Protection Circuit - Sanyo LCD-30CA1Z Service Manual

Protection Circuit

Sub CPU (IC801) is programmed that the TV set goes to standby mode when there is circuit
failure as below.
1. Power fail-1 (Pin-82 of Sub CPU): Detected the low voltage failure in the TV set. (2.5V, 3.3V, 5.0V)
2. Power fail-2 (Pin-83 of Sub CPU): Detected the middle voltage failure in the TV set. (9V, 12V, 30V)
3. Power fail-5 (Pin-84 of Sub CPU): Detected the failure of Audio AMP.
4. Temperature fail (Pin-92 of Sub CPU): Detected the failure of Temperature Sensor.
■ Releasing the protective circuit and restoring power supply
To release the protective circuit and restore power supply, turn the power to the TV set OFF and then ON again via
the POWER ON-OFF button on the remote control or the TV set. This will work only if the power supply trouble was
temporary. If there is permanent trouble such as a damaged circuit, power cannot be restored and the circuit will
have to be repaired.
■ When operating the Protection Circuit, On-screen Display massage is displayed and the LED blinks.
Massage of On-screen Display
1. Temperature Failure
When the internal temperature exceeds normal, following message is displayed for 10 seconds and LCD TV will
be turned off automatically.
Internal temperature is too high.
Set shuts down.
2. Fan Trouble
When the internal cooling fan has trouble, following message is displayed for 10 seconds in every 10 minutes.
Internal fan is in trouble, not working properly.
Power LED Blinking
When IC801 detects power failure, the Power LED will blink to indicate a power failure has occurred. The number of
blinks will be determined by the type of failure detected as shown below.
1. Power fail-1 (Low voltage failure): One time (in Green).
2. Power fail-2 (Middle voltage failure): Two times (in Green).
3. Power fail-1 and Power fail-2: Three times (in Green).
4. Power fail-5 (Audio AMP. failure): One time (in Yellow).
5. Temperature Failure: Two times (in Red).
Note: In case of overlapped failure, 1 to 5 is repeated in turn.
If power failure is detected 3 times within 15 minutes, the TV set will enter the standby mode and cannot be
switched on. To reset the operating programme of the Sub CPU, it is necessary to disconnect the AC cord
for a short time.
(Normal=High, Failure=Low)
(Normal=High, Failure=Low)
(Normal=Low, Failure=High)
Warning!
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