Riddled TV Repair Forum

JP Lefebvre · Joined: 03 Jun 2008 Posts: 2 Location: Planet earth

Hello i bought this LCD tv about a year ago and i had experienced an intermitent problem with backlight panels.

Symptoms:

If you divide the screen in two panels with a vertical line in center, let say a left and a right panel. The right panel begin slowly to dim in brightness until it goes off, it can be followed by the left panel until off too.

OR All the screen goes OFF in a fraction of second.
When the screen is off the blue LED still ON. I have to push OFF/ON on the remote control to get picture back completly normal....
The problem can comes back in minutes only when it begins to do it.
If you put it to OFF half an hour it can take days before it come back.

Inside the TV there is two Ballast PCB with different connectors so you cant swap the Left and Right boards sadly.
Does it looks more like a Power Supply board problem?

Google

Jesse Mack · Joined: 22 May 2008 Posts: 600 Location: The Last Frontier

This unit uses two different sets (kits) of inverters (you are calling them ballasts, however they are actually inverters) Unfortunately these sets come at a high cost. They sell for $472.97 wholesale from the distributors. If you want to know the part numbers for the inverters I can supply but I need to know which type of LVDS cable you have. No, I do not think it is the power supply. There has been a problem with several different brands that cause multiple symptoms as far as backlight problems go. Carefully remove the shielding and tighten the mounting screws of the inverters and clean the shield on both sides with a fiberglass brush where the mounting screws go. Be very careful of the wiring that goes to the lamps as the lamps are VERY fragile. The problem has been poor ground returns for the inverters. If that fails, the only solution is to replace the inverters and they are expensive.

Hope this helps.

Jesse

JP Lefebvre · Joined: 03 Jun 2008 Posts: 2 Location: Planet earth

I was asking that question in hope that somebody knows exactly the cause of the problems at circuit level. My TV is on extended warranty and i changed the two inverters boards today with the service man. And what he told me is consistent with what you tell me Jesse.

When we changed the board i ask him if the replacement boards are exactly the same boards ( same as they will have the same problem in some time ) or they are upgraded version with this bug fixed. He told that he does not know. My fear is that the problem will be recurent but only time will tell.

Again thanks Jesse i will keep you inform if problem comes back. :wink:

Jesse Mack · Joined: 22 May 2008 Posts: 600 Location: The Last Frontier

Actually, there has been relatively a low failure rate on inverters. If they are going to fail they usually do so within the first year. I do not think I would be concerned if I had an extended policy unless it was about to expire.

Jesse