Samsung PS42C96HD no picture/sound OK

[godzzila]

Hi i have here samsung plasma tv PS42C96HD with no picture but sound work ok as well as remote control (I can switch channels)

So i did usual checks not visible damage anywhere, all caps ok (ESR) etc.
Main voltages looks ok too.
Vs 205V
Va 63V
Vsc -190V
Ve 99V
ICs on Y-buffer looks ok no damage, no bulged caps. Checked also all the fuses bigger ones as well as small on Y,X boards.

In dark room (lights off) TV slightly glow, and slightly blinks after startup but no picture at all.

Also checked T-con, fuses ok voltages ok. Tried unplug LVDS cable and shorted pins 3-4 for test but nothing changed still no picture.

I really dont know what else I can try.. may be panel damaged? I am a newbie in plasmas I have also an oscilloscope but dont know what to check.

Thanks for any help.

[tom66]

Re: Samsung PS42C96HD no picture/sound OK

Try doing the tests indicated in this thread:
https://www.badcaps.net/forum/showpo...61&postcount=2

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

hi as you can read in first post I tried that
Tried unplug LVDS cable and shorted pins 3-4 for test but nothing changed still no picture.

[tom66]

Re: Samsung PS42C96HD no picture/sound OK

Sorry, missed that. The screen glows though?

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

yes in fully dark room its glow a little but show blackscreen only

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

So if its glow.. looks like the problem is sitting in Z board? So how can I test Z-sustain (x-main) board?
I measure here Ve: 99V that is ok what next I can do?
I tested all components for short or open but all looks good.

[tom66]

Re: Samsung PS42C96HD no picture/sound OK

Glowing but no image can indicate an address failure or control board issue.

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

Ok so how can I test a T-con board? I tried the self test pins 3-4 but nothing changed.
Can I test some points with and oscilloscope for some signal? That tells me if T-con is ok

[tom66]

Re: Samsung PS42C96HD no picture/sound OK

An oscilloscope is ideal. Can I get a picture of your control board? What is the maximum voltage it is rated for?

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

I will take a real picture tomorow but its this one:
http://i.ebayimg.com/t/Logic-board-LJ41-04780A-R1-5-from-Plasma-TV-Samsung-SPD-42Q72HD-/00/s/ODkyWDE2MDA=/$T2eC16Z,!ysE9sy0i3R0BQNQi3MdRg~~60_12.JPG

My oscilloscope is for 600V if it was the question.

And is it possible somehow to test address board too?

[tom66]

Re: Samsung PS42C96HD no picture/sound OK

Yes, I wanted to know the maximum scope voltage. You will also need 10X probe, for testing the Y-main and X-main boards.

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

yes i have probe with a switch to x10.

[tom66]

Re: Samsung PS42C96HD no picture/sound OK

OK, can I have a picture of the Y-main and X-main of your TV?

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

ok i have pictures

[tom66]

Re: Samsung PS42C96HD no picture/sound OK

Set scope to 10X, 2ms/div, 5V/div (equivalent to 50V/div).
Take picture of waveform measured at the lead I highlighted.

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

ok i have pictures.. first is as you said only 100V per div (x10 set on probe and oscilloscope too so its right)
second is stoped and inspected a little.. looks good isnt it?

[tom66]

Re: Samsung PS42C96HD no picture/sound OK

Was that on AC or DC coupling?
Can you try at 20ms/div.

Looks a little odd to me.

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

DC coupling i will post 20ms/div

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

There it is.

[tom66]

Re: Samsung PS42C96HD no picture/sound OK

Yes, something is definitely not right with that waveform.
The fields are all the same width.

Here is a representation of a 5-bit waveform (yours will be 8-bit):
http://w.pat.tc/WO2011111388A1fp.png