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Apple IIe Power Supply Rebuild

Posted on September 2nd, by Shaun Merrigan in Tech, Vintage Computers. Comments Off on Apple IIe Power Supply Rebuild

The Apple IIe personal computer was manufactured from January 1983 through November 1993. I purchased an Apple IIe several years ago and put it into storage at the time. I recently pulled it out from storage and began the process of refurbishing it. Part of that process was rebuilding the power supply, which I will describe here.

The power supply appeared to be original to the computer with a date code of 47th week, 1985.

Apple II PCB Removed from case. Original capacitors in place. Build Date 47th week, 1985.

Examining the circuit board showed that the electrolytic capacitors were superior quality United Chemi-con.

Original Capacitors in place, output side.

By contrast, the line filter capacitor was a RIFA film capacitor of a type known to fail. Cracks were clearly visible in the outer case of the capacitor. It is theorized that these capacitors fail due to moisture ingress which causes insulation breakdown when voltage is applied.

Original RIFA Line to Line Capacitor, note extensive cracking in outer case.

All the old electrolytic and the line filter capacitor were replaced:

Original Capacitors Removed
Electrolytic Capacitors Replaced: Input side filter capacitors replaced.
Electrolytic Capacitors Replaced, Output side electrolytics. Dowsil 737 used as damping compound.

Where possible, I use capacitors with higher voltage and temperature rating than the originals.

All Electrolytic Capacitors Replaced, PCB in case.

After reassembling the power supply and reinstalling it in the case, I checked all the outputs. All were within specification.

Thanks for reading.

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