LG 42PC3D-UE Plasma no video no screen glow.

[kevinm34232]

Owner said he hear a pop and sound still plays just no picture and I see screen does not glow. TV turns on and off normally, assume sound is there for now. One of the glass fuses on Y-SUS (FS2) is open shown in last pic. Any ideas? Rather large heatsink next door...

[1beertap]

Re: LG 42PC3D-UE Plasma no video no screen glow.

Check for shorted mosfets on the Y-SUS. Also, look for shorted buffers as shorted mosfets can sometimes take out a buffer chip. Maybe someone else can chime in on this.

[cliff_hootarski]

Re: LG 42PC3D-UE Plasma no video no screen glow.

I would suspect the IPM under the large black heat sink is shorted. Classic symptoms. Loud "Pop" , no picture with sound. Open fuse on Ysus.

[capkid]

Re: LG 42PC3D-UE Plasma no video no screen glow.

I would suspect the IPM under the large black heat sink is shorted. Classic symptoms. Loud "Pop" , no picture with sound. Open fuse on Ysus.

I agree. It's most likely the IPM on the Y-Sus. Check the Z-Sus's fuse, also. If it were my TV, I'd replace both IPMs, even if the Z-Sus's IPM isn't bad.

[kevinm34232]

Re: LG 42PC3D-UE Plasma no video no screen glow.

Just an update, it was the IPM on the YSUS that was shorted. I decided to try another board I for a reasonable price on ebay, the IPM and fuses were not shorted. I get same result. I have correct Va and Vs voltages. Is it possible the Y buffer is taken out by the the shorted IPM? The Z-Sus has no open fuses.

[tom66]

Re: LG 42PC3D-UE Plasma no video no screen glow.

Yes, and you may have damaged the new IPM by trying it with dead buffers.

[kevinm34232]

Re: LG 42PC3D-UE Plasma no video no screen glow.

Thanks Tom. Is there a way to test this buffer board? I looked at (your?) video on this

https://www.youtube.com/watch?v=51SZ...tCVe9&index=10

But not sure what pin to use on the Y-Sus side to check.

If it's bad will it always or usually show a short like that between Y-Sus output and the small ribbon pins?

[tw2005]

Re: LG 42PC3D-UE Plasma no video no screen glow.

I'm thinking between the largest copper pads(gnd) on P9,P11 and run the probe slowly along the buffer output connectors and see if anything is showing short in diode mode.

[kevinm34232]

Re: LG 42PC3D-UE Plasma no video no screen glow.

No apparent shorts on Y Buffer, is it possible that IPM is bad even if not shorted?

[kevinm34232]

Re: LG 42PC3D-UE Plasma no video no screen glow.

Is this where a scope would come in handy?

[tom66]

Re: LG 42PC3D-UE Plasma no video no screen glow.

Definitely.

[kevinm34232]

Re: LG 42PC3D-UE Plasma no video no screen glow.

Anybody had good luck removing these IPM's I've tried several ways it's a real PITA..

[tom66]

Re: LG 42PC3D-UE Plasma no video no screen glow.

Vacuum (powered) solder sucker works, but that's an expensive device.

[kevinm34232]

Re: LG 42PC3D-UE Plasma no video no screen glow.

$100+ from what I've seen.. haven't had a need for one up til now. I may have toasted this board with with the hot air..

[tw2005]

Re: LG 42PC3D-UE Plasma no video no screen glow.

This is primitive and brutal but the only way I had any luck was to get some desolder braid which was I happen to have used and long enough to run along the full length of the pins.
Flooded it with solder with a large 80W iron with a chisel tip and rand the iron back and forth to keep the solder flowing best I could whilst gently prying the IPM and crept it off a side at a time.

It is risky as you can

lift and tear off the pads and if it's anything like the 50PX5d IPMs it's double sided so you can tear a pad on the opposite side.

careful where you pry as there are usually nearby components that can be crushed.

Too much heat and the board can start delaminating.

The first board I did I had to use a track repair kit to fix the damage but it did have the IPMs removed 3 times before we got it sorted. Well and truly cooked the board

The next 2 boards went much better with the experience.

EDIT: Hot Air.Yes we tried that (Heat Gun in fact) but the heat was drawn away from the pins so much that the board delaminated. Makes a nice cracking sound. Still used the board and it worked. that's the first one with the track repair. It copped a lot of abuse before we got the IPM off.
I'm sure there's smarter ways but tools were limited.

[kevinm34232]

Re: LG 42PC3D-UE Plasma no video no screen glow.

Thanks for the info..

Also is there is a video test pattern for this TV?

[tw2005]

Re: LG 42PC3D-UE Plasma no video no screen glow.

Have you had a look at the reference library sticky? Tom has created a website with a library of manuals.

http://www.tgohome.com/ServiceManuals

http://www.tgohome.com/ServiceManual.../LG_42PC3D-DC_[SM].pdf

Most TVs have some kind of inbuilt generator.

I think with the LG there's a service remote needed to get into the adjustments but there is another but I can't remember clearly but I suspect holding Menu button on the TV and pressing menu on the remote at the same time.

A bit of googling or searching in these forums will unearth something. That's how I found it.

[tw2005]

Re: LG 42PC3D-UE Plasma no video no screen glow.

https://www.badcaps.net/forum/showthread.php?t=24809


LG/Zenith:
Hold MENU on TV and MENU on remote for 5~10 seconds

[kevinm34232]

Re: LG 42PC3D-UE Plasma no video no screen glow.

I forgot about ChipQuik, I used this to flood the pins of the IPM and with a combo of soldering iron on max power and then hot air over the pins it came out 'relatively' easy. I had 3 different boards with these IPM's, one I know is shot now, the 2nd is questionable, but the 3rd one looks real good.

The first one I tried (questionable one) I wound up using a hacksaw blade and sawed out the module but sawed a couple other components too (: We'll see if it works again..

[kevinm34232]

Re: LG 42PC3D-UE Plasma no video no screen glow.

Ok got this new IPM in and now I get a picture (haven't hooked to a source yet) but getting red speckles thru the screen, I've seen this posted before recently I think.. Is this a seperate issue or do I need to adjust voltages?

Vs and Va are good