LG 60pv250-tb ..Z sus issue

[DanDontknow]

Hello I have a 60" Plasma Lg
The Screen is purple and slow to get the picture when turned on
I started searching this site and have found a lot of useful information
I removed the z sus board and fixed the broken solder joints on the coils.
I checked the powers as per the sticker
I checked the fuses on the boards and found high o/c on the vs for the Z sus
I replaced the fuse and now it wont turn on.
I removed the cables to the z sus board and the control board boots up
so I removed the fuse and I still have the original problem.
I am guessing control board wont boot because there is a further problem with the the Z sus board ( the fuse for the VS has not blown again.)
I have tried looking for the board online and its not as easy or as cheap to find as I had hoped. I would like to repair the board if possible.
Where should I begin.
Thanks Dan

[sordids999]

Re: LG 60pv250-tb ..Z sus issue

Posting pictures of the back of your tv showing the boards with clear pictures may help you more with fixing your problem

[Alastair E]

Re: LG 60pv250-tb ..Z sus issue

You'll need to pull the Z and check all the IGBT's etc for shorts.

You'll probably find 4 to 8 of them short and possibly some diodes and maybe the driver chips too....

[DanDontknow]

Re: LG 60pv250-tb ..Z sus issue

Thanks for the replys, Is there anyway to read the control board to find out what is stopping it from booting or should I just start checking everything on the z sus board.
Cheers Dan

[DanDontknow]

Re: LG 60pv250-tb ..Z sus issue

Picture of the Z Sustain board as viewed from the back of the tv fitted to the top right.

The fuse holder I fitted is for ease as removal only

[DanDontknow]

Re: LG 60pv250-tb ..Z sus issue

Picture of the Z Sustain board .
Rear of board--Imaged flipped to match circuits easier on pics

[DanDontknow]

Re: LG 60pv250-tb ..Z sus issue

I will be playing with the board tomorrow
Does anyone know if I can isolate different parts of the board by removing the least amount of components to check for shorts.
or the most likely section to start with for a short on the vs power
which igbt to remove first.
Thanks Dan

[tom66]

Re: LG 60pv250-tb ..Z sus issue

You would want to focus on removing the IGBTs in the SUS path - the ones connected to Vs or GND. A Z-sus only has one bias path (the Vzb section) - that's probably OK - it's usually formed of two back-to-back MOSFETs. There's also an energy recovery section which is also probably OK.

[DanDontknow]

Re: LG 60pv250-tb ..Z sus issue

Thanks Tom

[DanDontknow]

Re: LG 60pv250-tb ..Z sus issue

Update
I have de-soldered the IGBTs and found 4 shorted
I have checked the board now
what would be the acceptable ohms reading between the ground and the Z sus path
I have
144kohms between ground and the fuse
670kohms between ground and the 3 plugs on the right.

[tom66]

Re: LG 60pv250-tb ..Z sus issue

That looks OK to me

[DanDontknow]

Re: LG 60pv250-tb ..Z sus issue

Thats good to here.
Looking online for the IGBTs FGPF4633
I can find some from china on ebay but not sure I would trust them.
or locally would any of these match
http://www.altronics.com.au/electron...ation_2=mosfet

http://www.jaycar.com.au/search?q=fe...211C&text=fets

These stores are similar to maplins

if not where is the best place to order from.
Thanks Dan

[bruceleeworldwide]

Re: LG 60pv250-tb ..Z sus issue

Hi, Alastair E

This is very good information, I read it thoroughly but I could not get clear still. For example, there are 5 voltages on y board of lg60pv250, +Vsustain, Vsc, V-xy, Vset up, Vset down while there are only 3 (+Vsustain, +Vset, -Vreset) in Figures . Can you pls tell me more how to match them? I am interested in it. …Why isn't there the Vscan?
Thank you.
Bruce