Vestel 17PW01-4 PS board stuck in standby

[Nevillet]

Re: Vestel 17PW01-4 PS board stuck in standby

It's a 1uF 63v but assume it'll be ok.

No change.

[dick_barton]

Re: Vestel 17PW01-4 PS board stuck in standby

IC500 FAN7711
1 - VDD 14.93v
2 - RT 0.001v
3 - CPH 0.001v
4 - GND
5 - LO 0.542v
6 - VS 13.18v
7 - HO 13.57v
8 - VB 14.91v

The data sheet for FAN7711 says that normal operation is when CPH voltage reaches 7V.
After changing the capacitor are the FAN7711 voltages as you gave earlier shown above.

[Nevillet]

Re: Vestel 17PW01-4 PS board stuck in standby

I'm away now till tomorrow PM. Many thanks so far..

But before I go:

IC500 FAN7711
1 - VDD 14.73v
2 - RT 1.762v
3 - CPH 1.3531v
4 - GND
5 - LO 0.000v
6 - VS 13.66v
7 - HO 13.67v
8 - VB 14.93v

[Nevillet]

Re: Vestel 17PW01-4 PS board stuck in standby

I'm back now. I feel like we have given this power supply a good effort and it's probably now the time to throw in the towel.. Are we agreed?

[dick_barton]

Re: Vestel 17PW01-4 PS board stuck in standby

Can you change IC806 (FAN7711) as the last resort to rule it out as being faulty?
With the diode in backwards then the 12V supply would have appeared to be almost a short circuit.
You've ruled out the two mosfets as being damaged and the supply voltages for the FAN7711 looks good but it cannot be operating since you are not seeing the 12V on the secondary side of the transformer it's driving.

[Nevillet]

Re: Vestel 17PW01-4 PS board stuck in standby

I don't have a FAN7711 in stock.

It's not stocked by CPC/Farnell and RS have it but as a SMD.

There's one on eBay for £3.09 delivered which seems a bit steep but It might be worth a punt.

Now ordered.

[dick_barton]

Re: Vestel 17PW01-4 PS board stuck in standby

Good luck. Can't thnk of any more moves. Keep that smd capacitor (11.19uF) in case it needs to go back in. What was it's ESR

[Nevillet]

Re: Vestel 17PW01-4 PS board stuck in standby

The C928 cap measured 9.1uF, ESR 0.00

I'll report back when the chip turns up.

[Nevillet]

Re: Vestel 17PW01-4 PS board stuck in standby

The new FAN7711 arrived and replaced the original but unfortunately no changes were seen.

[nomoresonys]

Re: Vestel 17PW01-4 PS board stuck in standby

I think we crossed posts..

D909 was backwards??? I can't quite understand that because to test them I cut one leg rather than desolder the whole diode..

Anyway, it's now round the correct way. Out of circuit the drop was 0.135. (the same as the other 2)

Voltage across C970 is 0.000v

.

[dick_barton]

Re: Vestel 17PW01-4 PS board stuck in standby

That's a pity. Hopefully someone else can offer further assistance and spot what I have missed.

[Nevillet]

Re: Vestel 17PW01-4 PS board stuck in standby

With your help, I've learnt a lot about this board and power supply boards in general. This particular TV had a negative outcome but I'm not overly disappointed. I'll salvage the boards and bin the rest. Sincere thanks.