Faulty 42" plasma tv LG Rz-42px11

[Mikeyboy2007]

ok guys new tv new problem. tv when switched on was scrolling 3 bars of white across the screen slowly, when switched to AV it would glow up white with coloured pixalisation. then when switched back to channel 1 or whatever scrolling lines again.. any ideas ?

similar to this https://www.youtube.com/watch?v=UqutIxlStk8

[tw2005]

Re: Faulty 42" plasma tv LG Rz-42px11

ok guys new tv new problem. tv when switched on was scrolling 3 bars of white across the screen slowly, when switched to AV it would glow up white with coloured pixalisation. then when switched back to channel 1 or whatever scrolling lines again.. any ideas ?

similar to this https://www.youtube.com/watch?v=UqutIxlStk8

If it's like the youtube, he gives a solution a bad buffers. The scrolling bar is actually the small "No signal" image as it skips around the screen. most likely only one buffer board is bad. I have worked on an old LG 42PX10/11 which displayed large bands of coloured snow moving around and that one was a bad bottom buffer board. I completely isolated it from the ysus and the small interconnecting cable from th top buffer and it produced a perfect top half.

maybe you can work out which is bad having a closer look at the buffer boards.

[Mikeyboy2007]

Re: Faulty 42" plasma tv LG Rz-42px11

will give that a try tomorrow mate and will try upload a video of the tv i have. thanks

[Mikeyboy2007]

Re: Faulty 42" plasma tv LG Rz-42px11

If it's like the youtube, he gives a solution a bad buffers. The scrolling bar is actually the small "No signal" image as it skips around the screen. most likely only one buffer board is bad. I have worked on an old LG 42PX10/11 which displayed large bands of coloured snow moving around and that one was a bad bottom buffer board. I completely isolated it from the ysus and the small interconnecting cable from th top buffer and it produced a perfect top half.

maybe you can work out which is bad having a closer look at the buffer boards.

so if that is what the problem is you think i oculd just replace the mosfits on the board or would it have to be the full board ?

[tw2005]

Re: Faulty 42" plasma tv LG Rz-42px11

so if that is what the problem is you think i oculd just replace the mosfits on the board or would it have to be the full board ?

I think the 50PC1 buffers have SMD fets on the buffer boards. I think that's what he's referring to. I don't yours does but i can't remember now. I replaced the bad buffer as the buffer IC was smoked.

I think those buffer boards are both hard to find and very expensive now??

[tw2005]

Re: Faulty 42" plasma tv LG Rz-42px11

Actually maybe not so hard and expensive. Just had a look it was the Px10 i did but I suspect it was the same buffers as the PX11.

did a search on 6871QDH066,6871QDH067 got plenty of hits with PX11 models showing as well. Don't see any SMD FETS on the buffers.

There's A & B revisions could be interchangeable.

compare left yours, right 50Pc1, you can see the FETs that guy was talking about. Pinced the photos off ebay so they won't blow up in size.

[Mikeyboy2007]

Re: Faulty 42" plasma tv LG Rz-42px11

took out the bottom buffer board and top half of the screen displayed as normal so is there a way to repair the buffer rather than replace ?

[tw2005]

Re: Faulty 42" plasma tv LG Rz-42px11

You must be either bored or looking for a serious challenge

SMD Hot Air rework replacing those buffer ICs. Can't advise, never done it, If you have the skills and equipment go for it.

[Mikeyboy2007]

Re: Faulty 42" plasma tv LG Rz-42px11

my mate has a rework station but you think im better just going for a new bored ? seems like a bit of a pain n to be honest a dont think a would have the patience for it, the buffer ICs are all covered in appoxy

[tom66]

Re: Faulty 42" plasma tv LG Rz-42px11

It's "epoxy", and you can peel it off, but you will likely have to replace all of the ICs on there.

[tw2005]

Re: Faulty 42" plasma tv LG Rz-42px11

I think the chip is SN755866. 100pin and the centre section soldered as well, prices ranging 5-10USD per chip. I don't think I'd bother but ask your mate.

For the challenge and experieince maybe, but getting a working board is probably more economical. I have read best practice to replace both buffer boards but I'll stop here, everyone has there own ideas, you found the problem quick smart so the rest is up to you.

[Mikeyboy2007]

Re: Faulty 42" plasma tv LG Rz-42px11

I think the chip is SN755866. 100pin and the centre section soldered as well, prices ranging 5-10USD per chip. I don't think I'd bother but ask your mate.

For the challenge and experieince maybe, but getting a working board is probably more economical. I have read best practice to replace both buffer boards but I'll stop here, everyone has there own ideas, you found the problem quick smart so the rest is up to you.

thanks for help mate

[Mikeyboy2007]

Re: Faulty 42" plasma tv LG Rz-42px11

got a not bad deal on these tw2005. both buffer boards for under £50 seller refurbished http://www.ebay.co.uk/itm/1710001702...84.m1423.l2649

[tw2005]

Re: Faulty 42" plasma tv LG Rz-42px11

I think the term refurbished is a little misleading. Says used further down, hope it works out for you.

[Mikeyboy2007]

Re: Faulty 42" plasma tv LG Rz-42px11

cheers buddy, will update you once they have arrived