Electronics > Repair

hp monitor 1740

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kjn4685:
I have a hp monitor that goes off after a second or two. I've changed all the caps and diodes. Now I am changing the ccfls. I have tested all the voltages and anything that I can test. Does anybody have any ideas.
 s/n cnc63710j9.

hobo2566:
If your power bard looks like one in attached image, first check if transistors circled in red are OK (5706 or 5707 in most cases), if not check other components circled in green.

In most cases flickering on/off is caused by shorted transistor.

wraper:
Check secondary windings of the transformer(s), should have something around 1k resistance and less than 5% difference between them.

wraper:
If all capacitors are already exchanged and secondary windings are ok, 95% that one ccfl is dead and protection kicks in because of that.

Khaveer:
Is it only the backlight that turns itself off? I have a hp l1940t that had the same fault. I couldn't figure out what was causing the problem so I ended up disabling the overload protection hoping that without it the faulty part will simply release the magic smoke but it didn't. I've been using the monitor for a year and it's still ok. If I recall correctly I had to short a cap to disable the protection, so if you won't be able to find the fault I can take my monitor apart and check it.

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