LG Plasma - Thin horizontal line flicker and mirror image

[JediL1C1OUS]

hi All,

This problem has been bothering me for awhile now. It's intermittent but dependent on what is on the screen I believe, because it can be repeated if you rewind over the same scene again or pause it when the issue happens. It also effects the on screen menus when it happens. I've uploaded a YouTube video of the issue.

Yesterday I noticed it also mirrors the image during the flickering. I paused it on a scene that was causing this. Any ideas?

Thanks!

[tom66]

Re: LG Plasma - Thin horizontal line flicker and mirror image

Well, that's an odd fault.
Care to share the model number of your TV?
If it's a newer generation LG plasma (2008 onwards) a simple test should be able to determine the cause of the fault.

[JediL1C1OUS]

Re: LG Plasma - Thin horizontal line flicker and mirror image

Thank you for the quick response. It's an LG 60PK540 that I bought in 2011.

[JediL1C1OUS]

Re: LG Plasma - Thin horizontal line flicker and mirror image

Well, that's an odd fault.
Care to share the model number of your TV?
If it's a newer generation LG plasma (2008 onwards) a simple test should be able to determine the cause of the fault.

So what is the simple test I can do?

[tom66]

Re: LG Plasma - Thin horizontal line flicker and mirror image

Can you supply a picture of the TV with the back cover off, and pictures of all visible/easily accessible circuit boards.

[JediL1C1OUS]

Re: LG Plasma - Thin horizontal line flicker and mirror image

Can you supply a picture of the TV with the back cover off, and pictures of all visible/easily accessible circuit boards.

I'll work on this... Need someone to help me get it down. What are we going to be looking for?

[tom66]

Re: LG Plasma - Thin horizontal line flicker and mirror image

A small connection point where you can jumper two holes on an internal circuit board, this will engage an automatic test pattern mode. If the mode flickers after some time, it indicates a fault with the Control/Logic PCB. Otherwise, the fault likely lies with the Main AV PCB.

[JediL1C1OUS]

Re: LG Plasma - Thin horizontal line flicker and mirror image

A small connection point where you can jumper two holes on an internal circuit board, this will engage an automatic test pattern mode. If the mode flickers after some time, it indicates a fault with the Control/Logic PCB. Otherwise, the fault likely lies with the Main AV PCB.

Ah, that makes sense. Easy way to determine if it's the main board since it wouldn't use an external source. I guess using the OSD would also help determine this, correct? If I disconnect all inputs and am able to reproduce it with the OSD then it's not the main board. I'll try both, starting with the latter, and report back. Thank you.

[tom66]

Re: LG Plasma - Thin horizontal line flicker and mirror image

Well, if the OSD does not flicker, it would indicate more than likely it is the main board.
But sometimes the OSD can flicker even if the main board is bad, so it's not 100%.

[JediL1C1OUS]

Re: LG Plasma - Thin horizontal line flicker and mirror image

Well the OSD was just doing the exact same thing as in my previous video with no inputs connected and just the menus on over a black screen

I'll still take it apart to start the internal test sequence and see if it's repeatable.

[JediL1C1OUS]

Re: LG Plasma - Thin horizontal line flicker and mirror image

Would using the color wash ISM also be a good test or just stick with the jumper initiating the test pattern?

[tom66]

Re: LG Plasma - Thin horizontal line flicker and mirror image

Just post the pictures of the boards when you take them, and I will highlight the test point.

[JediL1C1OUS]

Re: LG Plasma - Thin horizontal line flicker and mirror image

Just post the pictures of the boards when you take them, and I will highlight the test point.

Here's another oddity, if it means anything. With the issue happening while the OSD is up, if I place my hand over all the inputs (touching the connectors on the main board), it stops the flickering. I tested this multiple times and somehow it stops the flickering.

[JediL1C1OUS]

Re: LG Plasma - Thin horizontal line flicker and mirror image

Just post the pictures of the boards when you take them, and I will highlight the test point.

So I have the back panel pulled off. There's only 2 boards that appear to have jumpers, which seem to be enabled/disabled by turning them like a screw.

Can you tell which jumper it is from these or do I need to take a better picture of one of these boards?

[JediL1C1OUS]

Re: LG Plasma - Thin horizontal line flicker and mirror image

Well I just looked at your thread about running the self test and so apparently I'm looking for a jumper like on a pc motherboard. I'll need help figuring out which one.

[JediL1C1OUS]

Re: LG Plasma - Thin horizontal line flicker and mirror image

Sorry, here is the control board. I'm assuming I need to jump R51/R52 with a wire? Do I need to do anything else like unplug something?

[JediL1C1OUS]

Re: LG Plasma - Thin horizontal line flicker and mirror image

I figured it out and have had the test pattern running for awhile now but did not see the flicker or line. The flashing light on the control board has been green for everything.

I ordered a replacement main board from eBay which arrived today and that didn't fix the problem either, as it was showing the fault again after being on for maybe 10 minutes and messing with the OSD. I seem to be able to get it to fault when using the OSD... can that be the problem? This issue is driving me mad. Ugh.

[Alastair E]

Re: LG Plasma - Thin horizontal line flicker and mirror image

It may be worth checking all the ribbon-connections to the Control-Board....

I had a very odd fault where approx 2" of picture near the middle of screen from top to bottom were absolutely perfect--But completely reversed left to right.....
--There was no other effect on the screen at all and the picture otherwise was faultless.
--This was on a Philips Plasma with as I recall, Hitachi/Fujitsu Chassis.

Turned out that one of the tab connections to bottom buffer board was not seated correctly, and removing and refitting cured the issue.....

You never know--might be something similar....

[JediL1C1OUS]

Re: LG Plasma - Thin horizontal line flicker and mirror image

Is the OSD controlled/run by a certain board?

[tom66]

Re: LG Plasma - Thin horizontal line flicker and mirror image

OSD is all on the main board.
There is a small but non zero chance that the control board is causing this issue.