Need help with Samsung HPR4272

[adam699]

Hello,

So I got the TV with no picture but sound. After some investigating I figured out that the lower Y buffer shorted and burned out the lj92-01200a Y-sus board.
I changed the IPM, a shorted Mosfet, two resistors and one diode and the faulty buffer board as per other threads on the subject and got up to this point and now I'm stuck seeking advice.

The voltages specified on plasma panel all check out when probing test points.

I get a distorted picture as on the photo. The menu appears way better than rest.

Please advise what to look at next.

[adam699]

Re: Need help with Samsung HPR4272

Picture #2

[adam699]

Re: Need help with Samsung HPR4272

Picture #3

[kasfamily]

Re: Need help with Samsung HPR4272

What values Vs,Va,Vset,Ve,Vscan ?

[ERICSSON89]

Re: Need help with Samsung HPR4272

upload pictures of ur PSU both front and back, mainboard and TCON board. your TCON board might be the culprit.

[mmartell]

Re: Need help with Samsung HPR4272

Try unplugging xmain and see if pic still looks the same.

[mmartell]

Re: Need help with Samsung HPR4272

upload pictures of ur PSU both front and back, mainboard and TCON board. your TCON board might be the culprit.

According to the first post this is a plasma not an lcd.

[adam699]

Re: Need help with Samsung HPR4272

What values Vs,Va,Vset,Ve,Vscan ?

The sticker on the panel says:
Va: 70
Vsc: -190
Vs: 205
Ve: 82
VSet: 195

When i probe it:
Vs: 191
Va: 68
Vset: 196
Ve: 82
Vscan: -191

[adam699]

Re: Need help with Samsung HPR4272

Try unplugging xmain and see if pic still looks the same.

This is what I get when I unplug the xmain

[mmartell]

Re: Need help with Samsung HPR4272

To my untrained eye it still looks like a xmain problem. Try measuring Vbias on the xmain.

[adam699]

Re: Need help with Samsung HPR4272

To my untrained eye it still looks like a xmain problem. Try measuring Vbias on the xmain.

I don't see a test point for Vbias. How do I measure that?

Also the picture looks more normal when there is no signal.

[tom66]

Re: Need help with Samsung HPR4272

Vbias = Vzbias, same as Ve.

It's hard to tell what board is at fault... do you have an oscilloscope or can you borrow one? The Y-main and X-main output waveforms can be checked, if you have one available.

[adam699]

Re: Need help with Samsung HPR4272

Vbias = Vzbias, same as Ve.

It's hard to tell what board is at fault... do you have an oscilloscope or can you borrow one? The Y-main and X-main output waveforms can be checked, if you have one available.

Like an old school osciloscope? My father might have one, I'll check if he does.

Is there some PC based osciloscope software I could use?

[tom66]

Re: Need help with Samsung HPR4272

I wouldn't use a PC scope for a plasma panel, the sustain voltage is too high for most of them (peak 400V amplitude!)

If you can borrow a scope that would help greatly - try to get a 10X probe with it too...

[adam699]

Re: Need help with Samsung HPR4272

No go on the scope. I don't really have anyone that I could borrow it from. What am I looking for? I searched on ebay but it seems like there might be different ones for different pourpose.

[adam699]

Re: Need help with Samsung HPR4272

Well, I risked it and ordered a working Ysus board and all is well now in case anyone cares