The set showed no signs of life. No standby light, no reaction to the power switch.
It is built like a monitor, with uncountable screws and a full metal cover over the boards. And it has reasonably sized speakers! :-)
I quickly found the 5V standby voltage to be missing completely. I removed the power supply and connected it to the isolation transformer for further checks. Never work on switching power supplies without an iso transformer!
The main reservoir caps were fully charged with over 300V. The FET, which controls the primary winding of the stand-by transformer had a short between gate and source. That's not good, because it switches the full main voltage and the PWM control chip is connected to the gate. I suspected that the chip did not survive this attack.
To be sure that a shorted transformer primary winding wasn't the reason for the dead FET I used my ring tester. Two green LEDs indicated a perfectly fine winding.
Well, I first replaced the FET, which is a cheap standard part. Not working. There was no voltage at the source pin. The whole stand-by section had no voltage anywhere. Tracing back to the main capacitors I came across a blown 0.1 Ohm resistor hidden under the large aluminum cooler. It is used as a fuse for fatal failures, I think, and cuts off all power sections. For testing I only had a 0.22 emitter resistor from an amplifier. Still not working.
The PWM chip read DAP6A. I couldn't find anything under that type, until, after some research, I found out that it is actually called DAP006. Datasheet was available and I probed the chip. Uh oh, it had a short between ground and Vss.
Thanks to ebay I found (only!) one dealer in Great Britain for the chip and one for the resistor.
The replacement chip worked fine and the TV is back alive:
Three parts replaced this time:
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