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aoc monitor prob

Y

yhan

Jan 1, 1970
0
greetings!!!

i am repairing a 14" AOC monitor, model: 5en, black chassis. Its first
symptoms was a ticking sound with no other action. I found a shorted
MOSFET transistor (IRF634B) in the secondary side of the low voltage
PSU. Tested other components in the PSU but they are ok. After
replacing the transistor, it now turns on but the display becomes too
big and it comes on and off accompanied by a clicking sound. I observed
that its the high voltage that comes on and off. Then after that cycle,
there's no raster anymore. But the frontpanel light is on and the
control for screen adjustments responds when pressed. Can anyone give
me suggestions on how to fix the problem? thanks in advance.

regards,

ian b
 
Y

yhan

Jan 1, 1970
0
an additional info to my previous post: after replacing the transistor.
it stopped ticking. i measured the main B+ when not connected to video
card. its only +90v. i think it should be 200. now, i noticed that when
i connect the video cable to the video card, it attempts to display the
information but resulted to whining on/off and blinking of power led
(green color).Then i noticed the high voltage come & go. i measured the
voltage during this phase. it rises and falls back to 90v.
what am i missing?

thanks in advance,

ian
 
Y

yhan

Jan 1, 1970
0
i should say it happens whenever it receives signal from the video card.
 
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