When I turn on the tv there is a second of light and then it flashes to black. It turns on and there is sound but no picture. I have done light test and can see picture with the flashlight hitting the screen. I have replaced the Tcon board and the power board and no luck. What should I try now?
Hi Meleesa,
It is the backlight problem. Either the inverter has failed or the LEDs inside the panel have gone bad.
SOURCE: My tv is a lg
There's a good chance you have failing electrolytic capacitors either in the power section or the inverter section or both.
Any caps in these sections that look bulged at the top, or bulged/leaking at the bottom (look for discoloration of the circuit board around the base of the capacitor) need to be replaced.
If you repeatedly turn it off and on, eventually it'll probably stay on, but every time you turn it off, the unit will get harder and harder to start up until one day it just won't.
Sometimes you have to do the opposite to start it up and unplug it for some time and then try again.
If you aren't tech savvy, don't worry, read the rest of this solution and watch the videos.
If you are handy with a soldering iron and can identify the power supply and/or inverter / FM section for the backlights, an inexpensive handful of capacitors will likely fix you right up.
Match the capacitance on the capacitors. Go over voltage if you can, and still have them fit.
IE - it's not a bad idea to replace a 10V cap with a 16V or 25V or even a 50V, but don't replace a 680uF cap with a 500uF or a 1000uF (unless you are SURE it's only doing supply output ripple filtering,
and even then, you should go OVER, not under the uF rating).
Most of the caps that go are 10V 1000uF or 3300uF.
I found some great videos of the procedure (for many Samsungs with the same issue) on youtube.
http://www.youtube.com/watch?v=Mm51C_RDIZE
http://www.youtube.com/watch?v=BNHHrgX_6cs&feature=related
http://www.youtube.com/watch?v=8l0AUj8QUkg&NR=1&feature=fvwp
http://www.youtube.com/watch?v=Y7b_nTaZYcU&feature=related
As you can see, this issue spans plasma TVs, as well as large and small LCD TVs and monitors, amplifiers, computer power supplies and motherboards, and other electronic equipment.
The parts are cheap, and skill required is minimal.
A great parts source is Digi-Key, and you can order the parts online at www.digikey.com
They typically cost under a dollar a piece plus a flat shipping rate.
The parts usually arrive one business day later.
If you watch the third video, you will see that even someone with no soldering experience can perform these repairs as demonstrated by the woman in the video.
SOURCE: lg lcd can a bad tcon board kill all power
Yes , it can be a short on the board that will ask the SMPS unit to protect the power so as to switch off. So even with a multi-meter check you will be able to trace the short on the board, the drivers or any capacitor that is cutting off the power which must solve the issue.
SOURCE: LG 55LD520 picture problem
the problem with these sets (all brands) is it could be any board in the set or even the panel used for the display---
SOURCE: lg led tv backlight
Fault with its main board. Short circuited component/s at it. Contact any service technician; or the authorized service center. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. http://electronicshelponline.blogspot.com/ . In most cases, the main board might have to be replaced. If so, a software [firmware] update too might be necessary.
Fault to the main power supply regulator section. Either it will be a separate board, or the part of main board. Check and replace damaged component/s at its main power regulator [SMPS] section circuit. Contact any service technician. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts.
http://electronicshelponline.blogspot.com/
It will be best to replace the power supply regulator board as card basis rather than making "Surgery" to it; which usually will make loss for both money and time. Even though you can make it right, it will cost around an amount equal to the cost of a new board; including the cost of (spare parts + service charge) More to say, most of the spare parts to it will be difficult to get from open electronic spare part market. This is true to most of the flat panel TV power supply boards; irrespective of its brand and screen size.
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