Electronics > Repair

Another LCD monitor repair

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f:
Hello all, I have an older 2006ish LCD tv that I got for free. It does not turn on, I have traced the problem to the logic board.
I have no idea where to start on this thing. The only thing I can get it to do is if I unplug and plug back in the power plug from the supply to the logic board, the power led will come on for half a second and go off. I have looked for cold solder joints, but they all look good. I have tested the board using two different power supplies, so I know its the problem.

Anyone know a good place to start? Here's two pics of the board itself.

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Tv model: Samsung 940mw s

Alana:
I'd try to remove and replug that rom chip in plcc socket and reflow those two main ICs. It helped with my samsung of the same era but only for a while - if i remember correctly those logic boards are prone to falitures.

Crazy Ape:
There's plenty of colour adjustments in the service menu.

Grab this: Schematics, service menu info, etc.
http://linfotech.co.uk/schematics/Samsung/Samsung%20%20940MW_940MG.pdf

Edit: Ignore colour adjustment comment, I was getting two threads mixing up. This is your board and schematics though.

f:

--- Quote from: Alana on October 30, 2013, 04:56:56 am ---I'd try to remove and replug that rom chip in plcc socket and reflow those two main ICs. It helped with my samsung of the same era but only for a while - if i remember correctly those logic boards are prone to falitures.

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I tried reseating the rom, but I have no way of reflowing. By main ic's do you mean the big square ones?




--- Quote from: Crazy Ape on October 30, 2013, 05:03:15 am ---There's plenty of colour adjustments in the service menu.

Grab this: Schematics, service menu info, etc.
http://linfotech.co.uk/schematics/Samsung/Samsung%20%20940MW_940MG.pdf

Edit: Ignore colour adjustment comment, I was getting two threads mixing up. This is your board and schematics though.

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Thank you, this will probably help.

Stonent:
I've fixed HP printers by baking the motherboard to reflow it. You take the board and put it in an oven, elevated above the pan using balls of foil on the corner of the board and bake at 350 for about 8 minutes then carefully remove it and let it cool for 30 minutes till an hour. If there's a brittle solder joint that can frequently fix it.

http://www.fixyourownprinter.com/forums/laser/48992#88

Also on monitors, popped capacitors in the PSU, a fried MOSFET or a bad power button are common.

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