Samsung PS42C96HD no picture/sound OK

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

Ok so what could be bad? What next to check. Is the Y-main problem or something wich control it?

[tom66]

Re: Samsung PS42C96HD no picture/sound OK

I think the Y-main is good, but something is up with the control board or main board.

Here, I highlighted a test point on X-main. Please check this too. The waveform will be different. Capture at 2ms and 20ms/div.

I'm still confused why doing the 3-4 jump doesn't make the panel run test patterns, as it simply looks like the control board is receiving no video.

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

Yes i have same feeling... I did unpluged LVDS shorted 3-4 fired TV up and nothing changed.
I will take X-main waveform.

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

ok i have new pictures... X-MAIN test point

[tom66]

Re: Samsung PS42C96HD no picture/sound OK

Again the waveform is completely wrong - so I suspect the control board.

Can you see if the X-main waveform changes when the Y-main is unplugged (power and control?)

And then measure on the Y-main again with the X-main unplugged.

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

With Y-main unpluged is X-main waveform completely the same no change.
And with X-main unpluged is Y-main waveform same too no change.

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

So how can I check t-con? there is some test point.

[tom66]

Re: Samsung PS42C96HD no picture/sound OK

I am thinking control board right now. We can also check the main board. For that I will need a close-up shot of the LVDS connector on the control board.

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

ok i have here motherboard near LVDS and T-con.

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

Simple question all these measrements was with no signal.. no input pluged in... but that doesnt matter i guess.

[tom66]

Re: Samsung PS42C96HD no picture/sound OK

Shouldn't matter. TV should still display "NO SIGNAL" with no input.

[tom66]

Re: Samsung PS42C96HD no picture/sound OK

I've highlighted some points. Test here for any waveforms with LVDS connected.

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

ok that will be dificult to test but i will try and do you know what is V-togg test point in the right top? and what should be here

[tom66]

Re: Samsung PS42C96HD no picture/sound OK

I don't know what V-togg is.

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

ok i tried test that points but all looks similar and its some noise only here... or is that right signal?

[tom66]

Re: Samsung PS42C96HD no picture/sound OK

No, the main board is sending no signal. I guess the self-test doesn't work on this model or the control board also has a fault. Either way, something on the main board looks to be faulty.

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

ok can i test video output from the motherboard?

[tom66]

Re: Samsung PS42C96HD no picture/sound OK

There are some crystal oscillators on the main board which could be bad, as well as some regulators. Checking those points on the control board shows the main board is not sending the right signal.

[godzzila]

Re: Samsung PS42C96HD no picture/sound OK

I checked oscillators as well as vregs at first time.. all looks good.
TV stoped working from day to day without any signs of getting worse.

[tom66]

Re: Samsung PS42C96HD no picture/sound OK

I would suggest a main board swap, although, there are schematics available (for Q96, which I believe is very similar.)
http://www.tgohome.com/ServiceManual...h=Submit+Query