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
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Contents
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BOARD
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1
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BACK LIGHT_SOS
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P BOARD
LCD Panel |
3
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PANEL POWER_SOS
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A BOARD
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4
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DTV12V_SOS
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P/A BOARD
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7
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SUB 3.3V_SENSE
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A BOARD
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9
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SOUND SOS
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A BOARD
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13
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EMERGENCY_SOS
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A BOARD
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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.
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.
