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Old 11-28-2018, 04:49 AM   #109
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Join Date: May 2014
City & State: Tallinn
My Country: Estonia
I'm a: Knowledge Seeker
Posts: 4
Default Re: No Power Dell U2410 Monitor

Hi guys!
I have this DELL monitor at repair desk.
R853 (15Ohm) was dead and also GD6901. After replacing them both I got power, monitor responce to the buttons. But the problem is with PFC system, as it is pulsing. I get 330...380VDC (230VAC in power socket) on C854. I have checked feedback and over voltage circuits, all seems fine, but they are pulsing all together, as main voltage is not stable.
Checked with oscilloscope the outgoing PFC signal to the Gate of Q853 and saw, that the impulses are terminated and looks like this: I_I_I.........I_I_I.......I_I_I and so on...
As I understand, that some kind on the protection is applyed. But can`t figure out which.
VDD on SG6901 and L7575 is 17.64...17.66V.
If monitor is in sleep mode, voltage on C854 is 310VDC and VDD on L7575 is 17.7V.
Can anyone please help me? Any advice is needed.
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