throbscottle
Well-Known Member
I haven't proved this fault by replacing the cap yet, but I don't see at the moment what else it could be since it's connected direct to the output of a bridge rect. connected to the mains.
Anyway, the cap charges slowly, over a few seconds, to 81v, then suddenly discharges, then it starts to charge again, over and over. Such a strange thing, behaving as a relaxation oscillator all by itself. (I should find out what is going on and market it...)
This is the main smoothing cap in a cheap after-market laptop psu, pretty basic unit. Two of the bridge rectifier diodes had failed s/c, mains fuse had gone. I'd already replaced this cap a few months ago with a better one than the original (still a board pull though) since the old one had developed a high esr.
Has anyone seen this behaviour before?
Anyway, the cap charges slowly, over a few seconds, to 81v, then suddenly discharges, then it starts to charge again, over and over. Such a strange thing, behaving as a relaxation oscillator all by itself. (I should find out what is going on and market it...)
This is the main smoothing cap in a cheap after-market laptop psu, pretty basic unit. Two of the bridge rectifier diodes had failed s/c, mains fuse had gone. I'd already replaced this cap a few months ago with a better one than the original (still a board pull though) since the old one had developed a high esr.
Has anyone seen this behaviour before?