrms ± 6 mVrms
Stereo Separation Adjustment
1. Select STEREO mode in the AUDIO Menu.
2. Set ìAudio volumeî DAC to ì40î.
3. Apply following RF signal at Antenna input.
VIDEO : Flat field, 30% modulation
AUDIO : 300Hz, 30% modulation, STEREO (LEFT only)
(70dB ± 5dB, 75  OPEN, P/S 10dB)
Note:After setting 30% modulation with PL SW and NR SW off, turn PL SW and NR SW on.
4. Adjust "SEPAL" data (Low-level separation) until the amplitude.
5. Apply following RF signal at Antenna input.
VIDEO : Flat field, 30% modulation
AUDIO : 3kHz, 30% modulation, STEREO (LEFT only)
(70dB ± 5dB, 75 OPEN, P/S 10dB)
Note:After setting 30% modulation with PL SW and NR SW off, turn PL SW and NR SW on.
6. Adjust "SEPAH" data (High-level separation) until the amplitude of the waveform on the oscilloscope is minimum.
7. Repeat steps 3. to 6. until Low-level separation and High-level separation satisfy above-mentioned conditions.
Note:
The separation must be more than 20 dB at 300Hz and 3kHz.

DISASSEMBLE
1. Lay down the unit so that the rear cover faces upward.
2. Remove the 4 screws.
3. Remove the photo stand cover assembly.
4. Remove the 2 screws.
5. Remove the stand metal.

Removing the pedestal assembly
1. Remove the 4 screws.
2. Remove the pedestal assembly.
Removing the rear cover
1. Remove the 2 screws.
2. Remove the 8 screws.
3. Remove the rear cover.


Removing the control button assembly
1. Remove the 2 screws.
2. Remove the control button assembly.

Removing the chassis assembly
1. Remove the 3 screws.
2. Disconnect Inverter couplers and Panel coupler and clam
A11-Panel coupler wire.
3. Remove the chassis assembly

Removing the A-Board, TABoard, and Power unit
1. Remove the 12 screws.
2. Remove the A-Board, TA-Board, and Power unit.

Removing the speaker and the pedestal bracket
1. Remove the 12 screws.
2. Remove the pedestal bracket.
3. Disconnect speaker terminal.
4. Remove the speaker.

Removing the LCD panel, RBoard, and V-Board
1. Remove the 4 screws.
2. Remove the LCD Panel.
3. Remove the 2screw.
4. Remove the R-Board and V-Board.

Removing the LCD mount metal
1. Remove the 4 screws.
2. Remove the LCD mount metal.


SMPS POWER SUPPLY CIRCUIT 
CLICK ON THE IMAGE TO ZOOM IN