LG42pj350 plasma tv - troubleshooting

[ziegler]

So I got this LG tv, where there are about 4 stripe groups, they are kind of close to the middle and they fill about 1/4 of the Whole screen.
When the picture is over the stripes, it changes it's color and there is some weird noise over the groups.
The stripes are vertical, from the bottom, to the top (they are way bigger than 1 px, maybe between 150px - 300px).

(Photos will be uploaded later today)

The rest of the screen works fine and give a normal color.

I don't think that I will be able to repair it, so I want to just switch the broken board out.

The one question I have is, what board should I replace, the buffer board ? or the main board ?

[tec5c]

The odds of this fault being a related to any of the boards is quite slim. More than likely the panel is the culprit here, though pictures will help to clarify this.

Oh and also, this era of plasma's from LG was a notoriously bad time for panel faults.

[ziegler]

Here are some photos of the problem

[ziegler]

Here are some photos of the boards.

[ziegler]

There is coming a big power noise from the right powerboard.

it's the board that can be seen at the first and last photo, from my last post.
( IMG_20151016_154021.png , IMG_20151016_153816.jpg )

The last photo is around the source of the sound, but I couldn't find the part that is making the sound, from my ear along.

Not sure if this is connected to the screen problem.

[tec5c]

The only board I would even think about replacing is the logic control PCB (visible in the 4th and 5th photos from your previous post... It's the small green rectangular shaped PCB)

It's a bit of a gamble to buy a replacement board as there's quite a high probability of the fault being in the panel itself, so perhaps you want to think about it or even try to source other alternatives for boards (i.e., does a friend have the same model TV that you could quickly swap boards in order to see if it effects the fault...)

[ziegler]

The only board I would even think about replacing is the logic control PCB (visible in the 4th and 5th photos from your previous post... It's the small green rectangular shaped PCB)

It's a bit of a gamble to buy a replacement board as there's quite a high probability of the fault being in the panel itself, so perhaps you want to think about it or even try to source other alternatives for boards (i.e., does a friend have the same model TV that you could quickly swap boards in order to see if it effects the fault...)

I feel the same way.

I don't know anyone with the model, but my sister used to have a model that look alot like this.
I say this because, that model didn't make any sound (that could be heard by the human ear), but this one does.

So lets say that I buy a new buffer board, and the problem goes away, but the sound will still be there. (That power-board probably don't got long time left to live)

I'm not buying 2 boards for this TV, it will cost more than I want to use.
(the power board could be fixed easy (maybe), but I'm not sure what to look for)

[tec5c]

If you're working on a budget to repair this TV I wouldn't be buying any boards in an attempt to repair it.

[ziegler]

I found this post on the net, which could be just the fix for my buzzing problem.

------------
http://www.gamespot.com/forums/pc-mac-linux-society-1000004/my-plasma-tv-started-buzzing-loudly-solution-29342652/

#8 Posted by wurydaz (311 posts) - 2 years, 8 months ago

Maybe this will help you out maybe not - I recently bought a new 60'' panasonic plasma , after about 2 months of ownership i got the dredded buzzing , tv is on warranty , caled panasonic , they sent a repair man out to me and it turns out that the problem was the original screws that were instaled with the tv did not have washers to dampen the vibration at the end of them , he quickly took about 40-75 screws out of the tv and replaced them and so far not a vibration or buzz is to be heard. Hope it helps as this is not always the issue.
------------
does this sound believable ?

If this work, then I'm back on the plan, to buy a new buffer board (that board is way cheaper than all the other boards)
The good thing about all this is, if this works, then I got a 42 inch TV that I got for free (minus the price on that buffer board).

[Shock]

Possible but extremely unlikely, I count about 5 possible major parts likely to contain the fault, it could even be a cable.

I think you should make a decision if you are going to put serious time into learning electronics troubleshooting or not and let that decide your next move. It's better if you have a specific electronics related question, because these kind of questions without you doing a lot more isolating or ruling out possible causes your end will fall into the realm of guesswork for others.