Samsung 760V TFT LCD monitor goes black on turn-on

[biddy67]

Common problem with these apparently, you have to turn it off and on over and over to get the screen to properly light up which it eventually does, otherwise turns black in a few seconds. If it is the inverter, which inverter board do I get, and is it possible to repair the inverter board? When troubleshooting, what should I do, what measurements to take?

For those with same problem, what I do is just have no screensaver and leave monitor on all the time, that way it is always working.

[biddy67]

I found this:

http://ezinearticles.com/?Repairing-Samsung-153V-LCD-Monitor-With-Dim-Display-Problem&id=548677

Looks like leaking capacitor problem. Given monitor still works on warm up and after turning off and on many times, cap replacement should solve right? No need to replace the board altogether at this point? I still have not looked under the hood, good idea to stop using before things get worse...

[biddy67]

This unit was experiencing the common symptom of screen going black
after a few seconds of turn on. Turn off and on again, problem would
repeat, but things got better with some dark splotches on successive
cycles of turning off and on until after about 2 minutes, the screen
would stay on properly and then work fine thereafter.

I disassembled the unit and on the power board I found possible
sources of the problem. There was a film capacitor (C11) pushed up
against and in contact with the heat sink on a transistor (only heat
sink on the board). It was brown in color, but on further inspection,
the original color was bright red, the brown discoloration may have
been due to heat or leak through. Additionally, the power mosfet
MTP23 was leaking a brown substance from the lead end onto the board.
All the electrolytics tested fine with my esr meter and also looked
fine.


The "Display Type" is GH17MS with a "Model Code" GH17VSSN. The power
board was designated GH15/17 Rev 3.0. The value of C11 is
unreadable. How would I got about finding the value of this capacitor?

OK, I found a board that appears to be identical to mine here:

http://www.lcdrepair.us/1504fp-power.html


The bad mosfet is in the upper part of the board just to the right of
the bank of six capacitors, you can make out a corner of it behind the
white ribbon cable. The mysterious capacitor C11 cannot be seen, it
is adjacent to the heat sink on the same side of the mosfet. There is
another similar film cap, but it is too far from the heatsink to make
contact with it.

[biddy67]

Replaced the cap and mosfet, all is well.