LG 42pc1dv picture gone

[oggy]

Hi. Picture gone on an LG 42pc1dv-ec plasma. Sound OK, inputs OK.
Vs fuse blown on y-sus board. Replaced it but still no pic.

Checked voltages from PSU when switched on from cold.
Vs>300v Va>80v. Label says they should be Vs=185 and Va=60.
Noticed voltages slowly dropped to about their correct levels after 20 mins.
Is this normal as the set warms up ?

Read that the y-sus can give problems on these models.
The replaced fuse has not blown again so now I am confused (no pun intended)!
Only a novice so any help appreciated. Thanks.

[brainstorm]

Hi Oggy,

I had one of these models  last week with one of the fuses blown but it displayed a very poor picture,
I didnt try replacing the fuse because it was reading 15 ohms to earth.
I replaced the board and the set worked fine.

Hope this helps

Brian

[oggy]

Hi Brian, thanks for the reply.
It's just that I'm trying to rule out the PSU before I go for the y-sus. Don't want to spend over £100 for a ysus and find its the PSU !!
Regards, Malc

[norman]

Hi Malc, I have just repaired one of these, the y sustain board was faulty. If the VA & VS voltages take about twenty minutes to come down then I suggest you have a psu fault as well. It may be the high voltages has damaged the y sus board. Try heating and freezing capacitors in the psu to see if there are any substantial change in VA & VS voltages. Hope this helps you, Norman

[oggy]

Hi Norman. I've solved the high voltage problem.
It was a faulty digital multimeter and now all the PSU
voltages check out OK, as well as the -Vy and Vsc on the
Y-sus board.

One time when I was swithching the set on I noticed a spark
come from one of the FET's on the small heatsink on the Y-sus.
Read from LG training manual on the net that these can fail.

Has any body tried checking and replacing these 5 FET's and
got the picture working again ?
Also noticed the large heatsink on Y-sus is not getting warm,
like the others. Don't Know what's underneath it but guess
that's not working too !

Thanks for the help,
Malc.

[norman]

Hi Malc, It is a hybrid ic under the heatsink, these fail regularily. When the ic is working it is very hot. It is not usually worthwhile trying trying to repair the board as the ic is not available. You will need to bite the bullet and buy a new board or scrap the set. Cheers, Norman.

[oggy]

Thanks Nornan. Looks like it's a new or second-hand board then.
There are 2 different part numbers on the y-sus board.
One is etched on (6870QYH005B).
One is on a label (6871QYH048B).
I can't seam to find many boards on the net with both these
numbers identical to mine.
Do you Know if there are any compatible y-sus boards for
the LG 42PC1DV-EC ?
Can you tell me where you managed to obtain yours from ?
Cheers, Malc.

[norman]

Hi Malc, use the numbers on the label. I got my board from SEME NEDIS it is listed at £86.50 +vat, no stock. Charles hyde and son also list it at £120 +vat, no stock. Nikko Electronics list it at £115 +vat and I think they have them in stock they are also known as Dalbani. I hope this helps, Norman

[oggy]

Hi Norman. Yes, I found most of them out of stock too.
There's no rush so I may wait and see if a cheap one
turns up on ebay first, before I go for a new one.
Thanks again for all your help,
Malc.

[civlov]

mine has gone due to water ingress, when you turn the set on you get a mad rush of colors,thent the screen goes black, with fifferent colored spots and then you get massive white lins moving left across screen? would this be the y sus?

[tv tony]

hello all, it could be the lower drv pcb, remove and check with the pcb removed