Samsung 42 inch problem(s)

[dmak170]

Hi, I'm hoping someone can help me out.

I have a Samsung 42 inch plasma (Model PN42B430P2D) and I have sound, the problem is the picture.

The tv turns on fine, but it seems after a while....

1. The top quarter of the screen goes black. And..

2. The bottom portion that does turn on looks like a "lava lamp"

I've checked Va and Vs voltages, all fuses, and for obvious swollen caps, all seem fine. I've also tried looking for shorts on the Y buffer board with no luck, obviously I could have missed something.

My question would be, could a bad Y buffer board cause the "lava lamp" symptom? As I'm fairly certain it is the cause of the black screen. (The two top most chip are probably failing)

or...

because the tv turns on for a bit, could this be a cap on its way out? As the temp increases, it fails? Or could it be another component?

Thanks in advance.

[steviewonder]

Re: Samsung 42 inch problem(s)

Interesting description,for sure!
My guess is the upper buffer is ok,and would suggest it's the timing/control board at fault,Try cooling it down when the fault appears with freezer spray or compressed air.worthwile also jumping the test pins on this pcb to provide a test screen,details in the service manual,this really only eliminates the motherboard though,in practice!

[steviewonder]

Re: Samsung 42 inch problem(s)

Having said all that though,I have seen some wonderful and odd issues with ysus panels on samsungs too..A picture of the actual fault would help the diagnosis though...

[zacheriaj]

Re: Samsung 42 inch problem(s)

Interesting description,for sure!
My guess is the upper buffer is ok,and would suggest it's the timing/control board at fault,Try cooling it down when the fault appears with freezer spray or compressed air.worthwile also jumping the test pins on this pcb to provide a test screen,details in the service manual,this really only eliminates the motherboard though,in practice!

steviewonder has a great point. A lot of times when a single SMD component fails under higher heat, a can of freeze spray or compressed air is a great way to diagnose quickly. If using something such as computer "duster", hold the can upside down to turn it into freeze spray.

[dmak170]

Re: Samsung 42 inch problem(s)

Wow, I never would have thought of that! When I get a chance, I'll give that a try!

I was under the impression that as a new member I wouldn't be able to post pictures, but I'll try anyway!

Thanks a lot!!

[steviewonder]

Re: Samsung 42 inch problem(s)

you're welcome!
what's obvious to one isn't always obvious to another,and vice-versa!! Good luck,I don't think you will struggle with it now,somehow!

[dmak170]

Re: Samsung 42 inch problem(s)

So, I finally had time to look at the TV again, and when I plugged it in and turned it on, it was immediately faulty (same as before top quarter black, while the rest has a "lava" lamp look, not showing any picture {Tv menu or otherwise}) I gave the freeze spray method a try anyway, (albeit knowing that it probably isn't a heat issue since it was just turned on) without any luck.

I've attached a picture of the set, if anyone has any other ideas, I'd be very great full. Thanks.