One of the screens turns on for a little bit but then turns to a black screen. I can still hear the sound good but the screen stays black. If I turn it off and then back on, it starts working again.
The other screen has never shown a picture. When i turn it one, i can barely see something show up but thats if I look really hard. what should I do?
I have repaired several n3750w viewsonics .. that may be similar to the 2750 .. in my case all the failures were caused by the same faulty part in the power supply .. the power supply has a 48 volt supply at about 7 amps .. the design uses a syncronous rectifier .. these are normally not used in supplies with that high a voltage out .. syncronous rectifiers make sense when the output voltage is low .. like 3 or 5 volts .. the parts are designed for that range .. but in this supply an IC is over stressed and fails frequently .. you might hear a chirping sound as the supply cycles thru an overload condition .. i modified the power supply to eliminate the syncronous rectifier and replaced it with a single shottky diode .. dissapation goes up slightly but reliability goes up a lot .. i have written an article on this. if anyone needs it i will try to find it . ..
The first one sounds like it has a bad inverter board. The second one could be a number of things, inverter board, power supply, lcd screen.
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Hi.
it sounds like you have an inverter change coming up in the one that starts and stops. the other could be trickier, but if you get one going, you could check each part of the dead one by the old try and true method.
while you have the back off. could I ask you to note what color of wire goes to which pin outs on CN2 and CN3
of the power supply? I have asked on this forum but I guess no-one has one open and I cant fix mine until I know what wires fit what pins on the PSU. the previous owner played around in there and cut all the terminals off.
TIA
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