Sunday, November 08, 2015

PANASONIC TC-L42D2 - TC-L37D2 - TC-L42U25 - TC-L37U22 - TC-L32U22 - TC-L37X2 - TC-L32X2 - TC-L22X2 - TC-L37C22 - TC-L32C22 LED BLINKING PROBLEMS AND HOW TO TROUBLESHOOT

PANASONIC TC-L42D2 - TC-L37D2 - TC-L42U25 - TC-L37U22 - TC-L32U22 - TC-L37X2 - TC-L32X2 - TC-L22X2 - TC-L37C22 - TC-L32C22 

LED BLINKING PROBLEMS AND HOW TO 

TROUBLESHOOT 

LED BLINKINB AND CAUSES
Blinking times
Contents
BOARD
1

BACK LIGHT_SOS

P BOARD
LCD Panel
3
PANEL POWER_SOS
A BOARD
4
DTV12V_SOS
P/A BOARD
7
SUB 3.3V_SENSE
A BOARD
9
SOUND SOS
A BOARD
13
EMERGENCY_SOS
A BOARD

1 BLINK

When the power button is pushed , IC8001 outputs the TVSUB ON command to turn on the main power supply and output the power_on voltages. Upon confirmation of the output voltages of the power supply, IC8001 sends the Inverter_ON command to P board. On the power supply board, the Inverter_On command enters IC7800, the inverter control IC. IC7800 then outputs the trigger that turns on the oscillator IC7801. The sine wave output of the oscillator is provided to the switching transistors connected to T7801 to generate a magnetic field. The AC output at the secondary of T7801 is provided to the LCD panel via the connectors P5, P6, P7 and P8 to power the backlights. When the inverter is operating properly, the inverter SOS input of the micro is pulled low. If a malfunction occurs, a detection circuit located within IC7800 sends out a SOS command to alert the inverter control IC, IC7800. IC7800 conveys the SOS message to the main micro IC8001 by keeping the inverter SOS input high. The TV shuts down and the power LED blinks 1 time
TROBLSHOOTING 1 BLINK
Is the Inverter_on command (3V) at pin 3 of CN A03 before the TV shuts down? > Is there DTV12V at pin 4 of CN P2 before the TV shuts down? > P board (Without DTV12V, the inverter circuit does not work)
Does pin 4 of CN A03 remain high before the TV shuts down? > A board
Is there AC output at pin 1 and 2 of CN P5, P6, P7 and P8 before the TV shuts down? > P board (The inverter circuit is malfunctioning)
3 AND 7 BLINKS
The A Board is responsible for the regulation, distribution and dissemination of all secondary voltages derived from the DTV12V output of the P Board. When the unit is powered, the 12V output of the P board biases the transistor Q5613 into operation, causing its collector to become “low”. As a result the transistors Q5612 turns off. The high at the collector of Q5612 causes IC5606, IC5608, IC5610, and D5670 to operate and provide the SUB5V, 1.8V, 1.2V, and IC4700 detects the loss of voltage and provides an output to IC8001 to shut the unit down. The power LED blinks 3 times.
The SUB3.3V is monitored directly by the CPU, IC8001. If it is shorted or missing, the unit shuts down and the power LED blinks 7 times. IC8001 turns off the AC power by disabling the SUB_ON command that turns on the AC relay.
TROBLE SHOOTING 3 AND 7 BLINK
Is there 12V at pin 4 of CN P2 before the TV shuts down? >Is pin 4 of CN P2 shorted? > P board (DTV 12V supply problem.)
Is there 13.7 V output at pin 8 or 9 of IC4800? Is there 2.5V output at pin 2 or 3 of IC4800? > A board
Disconnect the connector A03 > Is pin 4 of CN P2 shorted? > A board
4 BLINK


When the unit is turned on, the DTV source of the P board is provided to the A board for conversion into other voltages. A zener diode at the base of transistor Q5613 protects against over-current condition. When the DTV12V source drops to a predetermined level, the zener diode turns off causing Q5613 to turn off and Q5612 to turn on. The input to IC8001 goes low resulting in the shutdown of the unit and 4 blinks of the power LED.
TROUBLESHOOTING 4 BLINKS
Is there 12V at pin 4 of CN P2 before the TV shuts down? > Is pin 4 of CN P2 shorted? > P board (DTV 12V supply problem.)
Disconnect the connector A03. Is pin 4 of CN P2 shorted? > A board
9 BLINKS

On the A board, the MPU (IC8001) monitors the operation of the audio power amplifier IC2106. If IC2106 or one of the speakers develops a short circuit, a high is output to IC8001 to trigger a shutdown and 9 blinks of the power LED. When a 9 blinks shutdown occurs, disconnect the speakers one at a time and turn the unit on. If the problem remains, replace the A board. If it goes away, the disconnected speaker is the problem.
In the event the unit shuts down and the power LED blinks nine times, check for an improper connection of connector A21/TC05. The shutdown occurs due to no communication between the TC-Board and A-Board. A defective TCON board may also be the cause for the 9 blink code.