Samsung Plasma Color Snow

[craigc15]

I am attempting to repair a Samsung Plasma TV. I have already replaced a few bulging caps on the PS and Z-Sus boards. I have checked all the electrolytic caps on the PS, Y and Z-sus boards with a home-made ESR tester that I believe works, and they all test good (I removed most to insure no parallel reading effects).
The TV fires up, but when it first comes on, there is intense color snow, as shown in the attached picture. The snow fades as time elapses, but never goes completely away.
Any help would be greatly appreciated.
Thanks!
Craig

[tom66]

Re: Samsung Plasma Color Snow

Hmm, could be a main board, digital (main logic) board or Y-main issue. Have you checked Vset and Ve? Also, what is the model of this TV?

See here for a self test which can rule out a Samsung main board. https://www.badcaps.net/forum/showpo...61&postcount=2

[craigc15]

Re: Samsung Plasma Color Snow

Thanks for the quick reply.
It's a Samsung model HP-S4253.
Vset and Ve, as well as the other voltages on the label are "close".
I ran the self-test and it ran fine. The display was "discolored".

Next?

Thanks again!

[tom66]

Re: Samsung Plasma Color Snow

I would suspect the control board, which is the board that has the self test function.

[craigc15]

Re: Samsung Plasma Color Snow

I forgot to mention that I also replaced a shorted MOSFET on the Z-Sus board.

[tom66]

Re: Samsung Plasma Color Snow

Before you replace anything else, try adjusting Yrr/Yfr on the Y-main.

[craigc15]

Re: Samsung Plasma Color Snow

I tried, but no difference.
It seems the red is most intense, followed by green.
It's really bad when the TV first comes on, but about 10 minutes later it's not too bad. The picture is fairly good, just a lot of colored snow.
Still recommend the controller board?

Thanks much!

[tom66]

Re: Samsung Plasma Color Snow

Perhaps not. It does seem simply like overdiffusion, too many pixels sticking. Odd colour balance is a clue, too. I would check Vset, Vscan, Ve, and Va, match them to the panel sticker. If not it could be a control board fault I suppose.

[craigc15]

Re: Samsung Plasma Color Snow

I did set all those voltages according to the sticker.
I guess I'll look for a new controller board.
I'll let you know how it works.
Thanks!

[craigc15]

Re: Samsung Plasma Color Snow

Before buying any more boards and playing poke and hope, I was able to determine that the Yrr pot on the Y-Sus board was dirty. Now that I've cleaned it, the initial "warm-up" problem has gone away. The only issue remaining now is colored snow, especially in the dark areas of the image.
I found a YouTube video claiming that this problem was due to bad cap(s) in the 5V section of the PS. I checked them before, but I'm going to go back and tack in some more capacitance to see if that works.

Any other thoughts from anyone?

[tom66]

Re: Samsung Plasma Color Snow

For coloured random sparklies just try tweaking Yrr and Yfr to taste.

[craigc15]

Re: Samsung Plasma Color Snow

It's more like a color blizzard.
Those adjustments don't do it.
I'm going to replace the Yrr pot and see if that gets me anywhere.
I tried caps on 5.3v and Vg (15V) with no success.

[craigc15]

Re: Samsung Plasma Color Snow

Well, I replaced the Yrr pot and while I was tweaking the pot next to the Yrr pot, not the Yfr pot, the Switcher chip for Va on the PS popped.

I had actually stopped adjusting the pot when it blew.

Do you think they're related, or just a coincidence? Seems strange.

Any thoughts on why it popped?

Thanks!

[craigc15]

Re: Samsung Plasma Color Snow

Well, I'm about to give up on this TV. I hate working on plasmas.
I replaced the blown MosFET (and a zener diode) on the PS and it's back on, but still can't get rid of the RGB snow. I've searched the internet pretty thoroughly and tried everything that others tried with no luck.
The picture is beautiful, except for the snow.
Any final suggestions?

Thanks!

Craig

[tom66]

Re: Samsung Plasma Color Snow

Check ALL voltages are to spec against the label.
Try and borrow a scope to test the Y-main and X-main output.
Consider a control board/main board fault.

[cadiman]

Re: Samsung Plasma Color Snow

When you bring up the tv menus what do they look like? are they ok?

[craigc15]

Re: Samsung Plasma Color Snow

Still snow with the menu.

I have set all the voltages according to the label.

I have a scope, but how do I know if the waveforms are correct?
The service manual doesn't show them.

Would they be the same as any plasma TV? I know the Vizio P50HDM manual has images of the waveforms. Should I just go by that?

Thanks!

Craig

[luchoserrucho]

Re: Samsung Plasma Color Snow

I have the same issue with my samsung pn64d8000ffxza. Checked the voltages and all of them are ok, did the software upgrade and nothing seems to work. I keep having the same red screen with red snow. Can anyone share some light on this issue thanks!