Plasma turns on, but shows no picture

[tom66]

Re: Plasma turns on, but shows no picture

Yrr+Yfr are on the Y-main.
You may want to increase/decrease some of the voltages by a maximum of 5V (Vs) or 15V (-Vsc/Vset/Ve). Do not adjust Va, ever!

[Daysleeper]

Re: Plasma turns on, but shows no picture

Found them on the y-main, but didn't change anything.

I lowered all of them VS, Vset, Vscan, Ve (and Va) cause they were all to high. But they all raised the voltages automatically from all alone (10 -20v higher). So turning the screws did not work at all plus I can't turn them any further.

The flicker is not there when I have connected the PS3 but I have some disortions on the bottom of the screen (colored, moving pixels). It got worse, when I altered Va, so i turned it back... But still this "noise"...

Did I break something when I altered Va??

[tom66]

Re: Plasma turns on, but shows no picture

What I should have said is do not increase Va. Dropping it should have no negative effect but in general you never need to touch it. High Va can kill the plasma panel making the TV an expensive paperweight. I do not trust your multimeter or perhaps you move the potentiometer when you stop adjusting? Tried using a plastic screwdriver instead?

[Daysleeper]

Re: Plasma turns on, but shows no picture

Actually I started to mistrust it either. I now unplugged the Y-Main and X-Main and it measures much lower values...

Changed the battery of my multimeter. Now it gives me the correct values. The flicker is almost gone.

Unfortunately the two small areas of noisy (yellow) pixels remain. Though they are only visable on light blue background. When the background color changes, they're completely gone.

[tom66]

Re: Plasma turns on, but shows no picture

Would you describe the noise as POSITIVE (that is pixels are lighting up when they should not) or NEGATIVE (the pixels are going dark when they should be lit up?)

[Daysleeper]

Re: Plasma turns on, but shows no picture

Well, positive then I guess then. They just jave the wrong color, yellow instead of light blue. On dark blue background or black for example they're not visible at all.

They seem to go on and off very quickly but basically staying in the same place.

[tom66]

Re: Plasma turns on, but shows no picture

OK, in which case, you will need to tweak, in order:

Vset (decrease by up to 10V)
Yfr (rotate)
-Vsc (increase [make more positive] by up to 10V)

Do each in turn, and play around with combinations until the picture improves.

[Daysleeper]

Re: Plasma turns on, but shows no picture

I better ask. What do you mean by Yfr (rotate)? 180° or just try it out?

[tom66]

Re: Plasma turns on, but shows no picture

Just try it and watch the screen while adjusting it. Marking the original factory position may be a good idea. If you get more misfires go the other way.

[Daysleeper]

Re: Plasma turns on, but shows no picture

Doesn't seem to have any effect on it all

[tom66]

Re: Plasma turns on, but shows no picture

Did you only adjust Yfr? Or all three?

[Daysleeper]

Re: Plasma turns on, but shows no picture

First I lowered Vset from 190 to 180 and watched if anything changed. Then I turned YFR. Then I set Vscan from -190 to -180, watched, turned YFR. Nothing. Then Vset back to 190, once more YFR, nothing.

I suppose it's YFR cause it's not labeled. Turning it up very high produces lot's of noise. Still think it's the right one. The only other screw on the board is labeled YRR.

Gotta run now. Will give it another try when I'm back home, but I really don't think it'll work.

[tom66]

Re: Plasma turns on, but shows no picture

You may want to try Yrr and lowering Vs for really bad sparklies/misfires (less of a science, more of a "try it and see")

[Daysleeper]

Re: Plasma turns on, but shows no picture

There is not much, that I could lower, since most screws are already very close to the left. Turning Yrr and Yfr doesn't let even one of those pixels vanish. No effect on them.

Playing a game I noticed them in the upper area around faces when there's movement on screen. Not very annoying but noticeable...

[tom66]

Re: Plasma turns on, but shows no picture

You can try both directions -- just back off if the panel goes wacky (too bright or dark.)

[Daysleeper]

Re: Plasma turns on, but shows no picture

I did try both directions but most screws can basically only be turned right, turning left they physically hit their "limit" and can't be turned any further.

So all I can do is increasing (turning right). In the case of Vfr the picture goes very noisy at some point.

Changing the menu-options for contrast, brightness, saturation, etc. causes those pixel areas to change their position on screen, but I can't make them go

[Daysleeper]

Re: Plasma turns on, but shows no picture

There is actually a third screw on some kind of extra-board, labeled YR5901 (the other both are YR5000 and Y5001). I didn't touch it yet, since I don't know what it does. Do you think I should also try this screw?

[tom66]

Re: Plasma turns on, but shows no picture

That may be Vset or -Vsc.

[Daysleeper]

Re: Plasma turns on, but shows no picture

So, I better leave it alone.

Since the menu-options have an effect on the "pixel-swarms" I came to thinking that the mainboard might be the reason.

I read an article by you bout some selftest for the controle board, but I don't know the jumper points for my board. Would you have a look?

I know it's a very bad photo, but maybe something looks familiar...

[tom66]

Re: Plasma turns on, but shows no picture

The problem isn't likely to be on the main board. The plasma panel on these older Samsung & LG based TVs is prone to getting maldischarge due to ageing of the panel. This can often be corrected by increasing or decreasing various voltages, or by adjusting the timings (Yrr & Yfr.)

Self test see here: https://www.badcaps.net/forum/showthread.php?t=26790