LG 60PC1D Z-SUS Board question

[jcmccorm]

Hi folks, I've got a question about the Z-sustain board on my LG plasma.

First off, first post and I'd like to offer many thanks for the knowledgeable people here that have helped me get this far with this TV.

I was able to diagnose the problem with my TV as the Z-sustain board (thanks to this forum). I ordered a replacement online and had no trouble replacing the board. I fired it up and everything worked (back to normal) for about 2 minutes. There was a loud pop and the TV shut off. I turned it back on and it retried several times before remaining powered off. I imagine the power-supply sensed a short. The Z-sustain board's fuse was still ok though. I tried powering up again and after a few attempts, it was successful but now the image had the same symptoms as before replacing the z-sustain board. The fuse on the z-sustain board was now open.

So, now my new (well, refurbished) z-sustain board is bad. My question is this; is there something that's feeding this board causing it to fail? Or, is it more likely that there's something else on the z-sustain board that is bad that wasn't caught by whomever performed the repair on it?

How hard is it to repair these? I'm an electrical engineer and have access to and experience soldering. I just don't know how these TV's work

Thanks for any help!

Cary

[Alastair E]

Re: LG 60PC1D Z-SUS Board question

Sounds like an IPM failure on Z-sus board--They go with a loud pop--like bubble-gum, but MUCH louder.........

The Y-sus supplies a couple of 15V rails--its just possible a low 15V supply could take out an IPM.--Usual cause is one of the small S.M. caps in the small-supply inverter of Y-SUS--just replace 'em all. 33uF and 100uF as I recall....

--Either way, you need another Z-SUS or find/replace the faulty IPM on your board. Does it have 2 or three on that one?

[jcmccorm]

Re: LG 60PC1D Z-SUS Board question

Thank you for the reply!

This Z-SUS board has two IPMs. One of which I assume is the energy recovery?

I see a cable connecting the Y-SUS and Z-SUS with silkscreen indicating that it carries Vs, Va, GND, and +5. Are Vs and Va the 15V rails or are they somewhere else? What should Va and Vs be?

Thanks again for the help!

Cary

PS. Doh. I found the sticker - Va=60V and Vs=193V. I can check these. I'll still need to find where the 15V rails are and verify the voltage (+/-15V I assume).

[tom66]

Re: LG 60PC1D Z-SUS Board question

15V comes in from the control board, if I remember correctly.

[jcmccorm]

Re: LG 60PC1D Z-SUS Board question

Thanks Tom, I'll check that as well as Va and Vs when I get back from work.

What/where is a good source for the IPM devices?

Cary

[jcmccorm]

Re: LG 60PC1D Z-SUS Board question

I checked Va and Vs and got 193.0V and 60.5V respectively. Looks like I'm ok there. I checked a few other (lower) voltages coming off of the power-supply board and they are all ok. I'm going to chalk this up to a bad refurbish job on the Z-SUS board (maybe there was a bad diode on the board as well). I'll try my luck with another Z-SUS board. Anyone have a recommended source for these? Or the IPMs themselves? Thanks!

Cary

[jcmccorm]

Re: LG 60PC1D Z-SUS Board question

Ok, not to beat a dead horse, but this is starting to cost real money

I installed my second replacement Z-SUS board into this TV and I got about 30 minutes out of it before the IPM popped again.

What am I missing here? What could kill the Z-SUS besides bad Va or Vs? (both are spot on).

Thanks!

Cary