LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

[sandtang]

Hello,

This is a plasma TV.

Problem:
Couple of months ago, image suddenly started juddering and flipping (left-right mirror), with horizontal streaks. Video of someone else's TV with similar problem: https://www.youtube.com/watch?v=g7-YrQVXAUM
There will also be small clusters of black pixels around. Problems show even in system menu, so not input/source/cable issue. Audio is perfect.

Hardware fix attempts:
I checked the web for ideas but still uncertain so I ordered 5 parts at one go (cost ~US$210 shipped). Replaced each piece in turn and problem remained. I've attached photo showing parts replaced. This means all 5 new and old parts are all working, problem lies elsewhere unfortunately.

Software fix attempts:
Then, friend with similar problem recommended changing contrast and colour settings. Surprised that it fixed the problem! BUT once TV restarted, problem returned.
- reducing Contrast seemed to reduce shaking/flipping
- reducing Blue colour seemed to reduce black pixels
But does not work every time, so overall inconsistent. No fix.

I'm at a loss and really disappointed, especially since this TV is gorgeous and only 3.5 yrs old. I'm not skilled at the component level, so don't know how to solder or check current, etc. I'm hoping for some simple fix ideas before giving up and dumping my precious.

Thank for reading!

[ljintexas]

Re: LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

I always start with the power supply board. Looks like that is one of the only boards you have not replaced. In the center. Look for signs of heat.

[tom66]

Re: LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

Power supply almost certainly NOT the cause of this fault.

Is probably main board fault, the board with HDMI etc. To determine the exact cause, it is best to run test patterns on control board.

Can you get a close up picture of the lower center board in the set (it's green; this is the control board.)

[ljintexas]

Re: LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

I concur Tom, but many times issues such as this have been resolved simply by removing, inspecting, and reinstalling boards...poor connections on harnesses.

[sandtang]

Re: LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

Thanks for the super quick responses guys. Really appreciated.

Okay I attached close up photos of control board (and main board too just in case).

When I ordered the parts from Shopjimmy.com, they didn't have the main board in stock and it alone costs over US$100, plus inputs were working so my lay self didn't suspect it...

[tom66]

Re: LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

Ok, I've highlighted a few things.

- Unplug the TV.
- Place a jumper across holes marked R51/R52 in red ring, use a small piece of wire to connect both holes
- Disconnect cable in red ring (press each side and pull gently)
- Plug TV into mains power and take it out of standby.
- You should get test patterns cycling on the screen like THIS: https://www.youtube.com/watch?v=9LcqLM5TRHk although the exact pattern may vary

Note in this mode the user menu, etc. will be unavailable and you will have to turn off the TV by using the remote control.

See if the patterns show any sign of glitches: if not, the fault is almost certainly the main A/V board. As this test removes the main board from the equation completely.

[sandtang]

Re: LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

that I can do....
and I let it cycle 4 times for good measure... the tests were flawless!


[words cannot describe how much I wished I'd found this site (and tom66) _before_ I ordered all those parts... and I'd researched for days... damn you google!]

[tom66]

Re: LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

Great. SJ has a return policy (with restock fee), so maybe consider sending boards back, and getting a main board?

[sandtang]

Re: LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

Yes, will do that.
Unfortunately no one seems to have my main board variation EAX61744403... should be region specific... will keep searching.

Thanks very much again Tom!

[sandtang]

Re: LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

just a mini update...
bad news.. shopjimmy can't accept returns after 30 days (my fault for procrastinating so long)... and my main board (EAX61744403/EBU60742922/EBT61115501) still can't be found anywhere... *sigh*

[tom66]

Re: LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

You might have to sell the boards yourself online. As for the main board, LG will usually sell them, even to private customers... check out EncompassParts or SearsParts, I hope they ship to Singapore.

Region specific setting only affects TV tuner, so if you can only find US version you could buy a terrestrial/cable receiver box to tune into Singaporean TV...

[sandtang]

Re: LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

That's wonderful info cos I don't use tuner since I have cable. I might have to use a forwarder to ship.

Thanks for the advice Tom!

[tom66]

Re: LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

Oh, and it also affects what languages are available but I assume your TV will be set to English (US TVs usually only have English/French/Spanish)

[mmartell]

Re: LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

Have you tried to heat/cool the main board when these symptoms occur ? Wonder if it's a bad ram chip or eeprom ic, or perhaps a regulator feeding one of them.

[sandtang]

Re: LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

Oh, and it also affects what languages are available but I assume your TV will be set to English (US TVs usually only have English/French/Spanish)

Yup English will do.

[sandtang]

Re: LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

Have you tried to heat/cool the main board when these symptoms occur ? Wonder if it's a bad ram chip or eeprom ic, or perhaps a regulator feeding one of them.

As I recall, in both cases they didn't make any difference unfortunately. Problems will be there every time I switch it on, whether cold start, or after an hour or two of troubleshooting.

[sandtang]

Re: LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

Another update that my TV's fixed after replacing the main board!

Long version:
So unfortunately (actually, fortunately) EncompassParts and SearsParts only sell main boards to authorised service agents, while shopjimmy had no stock. I read somewhere that LG will not sell boards to customers since they are not customer serviceable parts. But in desperation, I emailed LG Singapore anyway and they replied that they have the main board at US$87, no warranty though. I picked it up right away, installed and tested it for couple hours since yesterday. All good now! My beautiful TV is back on its throne.

Strangely it's an Australian/NZ board but didn't matter at all. At default Antenna input, it had small green specks all over the screen! LG screwed me again.... I almost gave up and admit defeat, but then decided to try other inputs just in case. And success! Everything else works perfectly.

I forgot to copy all my previous (perfect) settings on the original main board and was too tired to put it back, so spent another hour configuring the new board. Happy now and hope it lasts. Once again, thanks to Tom for confirming source of problem and sharing his advice.

Personal note: I will not likely buy LG again. We have 3 other low-mid range Panasonics in the family and they all still work fine after 8 years of heavy use.

[tom66]

Re: LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

I am quite surprised the board was that cheap from LG. Not too bad, I suppose.

LG are better than Samsung but not as good as Panasonic.

If I were to buy a new TV it would be Panasonic or >42" LG or >60" Sharp, a lot of products are rebadged these days, so you should avoid buying any smaller sets not from Panasonic, who I believe are the only company not to re-badge crap as their own.

[sandtang]

Re: LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

Yup was cheaper than I expected. All in, I spent only tens of dollars more than if I requested for LG's service, and certainly a lot less than a new TV. Plus I have a whole set of spare boards for future use (if no one buys them).

Now I'm extra gentle plugging in cables to the main board. In fact I leave a USB extension cable attached to avoid unnecessary physical contact with the board over USB devices.

Your support for Panasonic makes me even more certain now. Nice

[sandtang]

Re: LG 50PK950-TA shaking/flipping image (replaced 5 boards still the same)

Report back that not only is my TV still working fine, a second TV was also fixed as a result of Tom's excellent advice!

That 2nd TV belongs to the friend I mentioned in first post. We didn't realise at that time that his TV is the same as mine! Freaky coincidence. So we used the same technique to isolate main board, test and replaced it. His family is so happy now.

So thank you once again Tom!