LG 50PK950 - No image shown

[Warner]

Hi,

My Plasma TV broke down today. When turning it on (with either with the remote or the touch-screen buttons), the screen lights up as normal (meaning it's lights up first and then becomes almost black but visibly light in a dark room), but no image is shown.

I've tried removing all the inputs, removing the power for a while, and now I'm looking inside.
- The controller board led is flashing 'long-short-long-short'
- With the main board disconnected there is no difference in the behavior (no test patterns or anything)
- With the main board disconnected, the controller board is still flashing 'long-short-long-short'

My thought is it must be the main board.. (I read several threads with similar issues).

What I can see is the attached picture, which looks to me like a broken capacitor, but I don't have so much experience. Can anyone have a look and give me their opinion? What could I measure to verify this is the cause?

[Warner]

Re: LG 50PK950 - No image shown

Here's a picture of the full backside for reference

[R_J]

Re: LG 50PK950 - No image shown

With the tv unplugged, locate the control board, (just below the power supply) and unplug the cable (P31) that goes to the main board. On the control board there are two points (lower right corner) connected to R51 & R52. you need to place a short across those two silver points and plug the tv in. This should generate test patterns on the screen. If they are ok, the fault ison the main board
That cap does not look bad, was something spilled on the tv, it looks more like water damage.

[Warner]

Re: LG 50PK950 - No image shown

With the tv unplugged, locate the control board, (just below the power supply) and unplug the cable (P31) that goes to the main board. On the control board there are two points (lower right corner) connected to R51 & R52. you need to place a short across those two silver points and plug the tv in. This should generate test patterns on the screen. If they are ok, the fault ison the main board
That cap does not look bad, was something spilled on the tv, it looks more like water damage.

Ok, did that. Indeed, when connecting those two points I'm getting test patterns.

So what could I try now? Any tests to do on the main board?

[aaronwt6]

Re: LG 50PK950 - No image shown

Classis symptom of failed solder joints on the processor of this main board (chip under the black heat sink). You'll need to have it serviced or replace the board.

[Warner]

Re: LG 50PK950 - No image shown

Classis symptom of failed solder joints on the processor of this main board (chip under the black heat sink). You'll need to have it serviced or replace the board.

Yeah I was afraid it would be beyond my capacity to repair.. They are really hard to find though in Europe (and I can't find a servicing company on this continent either).

No way to try and fix this myself? Heat up the edges of the chip so the solder melts back?

[R_J]

Re: LG 50PK950 - No image shown

I don't know what to tell you to check, That cap you mentioned in in thge audio section so I doubt it is the problem. It could be a BGA connection problem on the large ic under the heatsink. Try heating the board and large ic with a hairblower/heatgun and see if it makes a difference.

[Warner]

Re: LG 50PK950 - No image shown

I don't know what to tell you to check, That cap you mentioned in in thge audio section so I doubt it is the problem. It could be a BGA connection problem on the large ic under the heatsink. Try heating the board and large ic with a hairblower/heatgun and see if it makes a difference.

Okay, getting ready for some heat

[Warner]

Re: LG 50PK950 - No image shown

Okay, getting ready for some heat

Well.. there was not much hope, but indeed it didn't work.

The only replacement board I can find is of an LG 60PK950 (same model, larger version). Do you think that could work or will I get problems with the wrong firmware and so on?

[Warner]

Re: LG 50PK950 - No image shown

Well.. there was not much hope, but indeed it didn't work.

The only replacement board I can find is of an LG 60PK950 (same model, larger version). Do you think that could work or will I get problems with the wrong firmware and so on?

Update!

So I tried once again and the the screen came back... but not exactly as we were hoping. Screen is all red and dancing around.

I guess now we can really throw the main board.. Unless anyone has great ideas

[Warner]

Re: LG 50PK950 - No image shown

Update!

So I tried once again and the the screen came back... but not exactly as we were hoping. Screen is all red and dancing around.

I guess now we can really throw the main board.. Unless anyone has great ideas

Okay.. wait a minute.. Is it possible that I accidentally repaired the board but broke the cable?

Now I need your help again... . Does anyone know any tricks to repair a cable like this?

[aaronwt6]

Re: LG 50PK950 - No image shown

Yes, that's definitely the problem now. Also, what did you use to heat the board? If it wasn't hot enough, the issue will problem resurface quickly. As far as the cable goes, you'll almost certainly need a replacement.

[budwich]

Re: LG 50PK950 - No image shown

Okay.. wait a minute.. Is it possible that I accidentally repaired the board but broke the cable?

Now I need your help again... . Does anyone know any tricks to repair a cable like this?

what the hell happened to that????? Surely you didn't heat the board with all the "things" attached.... :-(

[Warner]

Re: LG 50PK950 - No image shown

what the hell happened to that????? Surely you didn't heat the board with all the "things" attached.... :-(

Nonono.. of course not.

I just messed up pushing the cable back in without close attention.

Ordered a new cable - should arrive in a few days.

[R_J]

Re: LG 50PK950 - No image shown

You did'nt release the latch on the connector and just tried jamming the cable in. You must release the latch or this will happen with your new cable as well.

[Warner]

Re: LG 50PK950 - No image shown

You did'nt release the latch on the connector and just tried jamming the cable in. You must release the latch or this will happen with your new cable as well.

Okay, an update:
- new cable ordered
- the heating of the main board worked, but only for a little while. The next morning we were back where we started
- found a main board with a different number (EAX61141606(0) instead of EAX61141603(4). It belonged to another 50PK950. There is a slight difference in the layout just by looking at it. Can it be an updated version from later production that works just as well?


So the question is: Will This Work??

[R_J]

Re: LG 50PK950 - No image shown

There is a connector missing on the (606) board, which is used on your's and likely other components not populated

[Warner]

Re: LG 50PK950 - No image shown

There is a connector missing on the (606) board, which is used on your's and likely other components not populated

Oh darn, thanks so much.. I totally missed the connector there. Okay, that's no good then.

[Nick's Tvs]

Re: LG 50PK950 - No image shown

For the American versions of these boards, they are cross compatible between the 60 and 50 inch models. As well even with several connectors missing on one board vs another you will still get the TV to work. A lot of the times those additional connectors are for higher end modules with additional options such as a connector for a wifi module or a Bluetooth module. If you purchase one of these boards without that connector, you may loose the ability to plug in your Wifi module or your Bluetooth module. If you don't use those features anyways then go ahead and get that board as a replacement. If you aren't sure what that connector goes to, then simply follow the cable to which ever board it plugs into and look up that part number to find out if it is your bluetooth, wifi or other.