Questions about testing VA/VS voltages on plasma panels.

[Shinju]

OK, so I have done quite a few plasma repairs and very rarely have to adjust VA/VS Voltages.

Taking for example this G15 I just did. the panel stickers were VS 199/ VE 135.



Are these voltages set with a full white screen VIVID torch mode 100 bright/contrast ect.

The Voltages at black screen were below what panel spec, are these voltages supposed to be 199/135 at all times? When I did the white screen vivid setting per service manual testing suggestions the voltages were with in spec and occasionally they would go just a tiny bit higher then the highest spec then go right back down.

Or are these voltages variable depending on panel action? I know each PDP manufacture seems to be different I am trying to get more of a solid answer on how these voltages are suppose to work.

How do you all set/test these voltages.

trying to learn more!

[tom66]

Re: Questions about testing VA/VS voltages on plasma panels.

The power supply will have a load regulation figure, this will define how well it will keep the set point as the picture varies. A few volts is usually acceptable.

The Vs is determined by the panel gas pressure and on the older panels is typically somewhat variable from panel to panel within the same generation. In newer panels the technology has improved to the point that most require no different adjustment at all. The Va is determined by the panel technology including the spacing between the address and sustain electrodes and is typically fixed for any given panel technology. Excessively high Va can damage the plasma panel TCPs rendering the panel dead. The Ve is also determined by the panel gas pressure and is much more variable, it determines the erase/initialise bias energy for the common electrode side of the panel.

[Shinju]

Re: Questions about testing VA/VS voltages on plasma panels.

What would you consider excessive voltages? 2-5volts over or 5-10 volts over spec?

[tom66]

Re: Questions about testing VA/VS voltages on plasma panels.

Va: +10% over sticker or +5V whichever lower
Vs: +15% over sticker or +20V whichever lower

Ve << Vs at all times

[Shinju]

Re: Questions about testing VA/VS voltages on plasma panels.

Bumping this back up.

I just found out my DMM was off due to a bad probe, I am currently using a high end fluke auto adjusting DMM.

This 450A2D I set with the old DMM and the other day I noticed in dynamic mode there was purple splotches for a few seconds so I pulled the back off and check the VS and it was pretty low 198 panel spec 207.


So at 207 I am back to seeing this rainbow line about 2-3 pixels thick going horizontal from right to the middle of the screen (more prominate on whites) If I turn down the vs to 203-202 it's gone.

Is my Ymain going belly up or is the buffer going bad?

VA and VSCAN are spot on in spec.

[tom66]

Re: Questions about testing VA/VS voltages on plasma panels.

Hmm, line only visible on full white? Could be Y-buffer showing breakdown, maybe regulation ckt is not good at high Vs for Vscan side...

[Shinju]

Re: Questions about testing VA/VS voltages on plasma panels.

Yeah its strange, if I turn it up past the 207 the anomaly gets large (green/red misfire) at the top right of the screen, if I turn it down to 201-202 its gone completely. I have it right at 204.2 and its gone unless I run the Scrolling wipe. And then its hardly visible at all I only see because I know its there the wife couldn't tell at all at 204.

I am just wondering if the Ysus did suffer damage when the Xmain cooked itself.

The panel seems to run fine at 204 on Dynamic 100 con 10 cell, but I never EVER watch it like that I have it on Movie 77 con 6 cell and 34 bright and it looks great for being a super budget panel.