Panasonic TH-37PX60U, Technical Manual

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SOS Circuit Overview
10 Blinks SOS: IC5600 is a 3.3V regulator located on the A board. Its output is monitored by
IC1100. If the 3.3V is not present at pin 67, the MPU shuts down the unit. The power LED blinks 10
times.
12 Blinks SOS: On the A board, transistor Q2301 monitors the Sound 15V line and the operation of
the audio power amplifier IC2301. If the audio output circuit, IC2301, or the 15V lines develops a
short to ground, transistor Q2301 goes into conduction and applies a high to pin 118 of the MPU,
IC1100, triggering a SOS condition. The power LED blinks 12 times.
12 Blinks SOS: We have also discovered that 12 blinks of the power LED may also be caused by a
defective SS board. To determine the source of the shutdown, disconnect the connector D5 and
connect the unit to the AC source. If the panel turns on and the LEDs of the SS and SC boards stay
on, the problem is on the A board. If the panel does not stay on, the problem is likely to be the SS
board.
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