Lg plasma 50px5d-bad picture, washed out, no colour

[tw2005]

I've picked up a LG 50PX5D from a mate who's given up. Then found another hoping to make one from 2. He did attempt replacing the modules but shorted something out.

It has a very washed out picture with no colour and very pale blue appearance.

If I go into the menu and select the white wash it will produce a white display which looks fairly normal.

Both IPM's on both zsus and ysus are buzzing away and mildly warm.

I've swapped buffers between the sets and same result so I'm thinking it's on the ysus board.

Like to repair at component level and need some help.

I have not seen this type of display fault before.

[tw2005]

Re: Lg plasma 50px5d-bad picture, washed out, no colour

Ok, I think I've worked out what's going on. Looks like whoever worked on the donor set went to the extreme and has shifted all the adjustment pots on the ysus.

They also broke off 2 locking tabs on the upper buffer. Butcher!

I bet I need several things to fix this.

1. Experience
2. Oscilloscope
3. Data

I'm out of luck on all 3! Any suggestions?

[tom66]

Re: Lg plasma 50px5d-bad picture, washed out, no colour

You should adjust all pots to the correct rating on the panel sticker. Pictures would help!

[tw2005]

Re: Lg plasma 50px5d-bad picture, washed out, no colour

It's not the panel voltages that are the problem. Pretty straight forward setting them with a DMM.

It's the YSUS waveform /timing setup that's been messed with. Pretty sure you should not mess with these but they have been moved.

Tried measuring the pots on the dead ysus but suprisingly ended up with the original bad picture.

VSET_UP, RAMP_UP,VSET_DN

[tw2005]

Re: Lg plasma 50px5d-bad picture, washed out, no colour

Well I've done my best and the picture's ok. I think the hardest thing with these is that it's no youngster anymore and probably fighting with an aged panel.

What I've done thanks to the Shopjimmy website is they photograph the boards well enough to get some good detail.

Both the A & B revision boards have the pots set in the same position so thanks to the marker on the pot I've set mine as close as I can tell.

I don't like working on the LGs much but fantastic sound out of this set.