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Rick williams
Rick williams, Technician
Category: TV
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Hi, my LG 42PT85 plasma is taking a while to power up in the

Customer Question

Hi, my LG 42PT85 plasma is taking a while to power up in the morning, it is the same if I power up by remote or power switch. When I switch on the red standby light turns green then goes out. You have to continue to press the power switch/remote for 10 minutes then you hear a whirl, sounds like a hardrive starting up, but it still does not come on. If you continue for about another 5 minutes it will eventually spark and come on. Once it is on it will be fine for the rest of the day. If it is left for a few days without being powered on the process will take longer to get it to power up.

Any ideas ?

Kind regards,

Submitted: 8 years ago.
Category: TV
Expert:  Rick williams replied 8 years ago.

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,

(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 POWER SUPPLY, 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 8 years ago.
Hi Rick, thanks for the reply. Been busy at work so have only been able to review the problem again tonight. I opened the tv and cleaned out all the dust. Tried to switch on but still same problem. When you press the remote the standby light goes from red to flash green then the set makes a click and the led goes out, then comes on red again. Checked the capacitors near the top of the set and one of them seems to gave a slight brown gunge seeping from the top? Again tried turning on for about 10 minutes then the set make a whirling noise as if it was going to start up, then clicked off again. It continued to do this for another 5 minutes then eventually started up. I have made a couple of short videos of the process, with the back off the set, so if you want could upload to YouTube and give you access. I am not experienced enough to change individual capacitors, ok if it is a part to be replaced but was wondering what kind of cost I would be looking at to repair, or replace a part. I look forward to your reply. Kind regards,Callum.
Expert:  Rick williams replied 8 years ago.
You may can get away with taking it to a local shop,, Just the board and they may charge a small fee for changing the caps,, if you let then know that they are not responsible for it working or not,, And to answer your question when its this simple i would say they may charge 1-200.00 not sure,, But i would,, You dont have to upload anything friend you have found the problem already,, now up to you to get the caps changed or board itself good luck,,