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Rick williams
Rick williams, Technician
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I have an LG plasma TV model 42PG20-UA. The blue(power) light

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I have an LG plasma TV model 42PG20-UA. The blue(power) light comes on, but nothing else happens; no video, no sound. What might be the problem?

Hello friend, Thank you for posting your question on Just Answer! I will be happy to help you with this problem, And possibly help you save on these Labor charges today, So please don't Accept my answer unless you are satisfied, Can you please give us some more information so I can better answer your question?


have you any Television electronics experience? if not A family/friend with electronics skills that can help you out.

Do you have a meter and Tools?

Are to trying to repair your Self?

Just know what to say to the tech, so time isn't a problem in repairs?


Customer: replied 6 years ago.
I am a high school electronics teacher. I also built and sold computers for several years. I was, however, never very good at working on analog CRT's. I have a digital multimeter and an o-scope if necessary. This TV looks very simple inside; only about five boards, and looks like no adjustments should be required. Just identify the bad board(s) and repalce it (them). I hope I'm right. I'd like to do this myself.


(Please click on high lighted words) this is my sample may not be the same model but doesn't matter the technology is the same.



Would like for you to take your meter and place it on DC voltage the positive end on every connector that says a voltage and the negative wire to the panel this is the best ground. Turn on and see if the voltage is present at the VS, VA, V-scan, According to the Label. Also if a voltage is missing remove each board from the power supply to make sure they are not holding down the voltage If you don't find one that's trying to climb, or shows close to what it should be, another method is to locate a short circuit place meter on ohms or beep test follow same procedure no voltage should be shorted to ground. And this is the problem. You can unplug each board one at a time, Starting with the Y-SUS then the Z-SUS.

Friend this is a very common problem with plasma. Within the power supply the capacitors

Start to fail and the way you can tell is to check them visually for swelling or expanding of the top.

It will be easy to see the bad caps will not be as flat on the top as the good ones


Normally the parts for this unit is a kit Y-SUSTAIN AND Z-SUSTAIN BOARD, this is what most manufacturers would want you to do, purchase them. But go to high lighted words and go through all the voltage checks to find the bad part, here is also a chart that should help a lot, also this is a picture that will help with identity.

Well Good luck friend, and if my efforts are appreciated, feedback and a bonus will be appreciated


Thanks Simplified click here

Customer: replied 6 years ago.
Thanks Rick! I'll have to wait until tomorrow to do the work you suggested. Can we continue this tomorrow evening? Also, I have taken pictures of the circuit boards. Can I send them to you? How can I do so? I'd like for you to see my TV and help me identify the Y-sus and Z-sus boards. I visually checked all the caps and didn't see any obviously bad ones.
Sure,, upload on your tool bar,, using the tree picture
Customer: replied 6 years ago.

Here's the whole thing. I also have pics of individual boards. How can we pause our discussion until tomorrow so I can check the voltages you suggested?
just reply to this message later
Customer: replied 6 years ago.
ok, Rick. I've marked this page. I hope I can get back to you tomorrow. Your help is certainly aappreciated. I don't want to stiff you on the money thing. If I can get this thing to work, it'll be worth more than $13. If you don't hear from me its because I can't figure out how. My email address [email protected] If you don't hear from me tomorrow, email me, please.
This message dont reply until ready
Customer: replied 6 years ago.
Results of this evenings work:
I set out to check the voltages that you suggested: VS, VA, etc. However, I could not get the unit to power on. Although the blue LED surrounding the on/off switch is lit, pushing the putton produces nothing. There were no voltages at any of the points you mentioned.

The power button leads to a board that contains all other inputs and outputs. I think its called the main board. I decided to unplug the connector at the power supply board that leads to this main board and see if the main board is getting power. When I did this, and plugged the unit in, it tried to power up. A relay clicked and an LED lit up on one of the other boards. I didn't leave it on long, only about 15 seconds, not long enough to check voltages anywhere else. Could this main board be the problem? I didn't expect the TV to power up with this board disconnected.

Yes, sir sounds good to me,, main board


These are some part stores, CALL THEM IF POSSIBLE always check with manufacturer, and you may need the name of the part and its part number off the part itself

And this one rebuilds board's very helpful company


Well Good luck friend, and if my efforts on trying to help you save on those large labor charges are appreciated, feedback and a bonus will be appreciated







And also manuals sites


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