Other model numbers PN43D450 and PN43D450A2DXZC.

This TV had no power at all.  No LED indicator and no standby voltage.

Lots of threads on badcaps indicated problems with transistors shorting on the X-Main board which causes the power supply to shut down.  Symptoms would be repeated clicking of the relay and a flashing LED.  Older versions of this TV had a firmware problem which may have contributed to this failure.

My TV didn’t make it to this step with the lack of standby voltage.  There is a fast track troubleshooting guide and the first step is to check for the 5V standby voltage.

The power supply board (part #BN44-00442A) is suspect but there were no blown caps and the fuse was ok.  I had a power supply board for a 51″ TV of the same series (part#BN44-00443A) and the PCB itself was identical.  I installed it in and the TV powered up.

I’d like to debug the old, non-working board but without a schematic, it is a bit difficult.