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My tv keeps blinking on and off. How to fix? It's not the power supply

My Lg47lb5900 tv keeps blinking on and off. It's not the power supply. Any other suggestions? It's only 2 yrs okd

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Hi,

Presumably as you state that it is not the power supply, you have tested all the power supply rails or have tried a known working replacement power board?

There may be a problem with the LED backlight strips. As best as I can determine though the LED backlight power comes from the power board not a separate inverter board. It's probably too hard to tell if the display is still there when the backlighting turns off. Just a thought.

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@rburke26 what "keeps blinking on and off"? The power LED? The display itself? What did you check? How did you check?

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The display keeps flashing on and off. I ordered a new power supply and replaced it. Still flashing though.

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Jayeff the display is still there when it's flashing. It's very hard to see but I did catch it.

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... kind of sounds like you need a service manual. Before the days of replaceable circuit boards, that was the first step for repairing a television. Is there a burned smell? (you might have to get close to smell a burned component. Be sure power is not off, but disconnected) OR With unit on, you can always use a plastic probe to poke around on the printed circuit board. That could possibly reveal a cold solder joint. That has worked for me many times. If you do find a bad solder connection, and if it is not on a multi-layer board, it should be an easy fix. However multi-layer boards are common and can rarely (if ever) be repaired. New boards can be found online, but be sure it is [not close, but] an exact match. If something has gone wrong with a driver circuit allowing LEDs to get too much voltage, a new TV might be the only solution.

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@rburke26 if your screen does something in spite of the new power board which includes the backlight circuitry like this there will be an error with the LED backlight strips themselves. These are replaceable but it is not easy since you will have to dismantle the panel. Post your panel number, not the TV's model number so we can try to find the right strips for you. The numbers are usually on a label fixed to the panel.

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You said it is not the power supply. Does that mean you have taken the back off? Is the power supply built in or is it external, like a tablet 19 volt transformer? If you have opened the TV unit, can you identify a relay that clicks as it powers on? If so, as it powers on, hold a small rare earth magnet near the relay. BE CAREFUL not to touch anything, let the magnet stick to anything, hold it near any integrated circuit chips, etc. Sometimes the coil inside the relay gets weak. Holding a magnet NEAR the relay, (but not touching anything) can boost the magnetic field which operates the relay, allowing the contactor inside the relay to close (make connection) and the unit will remain on even after the magnet is taken away. If that works, the relay is bad.

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I ordered a new power supply board. It is basically a plug and play. Didn't fix it though. I have heard of the back light suggestion but have no idea if it's worth repairing.

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