Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

[Michale32086]

Referring to this post:

https://www.badcaps.net/forum/showpo...38&postcount=1

In that Tom66 indicates that a "solarize" display is likely the Z-Sustain/X-Main board...

I have an LG that has that problem. Nearly identical to the one picture in that post. The biggest noticable problem is at power on, the INPUT indicator is wanky, as pictured..

I also noticed that, with the exception of the INPUT indicator, the problem only appears to be on the lower third or half of the screen.. That indicates possibly the Y-Buffer board(s)??

I tried 3 different boards I had on hand of unknown workability. Still gave me the same problem..

I ordered a replacement board. It works a LOT better, but still is noticably solarized AKA sparkles...

I was wondering what other board might be contributory to the solarized/sparkle problem..

[Alastair E]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Sounds like the usual Mal-Discharge issue LG are famous for.

Slight adjustment of the SET_Up and SET_Dn can sometimes help as well as lowering the Vs by 5v.

Only Proper cure is--The Control-Board Firmware needs updating. Contact 'Capkid' in the US who has the appropriate F/W and the proper download jig to update it.

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Thanx, Alastair.. Dropped CK a msg...

[tom66]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Doesn't look like normal maldischarge, not sure what this is - does the shadowing appear on everything? Are all voltages, in particular Vsc/-Vy/Vzbias OK?

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Here are a couple better shots of the issues..

Lemme throw it on the bench and pull those voltages..

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

All the voltages look good..

VS Y and X 194v

VA 58v

[Shinju]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

There should be test points on those boards, all you are seeing is voltage from the SMPS at the wireharness.

The TP's on the boards can tell you better what your X and Y are doing.

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

All righty... Let's go there.. Thanx

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Perusing Tom's manuals now...
http://www.toms-service-manuals.com/...&Search=Submit

[Shinju]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

this will help you determain what the other voltages are tied too.

This is for a different LG PDP so make sure to adjust them to your sticker and not this

VSC and VE are on your Ysus (Should be) and Zbias (VZB) is on your Xmain.

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Awesome! Thanx

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

All right, I just had something REALLY wierd happen..

I am still searching for the Testing Points, but I found another Y-MAIN board with buffers identical to the set in the LG...

Just for sheets and greens, I swapped out the lower buffer board.. No change. Still got the analog snow but discolored red/pink on the lower part of the screen..

So I swapped out the upper buffer board and powered the unit up. The screen that came up was a solarized screen of the picture in post #5.. The Title Screen from the BRUCE ALMIGHTY DVD..

I should point out that the LG is not hooked up to anything except power..

How the hell could the title screen from the previous DVD be on there???

[tom66]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Hah... You have discovered that a plasma panel remembers whatever is displayed on it. It is a memory device, that is fundamental to its operation. This is why the US Military crushed every plasma TV used for secret info.

Basically, the cell pixels are initialised by a reset pulse which erases the wall charge to a low, near zero state. In this case, they will not show what image has been displayed previously. If the reset pulse or part of the initialisation goes astray, you'll see some previous images. They are very difficult to erase, but do not show up in normal usage. Sometimes you'll see them flash up when you power up the TV.

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Kinda like The Ghost In The Machine, eh??

It freaked me out..

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

There should be test points on those boards, all you are seeing is voltage from the SMPS at the wireharness.

The TP's on the boards can tell you better what your X and Y are doing.

If I am reading the training manual (thanks Tom66) correctly, VS and VA have no test points. It says to just use the P805 connector pins for test points..

I am at home now and don't have the unit in front of me. I'll follow up when I get to the shop

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Seems there is a discrepancy on the model number..

I didn't have the back of the TV when I started working on it as it was an old project that I came across in one of my storage sheds..

I just found the back and, according to that, this is a 50PCD5..

This opens up a lot of documentation from Tom's Manual site..

[tom66]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

The display panel is most important, and it's a PDP50X4... that's where you'd find Vs/Va/etc.

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Ahhh Got it...

You don't happen to have a 2007 Training Manual floating around?

[tom66]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Try this:

[Michale32086]

Re: Tom66's Plasma Guide "Solarizing" RE: LG PDP50X4

Try this:

Awesome!!

That looks like what I need...

Some of those TPs look like a place to hook up my RIGOL, eh??

Thanx again...