Plasma LG 50PS60 Screen Problem

[Brutis4555]

My 50" plasma LG TV's color goes out after having it on for a few minutes. It turns to light color with pink or purple hew. I know from reading other threads that I need to test the voltage on the different boards but I need help knowing where to test it and how much it should read.

Thank you in advance for your help!

[Caleb]

Re: Plasma LG 50PS60 Screen Problem

Concentrate on that board on the far right side. Known as the xsustain, failure will often appear as pink hue across screen.

[Brutis4555]

Re: Plasma LG 50PS60 Screen Problem

How do I test it?

[Caleb]

Re: Plasma LG 50PS60 Screen Problem

you might check the inductors down the center for poor soldering (on the bottom of the board), I recall lg had a problem with this previously.

[Brutis4555]

Re: Plasma LG 50PS60 Screen Problem

I have looked at that and I didn't find anything that looked out of place. Also I can leave the TV off for a long period of time and then it will work for a bit and then it goes bad again. Usually I turn the screen on and it is normal but goes bad within a minute.

[tom66]

Re: Plasma LG 50PS60 Screen Problem

Do you have a digital volt meter available to do tests with?

[Brutis4555]

Re: Plasma LG 50PS60 Screen Problem

Yes.

[tom66]

Re: Plasma LG 50PS60 Screen Problem

Do you notice any variation in how long it takes to go pink if the picture content is different?

For example, on the no signal display - does it last ages - and then on analog snow (not tuned) or normal TV it goes quickly?

For voltage checks, can you start by testing the Vs and Va voltages from the power supply. You can test directly at the connector. The negative lead of your multimeter can be connected to the chassis, and the positive lead should touch a Vs or Va test point, or on the connectors going to Y-sustain or Z-sustain (sometimes called X-sustain.)

[Brutis4555]

Re: Plasma LG 50PS60 Screen Problem

Can you dumb down what you are saying to check? I am not sure what you mean by those terms and I can't find any of my friends who do either.

[tom66]

Re: Plasma LG 50PS60 Screen Problem

Can you post a picture of your multimeter?
I just fixed a 50PS3000 with this fault. Same panel design as yours, minus a few features. It was a bad Vzbias circuit on the Z-sustain.

[Brutis4555]

Re: Plasma LG 50PS60 Screen Problem

Here you go. Thank you!

[tom66]

Re: Plasma LG 50PS60 Screen Problem

OK, you want to turn your multimeter to the 200 DCV range.
Then on the Z-sustain board, on the right hand side you will see a resistor marked VZBIAS

For guidance, see page 128 of this document
http://www.toms-service-manuals.com/...&Search=Submit

[Brutis4555]

Re: Plasma LG 50PS60 Screen Problem

Should I have the TV plugged in and on when testing it? Do I wait to test it until it has been on for 10 minutes?

[tom66]

Re: Plasma LG 50PS60 Screen Problem

Plug it in. You don't have to wait 10 minutes.

[Brutis4555]

Re: Plasma LG 50PS60 Screen Problem

Both rear 97.1 on the top and 97.2 on the bottom of them when it is plugged in but not turned on.

[tom66]

Re: Plasma LG 50PS60 Screen Problem

Sorry, meant plug it in and turn it on. See that it remains 97V. Then run it for some time, and when the tint occurs, see if the voltage drops.
Also check the Vs on the power supply.

[Brutis4555]

Re: Plasma LG 50PS60 Screen Problem

It went up to 180.

[Brutis4555]

Re: Plasma LG 50PS60 Screen Problem

The reading on the meter was 181.5 after the screen tint happened.

[tom66]

Re: Plasma LG 50PS60 Screen Problem

Wow, yes, that is definitely bad! Interesting, that the voltage increased on yours, but either way is bad. I had essentially the same problem on my set after replacing two transistors though mine only went to 150V, it made all black level a dark-yellow colour. I never saw a pink tint though..

Replace the transistor FQFP51N25 near the Vzbias point. I think it is Q13, but you should check. You need to replace it soon (and don't run the TV for too long), because if it continues for much longer, it will damage the other two transistors, complicating the repair.

[Brutis4555]

Re: Plasma LG 50PS60 Screen Problem

Ok, i see where it says Q13 but what do I need to change and where can I buy one?