Finlux 32FLD760P with Vestel 17PW20.v1

[budm]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

I did download your manual from the link on post 102 and I see 17pw15 on the diagram.
Vestel_17MB22_Finlux_32FLD760_[SM].pdf
I got page error on the link of post 120.
http://www.tgohome.com/ServiceManual..._17PW20v1_PSU_[SCH].pdf

[tom66]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

The forum doesn't like [SCH] in URL.

Which is why I like using these links instead:
http://www.tgohome.com/ServiceManual...&Search=Submit

17PW15-9 is older version of 17PW20... it was the original design and they added a few features and cost savings.

[Serkai]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

It's awful, such a mess, and the PFC controller is apparently a MOSFET, I guess that was a readily available footprint and they were too lazy to change it...

Then perhaps I have a faulty MOSFET? I did see some in the common repair kits you can buy.

Couldn't sleep, too much vestel in my head making holes in important places.

Edit. By the way, the tv works fine as long as I don't put the back cover on and keep it cool enough. Is it because it needs less power when it's cold or something so my 21v barely makes it as enough?

[budm]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

OK, I looked at the SCH, with TV on, what DC voltage do you get at pin1 of IC828 (LM317) and the primary ground (negative leg of C881)? I believe it will be less than 5V at this condition.
And what is the input voltage feeding pin 3 of IC828 (LM317)? It should be around 18~20VDC.
That Q835 should be turn OFF by the OPTO IC811 (Photo transistor should be ON, if Q805 is ON. You can force off Q835 by shorting the Base to Emitter, this should cause the output at pin 2 of IC828 to put out the 12V as needed.

[tom66]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

This has been measured. Vcc is too low at 5V. VF_MAIN is about 12.5V, though that hasn't been measured under power.

[budm]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

Since the VF_Main is also from the same transformer for the 3.3V. Does he get the correct 3.3vstby and the 5VSTBY out put, he should also be able to find out if that Q835 is turn off. I expect VF Main to be higher. He should be able to turn off Q835 manually also.

[tom66]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

How did you calculate 18~20V? The controller IC can run from 12V to 20V.

[Serkai]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

Wow, woke up to some nice updates here. I'm getting a little confused though, what am I supposed to check, and in what order?

[budm]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

LM317 will need at least 18V or so at the input to give 12v out for the regulation head room to feed the PFC IC, the cap C801 (33UF 50V) at the VFMAIN is also rated at 50V, so it must be quite high.
So check the 5VSTBY and the 3.3stby. Then also check the C801 by replacing it.

[tom66]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

An LM317T's drop out is closer to 2V. Just wondered if you added a fudge-factor or something, because someone else on another forum said 18~20V.

[budm]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

The spec, typical diff between Vin-Vout is 3V for LM317, I myself will not use it that close without head room. He needs to find out why VFMAIN is only 12.5V.

[tom66]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

Heh, I use them to regulate 5V to 3.3V on my breadboards (naughty me... I guess), they work down to 4.7V (around 1.5V drop) but that is only at 100mA or so.

Well, we know the LM317T is regulating as it has 1.2V between out and adjust, so maybe that control transistor is leaky? Seems strange though, for such a device to fail would be unlikely, but never eliminate any possibility. If that transistor is removed, it could still work, but the PFC would run during standby (it would use more power.) I do not see this being a big issue though.

[budm]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

OK, on this power supply board, the STBY (PS_ON) is an active LO, when PS _ON goes LO, Q804 turns OFF, causes Q805 to turn on which turns on the LED inside OPTO IC811 which will turn on the Phototransistor, that will cause pin4 of the Opto IC811 to go LO. When Opto IC811 pin 4 goes LO, it will turn off Q835 which will cause the output of the LM317 to go up to 12V, in the standby mode, Q835 will bae on and cause the output of the LM317 to be at 1.2V hwich is not enough for the PFC IC 802 to run (the PFC IC will in the UV mode).
The PFC circuict IC 802 is kept off by two signals, one is the VCC2 at pin8, the second is the S2 (PIN3) which will shutdown of the 400V put goes too high, the senisng is done by Q823, Q824 PF_OFF signal.
So right now he neds to get the VFMAIN, VCC2 at the correct voltage first by checking or replacing C801 for the VFMAIN.

[tom66]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

The point I'm making is that out-adj was measured to be 1.2V, so the LM317T is regulating correctly at the voltage it is set to. But I don't know if that was measured in standby or not.

[budm]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

OK, the VFMAIN will be constant because it is generated from the standby power supply circuits. I hope he will start testing soon to tell me what he finds on the 3.3v stby an dthe 5vstby and the VFMAIN, all generated by the same transformer.
Also then the VCC2 must be measured when the TV is on, I hope to hear feedback soon.

[Serkai]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

The point I'm making is that out-adj was measured to be 1.2V, so the LM317T is regulating correctly at the voltage it is set to. But I don't know if that was measured in standby or not.

That was measured in ON mode with the tv showing a movie, if it makes any difference?

Oh and Bud, I'm not sure which ones are the standby 3.3v and 5v to check, I'm not really that good at locating what's what. But I'll see what I can find!

All the measuring I'm doing now is with the tv on, but if it needs to be standby, let me know and I'll see if I can figure it out! Thanks guys

[tom66]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

Standby 3.3V/5V are the only rails present when TV is in standby. Check them both in standby and when power is applied.

[Serkai]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

3.3v and 5.4v on standby. 3.35v and 5.5v when powered on. Does that help any? Slightly too high 5v right?

[tom66]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

Given it has a linear regulator, it's kind of suspicious, but shouldn't cause any major issues. What is the voltage at VF MAIN (C881)?

[Serkai]

Re: Finlux 32FLD760P with Vestel 17PW20.v1

C881, the small cap at the top of the big main cap? It reads 13.1v across.