60PV250-UB Mal Discharge after warm-up / 30 minutes.

[NSchober]

I have read much of information about plasma T.V.s over the past few weeks. I have also searched endlessly for a service manual for this model LG T.V., to no avail. I have found some things that are useful but I can't seem to stop this issue from happening. I have checked all my Voltages pre and post Mal and they match the sticker.

I have included pictures of the symptoms. The one that is in color is the precursor to the black one. 2-5 seconds before my screen loses all color I get that ghosting / color splash. Then I lose all color and get that gray-scale image. Before the set warms up the picture is beautiful and everything functions great.

I have taken out the Z and Y sus boards and re-flowed the joints even though they looked fine, I have also done the same to the power board. Besides some slight discoloring and lots of dust, the boards all looked fine.I have included images of the reverse of the Zsus, Ysus, and power.

I am at a loss and would appreciate any assistance with this. Please let me know of any and all information you require to assist me in this trouble shoot. Please keep in mind that I am an amateur and not really sure what I am doing. This is a bit different than the control systems I am used to.

[tom66]

Re: 60PV250-UB Mal Discharge after warm-up / 30 minutes.

My best guess is this is your Vzbias voltage going bad for some reason.

It could also be another voltage like -Vy, Vsc or possibly even Va, though the latter is unlikely.

What you can do is take measurements of all of these voltages when the set works.

Then when the set has failed, take the measurements again and note any changes.

If you need advice on where to find the voltages for your set, post a picture of your "panel sticker". It's the sticker inside the TV on the back of the plasma panel, it'll have a part number like "LG Electronics PDP60X9######" printed on it, along with some voltages. We need the sticker to tell you the voltages and find the service guide for your particular PDP module.

Note: When you put the boards back in the TV ensure you fit ALL screws, failure to do so may cause the boards to fail prematurely as screws are used as part of the ground path.

[tw2005]

Re: 60PV250-UB Mal Discharge after warm-up / 30 minutes.

when you reflowed the ZSUS, were the solders on the 3 large inductor coils reflowed?

[NSchober]

Re: 60PV250-UB Mal Discharge after warm-up / 30 minutes.

It looked like it may have been, but I don't know. I was given this T.V because it is "broken". The coils looked good, with no cracking or discolor.

[NSchober]

Re: 60PV250-UB Mal Discharge after warm-up / 30 minutes.

My best guess is this is your Vzbias voltage going bad for some reason.

It could also be another voltage like -Vy, Vsc or possibly even Va, though the latter is unlikely.

What you can do is take measurements of all of these voltages when the set works.

Then when the set has failed, take the measurements again and note any changes.

If you need advice on where to find the voltages for your set, post a picture of your "panel sticker". It's the sticker inside the TV on the back of the plasma panel, it'll have a part number like "LG Electronics PDP60X9######" printed on it, along with some voltages. We need the sticker to tell you the voltages and find the service guide for your particular PDP module.

Note: When you put the boards back in the TV ensure you fit ALL screws, failure to do so may cause the boards to fail prematurely as screws are used as part of the ground path.

I have done this Tom, but I will do it again and post results.

[NSchober]

Re: 60PV250-UB Mal Discharge after warm-up / 30 minutes.

Power supply:

Va - Pre: 55 Post: 55
Vs - Pre: 201 Post: 201

Ysus:

-Vy - Pre: -178 Post: -178
VSC - Pre: 153 ~adjusted to 150~ Post: 148


Zsus:

VZB - Pre: 111 ~adjusted to 110~ Post: 98

[NSchober]

Re: 60PV250-UB Mal Discharge after warm-up / 30 minutes.

I used a hair dryer to pin point this location on my Z-sus board. If I heat this area I lose picture. If I then cool this area and restart the T.V. I get the picture to come back.

[mmartell]

Re: 60PV250-UB Mal Discharge after warm-up / 30 minutes.

Do the test again but with the straw attached to a can of compressed air. That way you can find the specific component that's causing the problem.

[NSchober]

Re: 60PV250-UB Mal Discharge after warm-up / 30 minutes.

Do the test again but with the straw attached to a can of compressed air. That way you can find the specific component that's causing the problem.

I will try this tonight.

[NSchober]

Re: 60PV250-UB Mal Discharge after warm-up / 30 minutes.

Double post.

[tom66]

Re: 60PV250-UB Mal Discharge after warm-up / 30 minutes.

Interesting fault, might be an issue with the solder around some of those IGBTs, or possibly a failing IGBT.

The Vzb changing is very odd though. How specific is the heating? Do other areas cause the symptom to come but more slowly? or not at all?

Will await compressed air tests, may indicate exact part.

[NSchober]

Re: 60PV250-UB Mal Discharge after warm-up / 30 minutes.

Sorry Gents, I had to work a double tonight and was unable to purchase the compressed air. I will attempt the test on the morrow.

[NSchober]

Re: 60PV250-UB Mal Discharge after warm-up / 30 minutes.

I purchased a can of canned air (Duster) to continue trouble shooting. In the meanwhile I received a rebuilt Zsus from Ebay. I have replaced the Zsus and have had no issues since. I have mosfets on order from China, so when they arrive I will continue the troubleshooting with the Duster and install them on the board. I will then post my results so as to complete everything at once.