Samsung HP-S4253/X/XAA center screen discoloration

[TomMcc]

I have had this set since new and never had any problems. Recently I started noticing a blotch of red and green engulfing the center of the screen. It's especially noticeable on light/white backgrounds, and expands and contracts with picture movement. I have investigated as best I can and am leaning towards it being the Y sus and or main. If it is I think it's best to replace both while I'm in there.

I was hoping someone may have seen this issue before and can confirm. I am really just interested in replacing the boards, since the tv is relatively old and will probably start nickel and diming me with on-board fixes. By the same token, I don't want to play hit and miss, replacing good boards.

I have attached several images to show the condition. I have also shared a folder that has the images and several videos so you can see how the discoloration reacts to screen movement.

Thanks in advance for any insight or assistance. Really appreciate it.

tom

Link to shared image and video folder: http://1drv.ms/1gJTzY4

[TomMcc]

Re: Samsung HP-S4253/X/XAA center screen discoloration

Nobody has seen, or experienced this issue before, or can offer any advice. Sure would appreciate it.

[tom66]

Re: Samsung HP-S4253/X/XAA center screen discoloration

Looks like a power supply voltage may be low or needs adjusting to compensate for aged plasma panel.
Do you have a digital multimeter available?

[TomMcc]

Re: Samsung HP-S4253/X/XAA center screen discoloration

no Tom, unfortunately my tools are somewhat limited. I can probably get hold of one from a buddy. If you tell me what to check for I'll have a go at it. I do also have the service manual for reference, so I can follow any suggestions you have.

[tom66]

Re: Samsung HP-S4253/X/XAA center screen discoloration

OK, do you have the TV open? Inside the TV there is a reference sticker with the voltages for each part of the panel labelled. You will need to borrow a meter and verify each major voltage is present and stable.

[TomMcc]

Re: Samsung HP-S4253/X/XAA center screen discoloration

ok Tom, will do, thank you. I'll report back what I find in a couple days. Thanks again.

[TomMcc]

Re: Samsung HP-S4253/X/XAA center screen discoloration

Hi Tom, sorry for the delay but borrowing a meter proved harder than I thought, so I just bought one and did the test. The results are as follows with label/my reading:

VA 65 / 65
VS 198 / 171.3
Ve 105 / 107.5
Vset 195 / 199

[tom66]

Re: Samsung HP-S4253/X/XAA center screen discoloration

Your Vs voltage is way too low. Can you see the adjustment point? Small little screw pot. Try increasing it to match the 198V rated voltage.

[TomMcc]

Re: Samsung HP-S4253/X/XAA center screen discoloration

yes, the adjustment screw is very easy to get to. I'll raise it and let you know what happens.

[tom66]

Re: Samsung HP-S4253/X/XAA center screen discoloration

If it won't increase then you will have a power board issue, I wonder if when there is less white on the screen it returns to normal.

[TomMcc]

Re: Samsung HP-S4253/X/XAA center screen discoloration

wow, amazing, got it to a steady 197.7+- and what a difference. I think it actually solved the whole discoloration issue. Thanks so much Tom...

To answer your question, yes, on dark backgrounds it was much less noticeable, the opposite of what most experience from what I've read. It was blurred and grainy/noisy on dark images, but the discoloration was far worse on light backgrounds.

[tom66]

Re: Samsung HP-S4253/X/XAA center screen discoloration

Nice to hear, enjoy the TV!
While you're there, you might want to adjust the other voltages to match the sticker and clean out any dust build up.

[TomMcc]

Re: Samsung HP-S4253/X/XAA center screen discoloration

Absolutely Tom, tweaked, tightened up and clean as a whistle.
You're awesome my friend, thank you....