Yellow discoloration on Panasonic 50" Plasma - VSUS option missing in service menu

[kca]

Hello all ~

Just got a Panasonic 50" plasma that has a yellowish discharge that only shows up when the screen is white or a light tan. Hockey games, commercials with primarily white backgrounds, etc ...

The Model # is TH-50PZ700U

It is HIGHLY noticeable. Needs fixing. So, I researched it, and found that I should be able to adjust the VSUS from Low to High in this Panny's service menu.

I got in there successfully, but the VSUS adjustment option is missing from the master list. I watched two videos on YouTube just now. One guy had the VSUS option in his list and the other did not.

If you look down the left-hand side of the service menu picture (see below) the term VSUS should appear in the list between OPTION and AGING (according to the video I viewed), ... but for some reason is missing.


Question, then, is .... Is there a way I can easily access this VSUS option in my service menu even though it is not initially appearing in the list?


I'm attaching a pic I took of the list itself as it appeared on my screen. Also attaching one that shows the # of hours on the set (a bit over 15,000).

[kca]

Re: Yellow discoloration on Panasonic 50" Plasma - VSUS option missing in service m

Now, here is a screenshot of the video I was referring to in Post #1.

You can clearly see the VSUS term placed right there between OPTION and AGING.


NOTE: I know I can probably make this adjustment manually if I take off the back cover to the set. And, I will do that if necessary. But I want to first simply change it from LOW to HIGH in the service menu and see what sort of change that causes. I've read where several folks had immediate success in getting rid of all or most of this yellow discharge / discoloration that is now plaguing the picture.

[kca]

Re: Yellow discoloration on Panasonic 50" Plasma - VSUS option missing in service m

A couple of pics from a hockey game that clearly illustrate the “yellow patching” problem. The yellow diffusion tends to follow the skaters around, but not always and not uniformly.

Does anyone know if Panasonic discontinued the VSUS adjust on the service menu at some point in time?

[kca]

Re: Yellow discoloration on Panasonic 50" Plasma - VSUS option missing in service m

This set was manufactured in April 2007.

[Andrew F. Ali]

Re: Yellow discoloration on Panasonic 50" Plasma - VSUS option missing in service m

I think you cannot do a V-SUS adjustment via the Service Menu. Then you will have to open her up and look on the PSU adjustment and Test-Point. What is the V-SUS voltage on the label? See if what you measure at the Test-point match what the label says. If not take your time and slowly, carefully adjust the control to bring it to the correct setting. If it is close or the same turn it down a bit and observe the picture for improvement. If none turn the control back up to return the V-SUS voltage to where it was. Observe the picture for any improvement. If none, turn the control to bring the voltage up and observe the picture for improvement. Report your findings.

[Moreno83]

Re: Yellow discoloration on Panasonic 50" Plasma - VSUS option missing in service m

As Andrew says , first measure the voltage to see if it matches the panel sticker. You could also adjust it slightly.

[kca]

Re: Yellow discoloration on Panasonic 50" Plasma - VSUS option missing in service m

Thanks all ~

Took the cover off and measured voltage. It initially read 190.2. The panel sticker read 188. So, very close. However, without making any adjustments, I measured the Vsus again just a minute or so later and it was reading 180.6. Strange. Not sure which was the “true” initial voltage.

Spent the last hour tweaking the Vsus voltage slowly down then up, and here are the results:

At 188 (definitively), the yellow was present. Not much different than what I’ve been seeing for the last couple of days.

At 180 .... much improved. Some very minor patches of yellow popping up from time to time. Almost imperceptible, but still there.

At 195 .... pretty bad. Yellow covering the white (ice of a hockey game live replay from last night) in a very noticeable way. Worse than at 188.

At 198 .... even worse. The yellow now shows up and pretty much blots out the white uniforms of the visiting Washington Capitals. Clearly not the right direction to be turning the Vsus voltage up in this particular tv set and under this circumstance.

So, I took it way back down to 178. Results are quite good. If I look really hard and close, I can see some yellow tinge. This is even true with the menu settings “cranked up” high. Meaning, on Vivid, with Picture on +30 (the highest it will go), Brightness +30, Color +30, Sharpness at 0, and the Color Temperature setting on Cool (vs. Normal or Warm).

Going to leave it on 178 for a while now and observe.

But here are some questions I have as I do:

1) How abnormal is it to have to turn the Vsus down by 10v to get this yellow to fade?
Most of what I read yesterday about Panasonic plasmas and this yellow issue said I’d have to turn the Vsus up.

2) Is it safe to run it 10v lower than the panel sticker recommends for a long duration of time?

3) Can I safely go any lower? I’m thinking 174 or 175 might get rid of this final, very minor yellow that is now rarely appearing.

4) Should I be thinking about any concurrent adjustments while I still have the back panel off today? I read on another forum where a guy moved the Vad down to help compensate for the fact that he had moved his Vsus setting up. My situation would be the opposite. Should I move the Vad up in relation to the fact that I had to move the Vsus down by 10 full volts already? Or, should I just leave these other pots alone and focus ONLY upon the Vsus setting?

Thanks, in advance, for the replies. I find this help invaluable.

~ kca

[Andrew F. Ali]

Re: Yellow discoloration on Panasonic 50" Plasma - VSUS option missing in service m

I think you should leave the other pots and concentrate on the Vsus potonly. Lower voltage is better but not too low. Go to the lowest you can to get acceptable picture and observe it there for a while.

[kca]

Re: Yellow discoloration on Panasonic 50" Plasma - VSUS option missing in service m

Update :

Decided to try 174.5 volts and it was good but suffered more image retention (pink/purple lingerings) during channel changes on white screens than I was comfortable with. Also, a yellow patch appeared during these channel changes on the left side of the screen.

Turned it up to 176.

This seems to be the “sweet spot”. Been running it here for a couple hours now. Looks as free of the yellow as I’ve ever seen it. Gone, for all intents and purposes, even on the hockey ice that I’m now watching.

Very little image retention on those channel changes. And, what is there fades in about 3 seconds. That could probably be improved a bit by turning the Vsus back up closer to 178-180, but then the yellow begins to creep back in.

Going to leave it at 176v for the remainder of tonight and tomorrow. It seeems very stable and therefore safe to do so. I’ve turned it off and back on twice now in the last two hours. Has no problem firing up, catching the DirecTV signal, and staying lit with the same intensity on the screen each time.

I’m content ..... for the moment. Will update again tomorrow.

If anyone thinks 176v (meaning 12 volts lower than the panel sticker’s target of 188) is TOO low, please let me know and please explain why that could be problematic.

p.s. ~ I did not adjust any of the other pots and I don’t foresee the need to do so at this point in time.

[Moreno83]

Re: Yellow discoloration on Panasonic 50" Plasma - VSUS option missing in service m

It would probably be not problematic. Definately dont go to high , it will damage the panel. Same if you play with the other potmeters. (Vc).

Leave it as it is now , this is most likely panel issue or software timing which both you cant change.

[Andrew F. Ali]

Re: Yellow discoloration on Panasonic 50" Plasma - VSUS option missing in service m

It would probably be not problematic. Definately dont go to high , it will damage the panel. Same if you play with the other potmeters. (Vc).

Leave it as it is now , this is most likely panel issue or software timing which both you cant change.

I agree with Moreno83, here.

[kca]

Re: Yellow discoloration on Panasonic 50" Plasma - VSUS option missing in service m

Seems to be working pretty well now, even after a few days of use. Just going to leave it as is and button up the back panel. Thanks to everyone who helped here. Much appreciated.

[tom66]

Re: Yellow discoloration on Panasonic 50" Plasma - VSUS option missing in service m

I've found Ve to have an effect on cyan tinting in white on a Panasonic plasma before - that might be another avenue to explore if this does not permanently resolve the issue.

The only issue with low Vs is that you could get pinking in white, and there's a very very small chance on certain image patterns that the set may shut down with a 6 blink code as the MID voltage drops below a threshold.