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Old 07-04-2010, 11:35 PM   #1
ub6ib969
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Default LG 42PC3D-UE plasma: no picture.

Here is my dilemma. I have a LG 42PC3D-UE and lost my picture but still have sound. Now it seems that alot of these LG TV's have the same problem. What I have done is disconnect the power the the ZSUS and the tv powers on without sound of course, but when I disconnect the YSUS board and connect the ZSUS board the TV clicks on then off. Now the interesting thing is when I disconnect the both boards the TV powers with only sound. So what is did remove the fuses (from the ysus and zsus 4 in total) and checked them and found that one was open. The problem is I mixed up which fuses came from which board So I just replaced the open one and inserted them back in the clips. I still got the same result, but now I have a bit of smoke coming out from the top left corner of the control board! Previously I didn't have this problem only when I replaced the new fuse. I also just wanted to add that after running the unit for 15 min I found that the ZSUS was cold and the YSUS was warmer. I also checked the voltage going to the boards and it all checks out. Any help would be great!
-Thanks

Last edited by ub6ib969; 07-04-2010 at 11:38 PM..
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Old 07-05-2010, 06:48 AM   #2
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Default Re: LG 42PC3D-UE plasma: no picture.

Quote:
Originally Posted by ub6ib969
Here is my dilemma. I have a LG 42PC3D-UE and lost my picture but still have sound. Now it seems that alot of these LG TV's have the same problem. What I have done is disconnect the power the the ZSUS and the tv powers on without sound of course, but when I disconnect the YSUS board and connect the ZSUS board the TV clicks on then off. Now the interesting thing is when I disconnect the both boards the TV powers with only sound. So what is did remove the fuses (from the ysus and zsus 4 in total) and checked them and found that one was open. The problem is I mixed up which fuses came from which board So I just replaced the open one and inserted them back in the clips. I still got the same result, but now I have a bit of smoke coming out from the top left corner of the control board! Previously I didn't have this problem only when I replaced the new fuse. I also just wanted to add that after running the unit for 15 min I found that the ZSUS was cold and the YSUS was warmer. I also checked the voltage going to the boards and it all checks out. Any help would be great!
-Thanks
Out of a sample of 3, the common cause of the 'sound but no picture' problem was a faulty Z-sus. This could be repaired either by replacing the Z-sus (easy), or by replacing the hybrid on the Z-sus (cheaper, but not so easy). Since you pulled the fuses rather than checking them in place, it appears both the Y-sus and the Z-sus may have been bad. Also, it appears you have damaged the control board in the process.

I suggest there are may uses for your plasma TV. It can be converted to a picture frame; you can use it as a reminder to be more careful, or you can give it away as a 'staging prop'. You may even be able to sell the power supply, and the plasma panel to recoup some of your loss. In my opinion, it's not worth repairing.

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Old 07-05-2010, 10:57 AM   #3
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Default Re: LG 42PC3D-UE plasma: no picture.

Thank you PlainBill for your reply. Was removing the fuses from the clips a mistake? Now once it powers on the TV stays on but smokes a little. I really don't want get rid it.
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Old 07-05-2010, 11:37 AM   #4
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Default Re: LG 42PC3D-UE plasma: no picture.

Quote:
Originally Posted by ub6ib969
Thank you PlainBill for your reply. Was removing the fuses from the clips a mistake? Now once it powers on the TV stays on but smokes a little. I really don't want get rid it.
Removing the fuses from the clips wasn't a mistake; losing track of where they came from was.

Consider the situation initially: Something was loading the power supply so it would not come up. Disconnecting the Z-sus allowed it to power up. Clearly the Z-sus was part of the problem. The lack of sound complicates matters - the sound should have still worked. Now you have stated there is smoke coming from the 'control card'. I'm not sure you are referring to the card with the input jacks (often referred to as the small signal card) or the main control card, hidden behind the small signal card.

Unless your soldering skills are much better than your troubleshooting skills, you will have to replace (or have someone repair) the Z-sus and probably the Y-sus cards. I note someone is doing this for $75 a board. The main logic card and the small signal card are each $75. At a minimum, you are looking at $150; the cost to repair can be more than double that if the Y buffers are bad.

What is even worse, you will need an oscilloscope to set up the Y card properly.

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Old 07-05-2010, 12:13 PM   #5
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Default Re: LG 42PC3D-UE plasma: no picture.

"no user serviceable parts inside"
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Old 07-05-2010, 01:10 PM   #6
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Default Re: LG 42PC3D-UE plasma: no picture.

Quote:
Originally Posted by PlainBill
Removing the fuses from the clips wasn't a mistake; losing track of where they came from was.

Consider the situation initially: Something was loading the power supply so it would not come up. Disconnecting the Z-sus allowed it to power up. Clearly the Z-sus was part of the problem. The lack of sound complicates matters - the sound should have still worked. Now you have stated there is smoke coming from the 'control card'. I'm not sure you are referring to the card with the input jacks (often referred to as the small signal card) or the main control card, hidden behind the small signal card.

Unless your soldering skills are much better than your troubleshooting skills, you will have to replace (or have someone repair) the Z-sus and probably the Y-sus cards. I note someone is doing this for $75 a board. The main logic card and the small signal card are each $75. At a minimum, you are looking at $150; the cost to repair can be more than double that if the Y buffers are bad.

What is even worse, you will need an oscilloscope to set up the Y card properly.

PlainBill
Thanks for the reply. The smoke is coming from the board which has the power going to ZSUS and YSUS board. Its in the middle between both of cards. We'll it turns out that when I disconnect the ZSUS board the tv turns on with sound but you can here something lighting up where the main control board is and smoke appears. When i disconnect the ysus board the the clicks on then off instantly.
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Old 07-05-2010, 01:26 PM   #7
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Default Re: LG 42PC3D-UE plasma: no picture.

Ahhh, I see good smoke only when grilling food. Plainbill is correct. Once you lose track of the fuses and you power the board up, lol, wow... dude.... seriously? The set will now have too many parts that need replaced to make it worth repairing. If you are doing this for a hobbie, I'd suggest reading a few books first. Blindly going into your set has rendered it useless - "Picture Frame" at best. Putting too much money into this is not wise. Even if you get it working with replacement boards, who's to say it will last?
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Old 07-05-2010, 01:57 PM   #8
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Default Re: LG 42PC3D-UE plasma: no picture.

Here's what I would do: Look on ebay and other areas for an identical unit that turns on but has a broken panel. Then pirate all boards. It's the most economical method at this point.
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Old 07-05-2010, 02:26 PM   #9
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Default Re: LG 42PC3D-UE plasma: no picture.

Quote:
Originally Posted by el3ctroded
Here's what I would do: Look on ebay and other areas for an identical unit that turns on but has a broken panel. Then pirate all boards. It's the most economical method at this point.
Actually, that idea ALMOST causes me to retract my original evaluation.

The root problem is the OP is incapable of repairing the TV.

1. He doesn't recognize a power supply when he sees one. This is no shame for a doctor, a lawyer, an automobile mechanic, or hundreds of other professions. For someone wanting to repair a plasma TV, it's a show-stopper.

2. While there is a chance the two panels operate at the same voltages, it's a slim chance. So it becomes necessary to go through a full alignment. This requires a scope.

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Old 07-05-2010, 02:38 PM   #10
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Default Re: LG 42PC3D-UE plasma: no picture.

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Old 07-06-2010, 07:31 PM   #11
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Default Re: LG 42PC3D-UE plasma: no picture.

Go easy on these people. They will learn on their first couple of tvs and either decide to pack it in or learn and move forward. You don`t need a scope to get a picture. I have one and don`t always need it or use it. Ambition will always make up for lack of ability! We are all on a learning curve here....all of us!
I agree with the fact that some background in electronics would help alot. Plasma tvs can be a bit complicated for a beginner, but not impossible thanks to this forum!
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Old 07-06-2010, 08:26 PM   #12
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Default Re: LG 42PC3D-UE plasma: no picture.

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Go easy on these people. They will learn on their first couple of tvs and either decide to pack it in or learn and move forward. You don`t need a scope to get a picture. I have one and don`t always need it or use it. Ambition will always make up for lack of ability! We are all on a learning curve here....all of us!
I agree with the fact that some background in electronics would help alot. Plasma tvs can be a bit complicated for a beginner, but not impossible thanks to this forum!
For the most part that is true. If this were a bad Z-sus it could be replaced, the pot adjusted, and buttoned up by the OP in an afternoon using nothing more than a couple of screwdrivers (one insulated) and a DMM. The Y-sus is another matter. For that you need a 200 Mhz scope. The object is to do more than get a picture - you want to do the job properly so the set will continue to give a picture long after it has left the shop.

In some ways I am reminded of a cartoon I saw about 35 years ago in one of the electronics magazines. (For those who don't know their TV history, at that time the typical color TV had a couple of dozen vacuum tubes inside it). The couple are standing in front of their TV, looking at each other in dismay. Behind the TV is the TV serviceman who has just pulled the back off the set. He's looking at the set and saying "Golly!!! Look at all those bulbs and wires and stuff! What do I do first?"

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Old 07-06-2010, 08:41 PM   #13
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Default Re: LG 42PC3D-UE plasma: no picture.

You are right! This is a hobby for most. I am a mechanic with a degree in electronics. Nine out of ten mechanics are parts changers. I am not and I understand what your saying at this level.
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