Vizio Plasma P50HDM Posterized & washed out color and flicker

[Morebass]

Vizio Plasma TV
Model# - P50HDM
MFR date: 6/2005
Screen: LG PDP50X3002142.ASLGA AB

I recently acquired this tv and after initial startup the picture appeared washed out, posterized and grainy. I visually inspected all caps and none appeared bad. Onboard fuses (2) checked good. After plugging the tv back in the picture now appears to have developed a flicker. Problem was the same fed through HDMI or analog. Did a factory reset with no change.
With DMM I probed the following:
Z bias: 98v
Vsc: 113v
Vy: 125v
Any suggestions?
Morebass

[capkid]

Re: Vizio Plasma P50HDM Posterized & washed out color and flicker

Your -Vy looks off; it should be somewhere around -200V. Check your panel label for accuracy. How are your VS and VA voltages?

[Morebass]

Re: Vizio Plasma P50HDM Posterized & washed out color and flicker

Ok, Seems my DMM batteries were dying so some of these readings were off.
Now my readings are:
Z bias: 98.9v
Vsc: -108v
Vy: -185v
Vs: 187.0
Vy:59.1
I do see what appears to be a Vs adjustment trim pot that's labeled "Vs-adj VR201" on the power supply board. Not sure if the 201 is a target voltage. I don't see any other labeled voltages for Vs and -Vy on the board I checked those voltages.

Morebass

[capkid]

Re: Vizio Plasma P50HDM Posterized & washed out color and flicker

Voltage specifications are on a label on the back of the panel. The label should be near the top of the panel - post a pic.

[Morebass]

Re: Vizio Plasma P50HDM Posterized & washed out color and flicker

OK, I see it. Posting pics.

[capkid]

Re: Vizio Plasma P50HDM Posterized & washed out color and flicker

Ok, it looks like your voltages are off or need to be remeasured:

Z bias: 98.9v - should be 100V
Vsc: -108v - should be 115V <--reverse polarity of probes
Vy: -185v - should be -200V
Vs: 187.0 - should be 196V
VA:59.1 - should be 60V

I'd SLOWLY adjust the VS to 196V first to see what kind of difference it makes.

[Morebass]

Re: Vizio Plasma P50HDM Posterized & washed out color and flicker

I adjusted the Vs from 185V to 196V and the Z bias from 98V to 100V. That appeared to eliminate the flicker but not the bad image. I attempted to adjust the Vy and Vsc with trim pots but couldn't get both dialed in to suggested voltages. I did adjust these while viewing and it appears to change contrast and brightness but the grainy posterized image didn't improve. I'm posting a pic of the board that I adjusted voltages and the TV image so you might have a better idea of what I'm adjusting and what the image appears as on the screen.
Appreciate the help and prompt reply.

Morebass

[capkid]

Re: Vizio Plasma P50HDM Posterized & washed out color and flicker

What are your current VSC and -Vy readings? You more than likely have a bad Y-Sus. What tends to fail on this Y-Sus is one of the large ICs under the heat sinks. The ICs usually fail catastrophically, where a Y-Sus fuse is blown and the picture is no longer visible.

http://blog.coppelltvrepair.com/2010...71qyh039a.html

I don't want to get to far ahead, but here's a repair option: http://www.ebay.com/itm/Sustain-6871...item255d4e1b2d

[Morebass]

Re: Vizio Plasma P50HDM Posterized & washed out color and flicker

OK, I was able to adjust the Vsc to 115v by turning the VSET_DN trim all the way down (counterclockwise) and turning the RAMP_UP all the way up. Turning these trims had mostly no effect on the -Vy (-185 to -189). Turning the VSET_UP either way had no effect on either Vsc or -Vy. Visually I don't see any evidence of an IC failure and all fuses I could see checked good. It appears the Y-Sus fails on these TVs so I should probably pull the board out and remove the heat sinks for better inspection. I don't have a problem sending this board in for repair if that's what is wrong with it... hoping it's not the screen that's bad.

Morebass