Panasonic TH-65PX600U Service Manual page 56

Drive Reset Circuit
DRV RST input to IC9500 and IC9003 must be high for the unit to operate. The D board
provides the 5V source needed to power the C boards. On the C board, the 5V is routed
back to the D board to activate the 5V SENSE circuit. A voltage divider consisting of
R9369 and R9371 causes the collector of transistor Q9301 to become low. As a result, the
base voltage of Q9302 also becomes low causing its collector to become high. The output
voltage is applied to IC9500 and IC9003 as DVR RST.
The operation of the 5V SENSE circuit of the C2 board is the same.
The diodes D9301 and D9302 are used to isolate the two 5V SENSE circuits.
When the 5V SENSE circuit does not detect 5V from any of the C boards, the DVR RST
output becomes low. The unit goes into shutdown and the power LED blinks 6 times.
Test Point TP9387 is the ideal location to check for DRV RST.
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