LG 50PM1m Plasma - only top of screen working

[karidan]

Hello all,

I have a 50 inch LG Plasma that only displays video on the top 1/6 of the TV. The working part looks 100% normal. It doesn't matter which input is used. The bottom 5/6 is just black but it has backlight. I've looked around on various forms but haven't found anything about this specific problem. Most similar posts involve either the entire top half or the entire bottom half (or both) displaying nothing.

It looks like some of the caps on the power supply are swollen and leaking so I'm sure this has to be addressed but what (if any) parts should be checked out or replaced at the same time?

Thanks

[chrismurphy]

Re: LG 50PM1m Plasma - only top of screen working

faulty buffer boards

[karidan]

Re: LG 50PM1m Plasma - only top of screen working

Hello all,

I've been busy and just now got the time to start working with this again. I replaced the power supply and also the buffer boards as suggested. I used a multimeter to adjust the VA and VS to match the values inside the rear cover (192v and 68v). The TV powers up now and works fine- mostly. When I first turn it on I get a perfect picture on all inputs but within 10-15 minutes the picture starts to shift to pink/red especially on the edges along with some flickering. I can also see some burn in in light areas of the screen of images recently on the screen. This is especially apparent when selecting "white wash" from the menu.

Once the TV starts doing this I can connect a computer with the same result but what's interesting is if I open a mostly white window full screen (Google search page for example) it will look pink and distorted until I reduce the browser window down to less than 1/4 of the screen. When I do this the white looks perfect and there's no flickering or discoloration when the rest of the screen is on a black background. Also, if I turn the power off and back on the TV has the same problem. If I leave it off for awhile- maybe a couple of hours it works fine again for 10-15 minutes. If the contrast is reduced down to 15, brightness reduced to about 30, the problem is reduced but not at all eliminated.

I'm hoping this is a cold solder connection problem or connection problem somewhere that I've been unable to find. I've removed and reseated every wire and ribbon I can find except the ones on the right (x driver board?)

Any input greatly appreciated

[mmartell]

Re: LG 50PM1m Plasma - only top of screen working

Don't know about this model in particular but check the solder on back side of the z sustain where the large coils are for cracked joints. Also make sure all screws are fastened tightly. Z sus is on far right.