Dead Vestel 17IPS71 power board

[FullnameJon]

Re: Dead Vestel 17IPS71 power board

If I test the DC output with the mainboard connected, the voltages drop even faster than before. Measured HV from FAN6300A to 320V and VDD peaks at 20.68V but dies almost directly then goes back up and repeats.

[budm]

Re: Dead Vestel 17IPS71 power board

I did not read the latest thread in details yet to see what is going on with FullnameJon's board.
Can we see good clear straight shots of the whole bottom side of your board?
I also attach the Vestel training manual for 17IPS71 for reference.

[FullnameJon]

Re: Dead Vestel 17IPS71 power board

I've tested another mosfet and optocoupler, no difference. U202 or something before it keeps resetting it seems.

[budm]

Re: Dead Vestel 17IPS71 power board

If I test the DC output with the mainboard connected, the voltages drop even faster than before. Measured HV from FAN6300A to 320V and VDD peaks at 20.68V but dies almost directly then goes back up and repeats.

Are you still getting unstable output if main board is not connected?

[FullnameJon]

Re: Dead Vestel 17IPS71 power board

Yes sir

[budm]

Re: Dead Vestel 17IPS71 power board

OK, try to locate the lytics caps as shown in the solid red boxes I marked, then heat them up with hair dry for few minutes then power up the board by itself to see if the Voltage will become stable or not.
BTW, you did check all the power diodes in the cold side correct since I see some of the legs had to be soldered back in place, correct?

[FullnameJon]

Re: Dead Vestel 17IPS71 power board

I have checked those. I will check the caps as soon as I can.

[FullnameJon]

Re: Dead Vestel 17IPS71 power board

Ok, I can't even find the marking for C295. C302 isn't populated. C296 read 95.76uF and 0.40ohm.
C64 110nF no ESR reading.
C73/C33 (double marking, same spot) is a 100uF 35V that read 105.2uF 0.34ohm.

[FullnameJon]

Re: Dead Vestel 17IPS71 power board

Forgot to say that it made no difference if I heated those capacitors up. Still resets.

[robert1000]

Re: Dead Vestel 17IPS71 power board

Forgot to say that it made no difference if I heated those capacitors up. Still resets.

Hello, how did you fix it? Please reply. Thank you!

[cheeky2]

5 years later from the previous post! It's unlikely you will get an answer. I suggest you create a new post with your issues or start reading through some of the threads to check for yourself where to start checking