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Old 10-03-2021, 12:51 AM   #17
Per Hansson
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Default Re: Dell 2209wa - momentarily blinks every two seconds [ Video + Audio + Service Manu

Originally Posted by ohren View Post
Anyway, the blown fuse resistor seems to have cut off the PFC MOSFET's drain, suggesting that... no PFC was happening? That would explain where all the heat came from I suppose (my understanding of AC is limited at best, but that's what I took away from reading about PFC). Am I getting close?

Well, this is more fun than gluing a heat sink to an IC like an idiot
I was going to suggest you to measure the voltage on the main bulk cap.
It should be around 400v when the PFC is working, or around 325v when it is not, so that would have been a tell-tale sign too.
Good job on locating the fault!
P.S: It would be a good idea to desloder the main bulk cap and measuring it on the component tester.
Just be sure to discharge it first because anything over 5v will kill the Atmega processor...
"The one who says it cannot be done should never interrupt the one who is doing it."

Last edited by Per Hansson; 10-03-2021 at 01:32 AM..
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