Panasonic TC-P50S1 User Manual

Page of 77
Slide #42
3 Blinks/4 Blinks Error Code
Since the IC (IC9805) that generates the monitored 3.3V for 3 blinks 
condition and the IC (IC9003) that detects this condition are both located on 
the A board, then the A board is the only suspect when the TV shuts down 
and the power LED blinks 3 times.
Replace the A board.
Primarily the P board causes 4 blinks, followed by the A board.
To troubleshoot a 4 blinks condition, measure the voltage at pin 12 of 
connector P25. If the voltage goes high, the P board is the problem. If the 
voltage stays low, then the A board is the problem. 
4 Blinks Error Code
3 Blinks Error Code