A friend approached me to rebuild his Apple II power supplies. One was a clone and one was an original. The original was already in pieces when I got to it, with components desoldered. The clone was very similar to the original Apple PSU, but cheaper and flimsier. Also one of the previous owners had "hacked" on it, adding an external fan and an additional power switch.
Deciding that I really didn't want to try and fix 40+ year old PSUs that were already in a state of disassembly, I decided the best course of action would be to replace them with something modern. The original owner liked this and agreed to my plan.
I've had a good experience using Mean Well PSUs so I ordered a pair of suitable units from Mouser, choosing the RPT60B based on its voltages and available amps.
These have one minor disadvantage, insomuch as the don't do -5v, but looking at the -12v rail, versus the rating the Apple II needed, I had plenty of overhead to use a 7905 to regulate some of the -12v rail up to -5v.
The switches on both units needed replacing so I had to widen the opening on the Apple II case ever so slightly.
I cut a sheet of acrylic sheet to act as an intermediatary layer between the original mounting posts and my new components. I used insulated crimps where possible and a screwdown terminal block to make construction easier.
Finally I ran up a small 7905 daughter board, complete with isolated heatsink to handle the -5v rail.
Nice! I wasn't even aware that such a small form factor replacement option exited for the Apple II PSU.
There are much nicer isolated white ceramic heatsinks for the 7905 that allow you to attach it to the grounded chassis. This is what I used when I replaced the original transformer PSU of my Pravetz 82 with a Mean Well RT-65B, which also doesn't have -5V:
Origianl.JPG
MEAN WELL RT-65B.JPG
That's pretty nice.
The ReActive Micro universal power supply option is quite small as well. And you don't have to buy the entire kit, if you're handy you can hack it together in a similar manner.
The kit:
https://www.reactivemicro.com/product/universal-psu-kit/
and just the power supply itself:
https://www.reactivemicro.com/product/universal-psu-63-watt-switching-power-supply/
I'd probably buy a lot more stuff in a finished state, like the nice stuff from RM, but as I'm in Australia, stuff from China or from a big supplier like Mouser is usually cheaper on shipping and much faster.
Chesh
Hi,
Thanks to CheshireNoir for sharing this.
CVT, do you still have the part number for the ceramic heatsink?
I don't have a part number (I usually just go to my local electronics store and get them), but you can find them on AliExpress. The one you want is the is the 12x18x1mm with a hole or the 17x22x1mm with a hole: https://www.aliexpress.com/item/1005004908844915.html
You also need the little plastic isolator washer for the bolt: https://www.aliexpress.com/item/1005001929208222.html
Many thanks, CVT !