LG 60PG60 - Screen glows, but no top screen picture

[jtieman]

Hello all,
I have inherited an LG 60PG60 plasma TV that has the following problem.

The complete top 50% of the screen is dark, while the lower half works perfectly, shows picture on all inputs and internal menus, etc. If I turn out the lights in the room and turn the set on, both top and bottom halves of the screen are glowing, but the bottom half is slightly brighter, and shows a picture.

I have repaired 2 other plasma sets (a Fujitsu & an older LG), and would assume that this is an upper buffer board failure, but the upper half of the screen is glowing. Not sure if that could still mean the buffer is the culprit? I am still learning as far as Plasma repairs go...

I checked all rails of the power supply on the main large connector on it, while the set was on and noticed all connections had power (5v, and Va/VS were spot on)? Not 100% sure how to proceed here.

Any thoughts?

-Jeff

[tom66]

Re: LG 60PG60 - Screen glows, but no top screen picture

Could you supply a picture of the TV with the back cover off, so we can see how it is arranged?

[jtieman]

Re: LG 60PG60 - Screen glows, but no top screen picture

Hello Tom,

Just shot a couple pictures.

First is back with cover off. Others are there to display symptoms.

As a side note, I did disconnect and re-connect all cables including the ribbons to the upper buffer board just to make sure it was making good connections. Same thing, no joy. Turned the set on with no upper buffer just to double check, and of course the top half of screen is 100% dark without it there, in the dark.

Thanks for your time,

-Jeff

[tom66]

Re: LG 60PG60 - Screen glows, but no top screen picture

OK, so this TV has a top address buffer. That's the long board running along the top. Can you get detailed, well lit pictures of it?

[jtieman]

Re: LG 60PG60 - Screen glows, but no top screen picture

Tom,

These are really not the finest pictures, but I hope they help. I did notice '12v' on some of the connectors, so I still need to check for 12v - I missed that before.

Let me know what you think, and again thanks for your help!


Jeff

[jtieman]

Re: LG 60PG60 - Screen glows, but no top screen picture

Well, I checked voltages at each connector on that top section of boards. All checked within spec, it appears. I did notice that those boards are powered in pairs - the left pair is connected to the y sustain and the right pair is connected to the z sustain. If I disconnect power from one pair at a time, it makes the corresponding section of the screen display a horizontal white bar, about 2 inches thick, across the middle of the screen. I would think that it would make the upper left or right quadrants white. Not sure if this information is helpful.

Thoughts, anyone?

Jeff

[tom66]

Re: LG 60PG60 - Screen glows, but no top screen picture

Do you have Va to both top boards?
I am thinking it's probably a top buffer board problem, but want to rule out the upper scan driver PCB.

[jtieman]

Re: LG 60PG60 - Screen glows, but no top screen picture

Yes, I have Va at all power connectors along the top.

[tom66]

Re: LG 60PG60 - Screen glows, but no top screen picture

OK what voltage do you measure across C123 in this picture, just right of the power connector?
https://www.badcaps.net/forum/attach...6&d=1409097197