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**PlainBill** · 04-14-2011, 09:09 PM

Re: lg 42pc3d has sound no picture and no backlight

Originally posted by cadillacman View Post

Hey guys fresh project here..

its a 42" lg plasma, model 42pc3d.

When powered on, had sound but no pic and no backlight.

Took it apart, a quick check showed a blown fuse ont he y-sus board.

I replaced the fuse, then the tv would power on then shut back off.

Unplugging the ysus power connector woul dlet the tv powerup and stay on.

Reconnected the ysus and the tv stayed on this time.

rechecked and that same fuse blew.

I would assume while the fuse was still good the power supply saw something it didnt like and was shutting it down.

SO basically, i have an issue with the ysus board.

I found this "repair kit" on ebay, that consists of one fuse and a hybrid module????

if thats a good deal ill definately give it a shot. I am great at desoldering and soldering so if thats what it is i dont see myself havign an issue with it.

SO lmk if you think im headed in the right direction and ill go for it. Or if you happen to have a good ysus board, lmk.

mike

There are a couple of issues here. First of all, you have definitely established the problem is the Y-sustain. Replacing the hybrid is a real PITA. I've done it twice, and wound up batting 500. One person reported that by breaking the tabs on the hybrid he was able to remove the heat sink, then cut the pins on the dead hybrid, and pull it that way.

Someone else mentioned using the old soldering irons used for metalworking (think a 3/4" square block of copper about 3" long). He'd hacksaw a groove along one side, heat the iron up with a torch, and fill the groove with molten solder. Apply that to a row of pins and that side of the hybrid comes right out. Repeat for the other side.

There is also the issue that there may be another problem that caused the hybrid to fail.

I suggest reading this thread for more information.

PlainBill

**cadillacman** · 04-14-2011, 09:16 PM

Re: lg 42pc3d has sound no picture and no backlight

As always plainbill you come through with a wealth of information. THANK YOU. seriously.. I think alot of folks here ignore me because im a newb and hey i understand, but i can also tell you this: im not going anywhere heh..

THanks for the info, ill give it a read, and thanks again for always replying to my posts i do appreciate it man.

**cadillacman** · 04-15-2011, 11:46 PM

Re: lg 42pc3d has sound no picture and no backlight

Hey i just had a lightbulb moment..

i have some very small square 12v fans...

bieng these lgs are absoultely notorious for puking these hybrid ics, do you think it would be a good idea to add a fan under each ic blowing upward on the heatsink?

well upward ont he ysus, and probhably on top pulling ther air up on the other board as theres no room for it underneath. These fans are small but move alot of air. I used to add them to car amps all the time to help them run cooler.

do you think the ps could handle a small load from these fans?

**PlainBill** · 04-16-2011, 07:42 AM

Re: lg 42pc3d has sound no picture and no backlight

There are a couple of points I want to make.

Plasma TVs have no backlights. The picture elements in the plasma panel generate light in the proper colors directly.

The likely cause of failure is not the temperature of the heat sink, but the heat transfer from the hybrid to the heat sink.

The design of these boards is a disgrace. Samsung uses a similar arrangement, but has holes in the board so the heat sink can be removed easily.

I don't think a fan is necessary, but go ahead. The power supply may have legends indicating the output voltages and current ratings.

PlainBill

**cadillacman** · 04-16-2011, 01:05 PM

Re: lg 42pc3d has sound no picture and no backlight

Originally posted by plainbill View Post

there are a couple of points i want to make.

Plasma tvs have no backlights. The picture elements in the plasma panel generate light in the proper colors directly.
( aha thank you, im such a newb lol)

the likely cause of failure is not the temperature of the heat sink, but the heat transfer from the hybrid to the heat sink.

The design of these boards is a disgrace. ( i agree man!!)
samsung uses a similar arrangement, but has holes in the board so the heat sink can be removed easily.

I don't think a fan is necessary, but go ahead. The power supply may have legends indicating the output voltages and current ratings.
(yeah i will do some poking aroundd and see what i can see...)
plainbill

123456

**cadillacman** · 04-20-2011, 08:39 PM

Re: lg 42pc3d has sound no picture and no backlight

My new hybrid came in today from canada. Heading down to the basement in a few mins to put it in. Wish me luck!

**cadillacman** · 04-20-2011, 10:17 PM

Re: lg 42pc3d has sound no picture and no backlight

WELL, i am about 98% there..

it powers up, makes a pic, has all the colors BUT:

i have red snow lol. I guess you could also call it sparkles, speckles, whatever.

More dense in a horzontal fashion along the bottom, but if im sitting on a black screen with the "no signal" bar bouncing around, after the bar moves a dense cluster os red sparkles are where the no signal bar juat was, if that makes sense.

Please tell me theres some adjustment or something simple for this. It kills me to be this close and just not quite on.

**PlainBill** · 04-21-2011, 04:35 AM

Re: lg 42pc3d has sound no picture and no backlight

Originally posted by cadillacman View Post

WELL, i am about 98% there..

it powers up, makes a pic, has all the colors BUT:

i have red snow lol. I guess you could also call it sparkles, speckles, whatever.

More dense in a horzontal fashion along the bottom, but if im sitting on a black screen with the "no signal" bar bouncing around, after the bar moves a dense cluster os red sparkles are where the no signal bar juat was, if that makes sense.

Please tell me theres some adjustment or something simple for this. It kills me to be this close and just not quite on.

There are adjustments, but one in particular is not simple. Download LG's alignment handbook frm Elektrotanya.

Perform the setup directions for your panel in order.

PlainBill

**cadillacman** · 04-21-2011, 11:19 AM

Re: lg 42pc3d has sound no picture and no backlight

wow that is AWESOME info!! Heres to hoping i can adjust it out. Time to break out the old scope!!

**cadillacman** · 04-23-2011, 06:16 PM

Re: lg 42pc3d has sound no picture and no backlight

well, i got it alot better-----

but i still have sparkles.

Pretty sure somethings wrong with the ysustain or buffers as when im adjusting the pots on the y -sustain the issue gets better/worse so im in the right area i think..

**cadillacman** · 04-23-2011, 09:20 PM

Re: lg 42pc3d has sound no picture and no backlight

got real lucky and found another dead tv same model( well its a 42pc3d V )

wish me luck! It better have a frickin good ysustain and buffer in it!!

**cadillacman** · 04-23-2011, 10:05 PM

Re: lg 42pc3d has sound no picture and no backlight

got lucky here.. the set i just picked up is in super super nice shape.. with a blown hybrid and mabye more on the z-sus board.. power supply and y-sus check ok!!

So i pulled the good z-sus board from the set i posted about originally and put it in the new set i just picked up..

I hope to one day get another set this model or a set of boards or whatever and get back to the fixing the set i posted about originally.

For now, im happy i built one out of two and learned alot along the way.

I should be swapping parts into the other set to figure out what my res sparkle issue is, but im araid ill blow something and have two dead sets instead of one..

and an interesting sidenote: i have an older(2003 model) lg plasma same size that i will be posting about soon.

.IT.CAME.FROM.THE.FACTORY. with fans on the hybrids... hmmm makes me wonder why they stopped doing it!!!! Probhably cost cutting or something stupid..

**Rider1** · 04-24-2011, 09:59 AM

Re: lg 42pc3d has sound no picture and no backlight

Hello,
I am new to this site and I have the same problem with my 42pc3d. I know enough to be dangerous so I opend up the tv and noticed some leaking caps on the top upper board. I went to the local store and purchased a handfull of 10v caps and replaced them. Didnt make a difference. I searched on the internet and thought the problem was the Z sustain board. bought one from Ebay for $85.00 and replaced it. No difference. I spent $50.00 and had a TV repair guy look at it and he said it was the Y Sustain board. Wich board is the Y Sustain board and could I have fouled up the other board by replacing the 10v caps?
I would appriciate any feedback. Thank you.

**cadillacman** · 04-24-2011, 06:48 PM

Re: lg 42pc3d has sound no picture and no backlight

as long as you replaced the caps with some quality, low er caps of the SAME UF VALUE AND VOLTAGE and installed them in the correct orientationm youre ok.

DO you have a digial multimeter? Check the fuses on all the boards. usually when the ysustain goes it will pop one of the fuses.

when i fixed my original ysustain boards, i replaced the big hybrid (from that ebay link i posted earlier) and that got the ysustain going again.. as posted this set does suffer some red sparkles i am unsure if i have a different issue with the ysustain or if its a buffer issue or something else..

i will find out the next time i have another tv of this model here.

You can get that hybrid cheaper- at the time i has to destroy my old hybrid so i couldnt get the part nubmer from it- so i got the $40 kit off of ebay. WHen i got my new one i wrote that number down so if you want i can find that and post it here. you can get the hubrids by themselves elseware from $20-30 and a fuse is only a few bucks.

Unless you are VERY good at desoldering and have a super super hot iron i would suggest mabye doing a service like this:
for like $65 they will exchange your dead ysustain board for a good rebuilt one..

http://cgi.ebay.com/Sustain-6871QYH0...item5ad9a71c41

http://cgi.ebay.com/6870QYH005B-LG-4...item19bc72c49d

heres the "repair kit" i was talking about
http://cgi.ebay.com/Sustain-6871QYH0...item5ad9a71c41

Best of luck! If you ever give up on it, i would be interested in all the boards out of it dead or alive.

**rayrod81** · 04-24-2011, 11:34 PM

Re: lg 42pc3d has sound no picture and no backlight

The red sparkles are caused by the firmware on the control board. These will not go away no matter how well you adjust the voltages. Only a firmware update will fix this issue and you need a special programmer from lg to do it. If you can get past the sparkles it causes no harm nor signifies any major problems with the tv.

**cadillacman** · 04-25-2011, 12:21 AM

Re: lg 42pc3d has sound no picture and no backlight

so... if i could obtain a NEW control board, would it have the fix in it?

could be i make this my arcade room tv or something...

**rayrod81** · 04-25-2011, 08:22 AM

Re: lg 42pc3d has sound no picture and no backlight

Its possible that it would fix it but I am not sure. I have access to the equipment to fix this issue and haven't tried a new control board. Most of the 42" LGs that I have worked on have had this problem but some have been fine.

**cadillacman** · 04-25-2011, 08:32 PM

Re: lg 42pc3d has sound no picture and no backlight

i wish i could find somebody locally who would do it. It would be worth throwing the tech some $$$ under the table sort of speak if it would be done.

What i dint understand is why it didnt sparkle new and now it does that its old, but the firmware thats always been the same it at fault? i guess i dont get it.

**rayrod81** · 04-26-2011, 09:56 AM

Re: lg 42pc3d has sound no picture and no backlight

It is just due to the slow breakdown of the components and the control board just needing a slight calibration to handle this issue. It is a pain because it shouldn't need to be adjusted but that is the nature of the 42" LGs I guess.

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