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Plasma TV Artifacting, Any Ideas As To Cause? Service Manual Attached

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iamdarkyoshi:
--Shit, my bad, meant to post in repair. Stupid fat fingers on a tiny touchscreen  :-//

First off, Panasonic TH-42PZ700U service manual: https://drive.google.com/file/d/1WT0pcLUll_75PJjsLaqB6FppEnmZklDa/view?usp=drivesdk

So I got this poor old TV off craigslist for free, didn't power up. Looked online and the common issue was the 150C thermal fuse in one of the transformers tripping. Ouch.

Once I fixed that, I got it working, and noticed some visual artifacts with my laptop plugged in. I'm no stranger to seeing these, but I figured I'd try setting all the voltages outlined in the service manual after I found a link online where someone fixed artifacts and sparkly pixels by cranking VSCAN /VSCN.  Page 33 ish in the attached service manual

I set voltages to what the service manual asked for, and my wii's start menu no longer had a yellow splotch at the bottom.

I did everything except the Initialization Pulse Adjust section. I couldn't find my scope probes.

But I've really just "shifted" what colour/brightness levels the artifacts show up. Here's a video outlining the worst of them:

https://youtu.be/Q1yFwZAGnss

I know this is just a tired old TV, but is there anything that can be done to correct it? That isn't a large steel weight on the end of a stick? This plasma has great video inputs for my older game consoles, something my new TV totally lacks.

drussell:
Could well be a damaged panel if the splotch never changes....

Does running a few cycles of the wipe function make any effect on the splotch?

If it improves, you could also try running random pixel noise (like old-style analog snow) at high brightness for a couple hours.  Sometimes that can be faster and easier than running many wipe cycles manually.

It is weird that it appears to go away at certain brightness levels, etc.

iamdarkyoshi:

--- Quote from: drussell on April 06, 2020, 07:42:26 am ---Could well be a damaged panel if the splotch never changes....

Does running a few cycles of the wipe function make any effect on the splotch?

If it improves, you could also try running random pixel noise (like old-style analog snow) at high brightness for a couple hours.  Sometimes that can be faster and easier than running many wipe cycles manually.

It is weird that it appears to go away at certain brightness levels, etc.

--- End quote ---

The splotch only appears on very certain colours. I played 2 hours of mario kart on it before I even spotted anything.
I took some photos but you can't even see it past the moire pattern...

Since the splotch is in the middle and the middle is the farthest from the driver connections, maybe it's low voltage related in some way? Every single aged plasma I've seen shows this in some way, where a very specific colour shows up as another one, a bit like failing graphics videoram on a PC graphics card

Shock:
Unrelated to the repair, it's not worth messing around with. Sell it and hunt around for some LED backlit TVs to repair while the Plasma is still worth something. A lot of people are in love with their Plasmas but it's like compact florescent lighting vs LED lighting, it's a technology we don't need back.

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