LG 50PC3D-UD More problems....

[crbn79]

I decided to start a new thread since this appears to be another problem.

So far I have replaced bad Y-buffers, bad y-sus board, bad power supply.

I now run into a problem shown on the picture. I've read that it could be anything from a bad control board to bad y-sus.

I took some volt readings this morning and everything looks okay except the vsc which reads as low as 5v but should be 169v.

[tom66]

Re: LG 50PC3D-UD More problems....

It looks like you still have bad buffers.

[JonathanAnon]

Re: LG 50PC3D-UD More problems....

Have you checked the OSD with the remote to make sure the fault is not caused by the logic board or video board?

[crbn79]

Re: LG 50PC3D-UD More problems....

Have you checked the OSD with the remote to make sure the fault is not caused by the logic board or video board?

I don't have the remote, I did short out the OSD pin 1 and 2 and the individual colors, bars and lines all show properly.

Tom, I checked the buffer boards and showed no faults. I'm going to connect one at a time and see what I get.

[crbn79]

Re: LG 50PC3D-UD More problems....

It looks like you still have bad buffers.

I pulled both buffers and sure enough, they are both shorted AGAIN. This time I tested both buffers before installing them and they tested okay. What are the chances that my problems are being caused by the Y-Sus board?

I tested my VSC with no buffers hooked up and I get -169v and my -VY is showing +2.5v. It should be showing +120v on VSC and -200 on -VY.

From my power supply going to the y-sus my VA is 60v and VS 196v just as label on display calls for.

[tom66]

Re: LG 50PC3D-UD More problems....

-Vy is bad and this might have cooked your new buffers. Vsc is probably measured the wrong way around and is a little high, this is probably not a major issue (at the moment: you'd probably have sparklies on the image.)

[crbn79]

Re: LG 50PC3D-UD More problems....

-Vy is bad and this might have cooked your new buffers. Vsc is probably measured the wrong way around and is a little high, this is probably not a major issue (at the moment: you'd probably have sparklies on the image.)

What should I look for that would have the -VY so far off like that? Whenever I adjust the corresponding pot it only swings 1-2v with +2.5v being the lowest I can get it.

[tom66]

Re: LG 50PC3D-UD More problems....

You probably have a short on the Y-sus somewhere.

[crbn79]

Re: LG 50PC3D-UD More problems....

You probably have a short on the Y-sus somewhere.

That's what I was thinking. I tried to track it down and kept coming up with nothing. I decided to go back to my original Y-sus board, I replaced a couple of caps which looked like they were starting to swell a little. Then I hooked it up and I'm getting 120 VSC and -199.9 VY!

Now I think I'm back to buffer boards. I'm holding out hope that the Y-sus board only fried the FETs on them.