LC PSU Board inside an Apple IIe PSU (Power Supply) — #5

Post #5 by techknight

Source Forum	68kMLA
Category	Hardware
Post Date	Tue, 26 Mar 2013 - 03:06
Original URL	https://68kmla.org/bb/threads/lc-psu-board-inside-an-apple-iie-psu-power-supply.27625/

Post

I could not get the switching transistor to fire.
I tried everything.

The only thing i can think of is the Step down Transformer is bad some how.

I even changed the the switching transistor, and the caps that give it a Kick start.

Started racking up the hours on it and said the heck with it...

and those god dam HV Caps do not have a discharge resistor, so I had to keep discharging them by hand.

pain in the butt.

Works now.

Charles

I doubt the transformer is bad. Possible, but i doubt it. Did you check the film caps? ive seen those fail and cause that exact thing. Also you check the soft-start resistor? because a feedback oscillated flyback power supply requires a few things to be right before it will oscillate.