Vizio P50hdtv20a power supply issues

[eagle00799]

Hi everyone, I am trying to revive this plasma tv. When I plug it in the amber light comes on and when I turn it on the light turns green but I get no picture,no glow,no flash and sound is hard to say for sure since I cant tell which input I'm on.
When I turn it on i hear the clicks and the led light on the logic board light up with led2002 flashing then all 3 shut off and the led on the power supply flashes continuously. If i take the jumper off cn8010 the logic board will stay on but i only get 1.45v on Vs and Ve, I get 15v on Vg and 63v at Va. Any ideas if this is power supply,main or logic board? I can't see any bulged caps or any obvious problems.

[tw2005]

Re: Vizio P50hdtv20a power supply issues

Sounds like samsung boards? any pics.

If Samsung, check Y upper buffer and Ymain for short cct. 88n30w FETS on the ymain commonly short.


sounds like it's going into protection

[eagle00799]

Re: Vizio P50hdtv20a power supply issues

Well when I first got this tv I would get a flash on the screen so after removing the back I noticed a bulged cap on the Ysus and a fried chip on the upper buffer. After read some threads on this site it seemed that there would be multiple components shorted on the Ysus so I shipped the Ysus and both buffers off for repairs. I'm not sure what they did to the Ysus besides replace the 1 cap but I will check it like you said. I also had a bulged cap on the Zsus and figured it would mean more was wrong then the cap so I got a used board from ebay too.
I will see what I come up with after I check the fets for shorts and yes they are Samsung boards.

[tw2005]

Re: Vizio P50hdtv20a power supply issues

Oh, that sounds expensive. dare i say it but could be a dud repair. maybe put some clear shots of both buffers and ymain, top and bottom.

lower buffers usually survive. Did you get any warranty with the repair? Somone reputable ?

[tw2005]

Re: Vizio P50hdtv20a power supply issues

Tom's video on Samsung 50 with the same panel and drive boards. Might be helpful.

https://www.youtube.com/watch?v=25HT...tCVe9&index=14

[eagle00799]

Re: Vizio P50hdtv20a power supply issues

Itritek Solutions in San Jose,Ca did the repairs for $140 and I think you might be right on the dud repair job. There are 2 resistors that look burnt also that they didn't do anything with.
Whats the best way of testing these mosfets?
I will post pics tomorrow.

[tw2005]

Re: Vizio P50hdtv20a power supply issues

continuity mode, just check across any 2 legs all combinations, solid beep is dead. They're in parallel so if one is in cct short, the rest will test short too.

[eagle00799]

Re: Vizio P50hdtv20a power supply issues

I didn't find any shorted mosfets and I checked the resistors that looked burnt and they read the same at .003v and 5.0 ohms. does that sound right?

[tw2005]

Re: Vizio P50hdtv20a power supply issues

probably. are they burnt or maybe just the colour of them? what's the part nmbers on the board so i can have a look at SJ.

get anything out of the video? maybe check resistance at the power connector on the ymain.

Unfortunately my experience with these is limited to the symptoms I've described. All 3 I did were straight forward 88n30w fet replacements and a upper buffer.

I think in toms video he has one with other issues and shows how to check the buffer, but now you have a repaired/semi-repaired board makes it hard.

I assume the TV has never powered on since you got these back, yet before you said you had a brief flash so that at least suggests panel voltage came n briefly, now nothing.

did the PSU light come on before with the original boards?

It should be possible to isolate everything form the PSU and force it on to prove that.

I can't remember now, but if you disconnect the power to the ymain and disconnect the white ribbon to it as well, what happens or check vsus at the psu as you power on.

[eagle00799]

Re: Vizio P50hdtv20a power supply issues

I would get a brief flash at first then when I opened the back I noticed the bulged caps on both Ysus and Zsus and a burnt chip on upper buffer so I didn't power it on to see if the LED was flashing, Didn't want to damage anything else.
I disconnected the Ysus and ribbon and got the same results and checking the VS on start up gets 2.04v before dropping again.

[eagle00799]

Re: Vizio P50hdtv20a power supply issues

I unplugged the x board from the PS then powered the tv on, I then jumped 5v to the VS-ON pin and it would trip the PS LED1 light to flash constantly.
I was attemping to force the VS on and tried this with and without the Ysus and Zsus connected and it didn't make a difference. Does this sound like a power supply issue? and what component would I test?