astmario
1 Copper

RE: U2412M, Repair a defective diode

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Hi,

I opened my monitor that had same problem, found out that LD7750RGR circuit is dead and also named UF5404 diode. I was full of joy for finding problem, but closer inspection showed that 2 SMD resistors around LD IC are burnt out and I cant read their values.

If anyone can post R611 and R612 resistor values I would be very grateful!

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jeremywoodham
1 Copper

RE: U2412M, Repair a defective diode

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Hello astmario.

If your eyes are anything like mine I have to de-solder and look at it under a magnifying glass to get values.

If I do open up my monitor again  I will try to find those values.

Cheers

J

jeremywoodham
1 Copper

RE: U2412M, Repair a defective diode

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www.eevblog.com/.../

Maybe that will help?

astmario
1 Copper

RE: U2412M, Repair a defective diode

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Thank you for reply!

My eyes are not much better but those values can be without desoldering just by using magnifying glass or by list taking picture of them and zooming on screen Smiley Wink I gave a look to topic you linked but I don't like that post thay says that you can just use safely 10R just like that, those resistor in my knowledge regulate voltage so using wrong one can have great impact on on output voltage so can damage something on processor board. And I looked that damaged board picture and one resistor it totally missing, another one is blurry lol Smiley Happy

So far I changed LD7750RGR circuit, 2SK4108 FET  and UF5404 diode and today I will recap the board with new capacitors to ensure I don't need to repair it for a longer time, I just don't trust those Elite caps. Everything else is double checked, so recap and finding R611 and R612 values is only thing left to do!

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astmario
1 Copper

RE: U2412M, Repair a defective diode

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I found a working monitor of same version in my office, so I was able to open it and read values, so I will post it here for anyone else with same problem. A friend of mine with good camera took a picture, so here it is.

Also to mention burned resistor R615 on another side of the board, but it is normal and can be read easy.

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SatWgat
1 Copper

Re: U2412M, Repair a defective diode

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I'd like to express a HUGE thanks to cryptos10 (and others who contributed) for this info. I replaced a pair of (what looked like burned) UF5404 with new ones and it worked!

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