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Old 04-29-2012, 01:22 AM   #1
gamergomer
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Default lg 42pc3dv perfect sound, messed up picture

So I see others issues with this tv and no picture, but what about a bad picture?

My picture is dim, fuzzy, has black patchy areas (that change position, not a shattered screen). The sound is perfect. It also flickers bright. When in high power mode, it flickers about once a second. In low power consumption mode, it flickers once every two seconds.

These pictures actually look brighter than real life. The picture's pretty dim in real life:



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Old 04-29-2012, 11:27 PM   #2
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Default Re: lg 42pc3dv perfect sound, messed up picture

Ok, so I took the back off today. Not a single bad cap from what I see.

But I played around with seeing what unplugging different boards and then powering it on did. I notice that there is a snapping comming from the right-most (from back) board (closeup included). The popping or snapping goes away when the board is off. It seems to be coming from the top half of the board and I thought from the left side (bad solid cap?).

I unplugged this board while running and the left picture (from front)dissapeared. The right picture looked pretty good except it pulsed. If I unplugged what I think is the problem board before turning the tv on, I just didn't get any picture at all.

Any suggestions for what's next if I want to try pinpointing the component rather than just trying to replace the whole board?



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Old 04-30-2012, 12:57 AM   #3
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Default Re: lg 42pc3dv perfect sound, messed up picture

This is a bad Z-sustain - the board on the right, as you have diagnosed.

The problem is with the hybrid module, which is under that large heatsink. Replacing the hybrid module is difficult, but not impossible. It requires good soldering skills because of the awful design LG used with these plasma TVs.
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Old 04-30-2012, 02:08 AM   #4
gamergomer
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Default Re: lg 42pc3dv perfect sound, messed up picture

Any ideas how to figure out what hybid module I need and are there pictures for what the job will look like anywhere?

I'm a computer tech and I've soldered and unsoldered lots of old school eproms, but I always hated things like soic. This looks like it's full size but that it's a pain because of the fact that you can't remove the heatsink beforehand.

Ok so I see these:
http://vacation-tripadvisor.com/ebay...9&site=EBAY-US

http://www.ebay.com/itm/4921QP1027P-...item19d00e5d59

Is this what I want? It looks like the same part for either side hybrid?

Is there any way to improve the design when I'm done to keep this from happening again?
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Old 04-30-2012, 10:52 AM   #5
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Default Re: lg 42pc3dv perfect sound, messed up picture

The second eBay link is what you need. (If the pin out and old device are the same - check before buying!) You'll probably also need to replace the fuse for Vs on the board.

Hybrid failure is common on these LG plasmas. I have no idea if LG fixed it with later hybrids.

Last edited by tom66; 04-30-2012 at 10:58 AM..
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Old 06-11-2013, 10:28 PM   #6
gamergomer
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Default Re: lg 42pc3dv perfect sound, messed up picture

Excuse me for reviving a long dead thread, but I have another question about the same TV.

I ended up buying another zsus board. The same exact zsus board was expensive, but there are a lot of very similar boards (search ebay for "lg zsus"). The one I ended up getting had the ebay title "LG 6871QZH056B 6870QZH004B 6871QZH956A". I don't have comparison pictures and have long since thrown out the old board, but the replacement board was the same circuit board with more stuff populated.

So after replacing it, it's worked great. The only small issue is that there are about 20 red snow dots mainly on the left half of the screen that constantly flicker. You can't even see it except in dark scenes and it's fine for the bedroom tv this became.

I remember reading something saying that I should make sure that some voltage setting was the same on the left and right sustain boards. Is that something I should check and do you think that a slightly different voltage would cause the issue? Or do you think that it's just the fact that I didn't get the same exact board?
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Old 06-12-2013, 12:38 AM   #7
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Default Re: lg 42pc3dv perfect sound, messed up picture

Yes. You may also need to update the firmware. One user here offers a service for around $25 to repair this issue.

http://www.badcaps.net/forum/showthread.php?t=29263
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