Sony Bravia FW-49XE8001 Intermittent backlight fault

Black screen, audio ok. Appears to be just the backlight that has a "loose connection" somewhere. When I press on the back of the unit the backlight came on.

I then open up the back of the unit and tapped different places in the back. And when I just lightly touched that white heatsink plate on the main board the backlights came on. I then loosened up all the screws on the Main Board and held it in the air and tried to wiggle on the cables but that did not seem to do the trick. But if I just so slightly bendt the main board or pressed the heatsink or twisted the heatsink just slightly the backlight came on.

Is it correct of me to assume there is an fault on the main board?

Is it waste of time to try to repair it?

I do not have the schematic for this monitor, nor do I have an oscilloscope. But I have a good multimeter EEVblog BM235 and I have been educated and practiced as a TV-repair man, but that is over 20 years ago and have never tried to repair any digital monitor or TV. But I understand the electronics inside there, even though I think it would be hard to find the exact fault without any schematic.

A quick search on ebay and I found a main board for the monitor, but it was over $75 + shipping and taxes.... not sure if it is worth it?

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Hi

Sounds more like a dry solder joint. Check all the joints around the area where you were pressing to make it work. Use a magnifying glass and a strong light. You'll probably have to remove the board to view the connections, unless it is a SMD type of board

da

It is a SMD type of board with a lot of layers... I have already tried to inspect it visually on both sides but the tracks is so thin and very hard to see. May need a magnifying glass to inspect it closer.

But in the meantime I have found a temporary solution (a very "MacGyver" solution I have to add); took a spring from a ballpoint pen and stretched it a little, cut a inch of the rear part of the ink-tubing of the pen and put it inside the spring. Taped this construction so one end of the spring touched the heatsink and the other touched the plastic back cover. Now the backlight stays on! I know this is not going to last, so I'm still looking for a permanent solution.

I also have to add that the monitor has only 4-5 hours of use and is new. It was replaced under warranty and Sony said they did not wanted the defective monitor back since it would cost more to send it then the value of the unit (we live far north in Norway). I hoped I could repair it myself...

da

F0NIX post some good pictures of your boards, the heatsink etc. with your question. That way we can see what you see. Use this guide Aggiungere immagini ad una domanda for that.

da

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