Sony XR-65A95L no power due to logic board issue

[joliver82]

Hi guys!

I'm trying to repair a TV that a friend gave me recently. Lightning struck next to his house and broke the TV apart from more electronic devices.

First of all I've checked the power supply and it works as expected. I removed the logic board and shorted the 3.3v standby output to TCON_ON and POWER_ON and every voltage was generated as expected (12v and 25v for logic board and 32v for TCON).

When trying to boot the TV normally (having the board connected), the TCON_ON signal is not generated from it which made me think there's some issue in the logic board.

I've been checking it and I've found two potential issues. First of all I found two burned SMD components which I need to identify. Both are located near one of the HDMI ports, so I searched around the other HDMI ports and found the same components. I'm attaching pictures of them (the non-burned components) in case you can help me identify them:

I'm talking about the 2 pin component marked with "F2". This one I think it's a diode but not sure which.


Here I'm talking about the one marked as "D·I€". Probably a transistor? The pin below right is connected to ground, just in case this helps you.


Any help identifying the components is appreciated

I've been reviewing the whole board. All fuses and 0 Ohm resistors are OK. I've looked for shorts also checking all inductors and capacitors. The only weird stuff I've found is the output of what I think is a buck converter which has 1ohm resistance to ground. Attaching picture also:


Just after writing this message, I found out that the IC MPPK 8794 is MPS MP8794 - https://www.alldatasheet.es/datashee...ND/MP8794.html

I've tried injecting voltage to the output of the inductor and it looks that there's no short/leakage, it's consuming 1 amp and the ARM CPU in the board is getting some heat (around 35ºC) but in uniform way, not just a real hot spot like when a CPU is shorted.

Not sure how to continue from here apart from replacing burned components once I know which they are. What would you do now?

Thanks

[lotas]

If the discharge went through the HDMI port (if a receiver, satellite tuner, etc. was connected to it), you need to check the signal lines (there are 8 of them). What resistance do they have relative to ground and where do they go to, either to the main processor or to the HDMI hub? What voltage did you apply to the choke? It should probably be 0.9 - 1.2 V, which is the processor core voltage. If you applied more, the processor is likely dead, unless it was killed by lightning beforehand.

F2 - EDZTE616.8B (Zener Diode)

[lotas]

XR-xxA95K IC811 0.8V POWER GPU