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Thread: Making a C64 power supply?

  1. #1

    Default Making a C64 power supply?

    So I currently just scored a working first gen c64 with box and cover for $45. It does not include the power supply and the power supply would cost more than the entire machine. So I did some research and found the pin-outs/schematics.

    I currently have a 9vac 780mA power supply which I could remove the transformer. I also have tons of DC power supplies 5v,12,9. and tons of components. So from what I can understand. The 9vac inputs are connection so It does not matter which one I use. Or do I splice the 9vac rail into 2 wires for each pin? then connect all ground wires together then connect that to the ground pin on the c64? Also is pin 4 just not used? Just for cable plug stability. Correct me if i'm wrong, So my question is, Would this work? Also any advice would be appreciated. Also here is the ebay listing I purchased it from: I hope is shows for you:

  2. #2
    Join Date
    Jan 2012


    That schematic of the power supply seems to show also some parts that are already inside the C64 board. If I recall, there is only the 5 volt regulator (of course the rectifier diodes and capacitors and transformer) that are inside the main power supply unit.

    I would suggest that you google some more for a C64 P/S schematic if you are going to build one. There will be some suggestions that you are better off to buy but that they would be more $$ than the cost of your C64.
    Here are some that were discussed in some forums:
    1. Building or assembling your own:
    - None has recommended to stick with the old one due to dangers of blowing your C64 (being old when the VR will short)
    - Get a 9V ac transformer and connect that to the 9vac, then get a quality 5V switching (at least 2A) power supply (connect this to the 5V dc rails) and have a common AC switch to power these at the same time
    - try to get a working C128 (change the capacitors with a new one) , replace the cable with a corresponding C64 plug (connector)

    2. Buy a P/S from Ray Carlsen...and some says you are set for another life of the C64.
    3. Then buy a SAV64

    The last 2 suggestions will cost you a lot of money for sure!!! but they are the best!!!

    Aside from this forum, you will see a lot of discussions on P/S that made you think why C64 ?????


  3. #3


    If you have the 9VAC transformer, then it's pretty easy to just hook up a set of rectifier-diodes and a regulator for the 5VDC. The original has a mere 7805, but as mentioned a simple DC-DC buck-converter will be way better. The major reason the old PSUs fail is because the parts inside are run outside their specs, and the fact that they filled the things with Epoxy (= no ventilation).
    Current systems owned by me:
    Vintage:IBM PC/XT submodel 087 ( 1983 ), [Kon]tiki-100 rev. C (1983), Compaq Portable I ( 1984 ), IBM PC/XT submodel 078 ( 1985 ), IBM PC/XT286 ( ~1986 ), 3x Nintendo Entertainement Systems ( 1987 ).
    Obsolete:Commodore A500 ( ~1990 ), IBM PS/2 model 70/386 type 8570-161 ( 1991 ), Atari Lynx II ( ~1992 ), Generic Intel 486SX PC ( ~1993 ), AT/T Globalyst Pentium w/FDIV bug MB ( 1994 ), Compaq 486DX4 laptop ( ~1995 ).

  4. #4


    Quote Originally Posted by RizThomas View Post
    2. Buy a P/S from Ray Carlsen...and some says you are set for another life of the C64.
    3. Then buy a SAV64
    Or you can buy Ray Carlsen's own Computer Saver. See
    The last 2 suggestions will cost you a lot of money for sure!!!
    Well, Ray Carlsen's "bare bones" North American power supply is $35 US - see

    His Computer Saver is $20 US for the internal version (if you good at attaching it by soldering).

    Last night in Sydney,
    Robert Bernardo
    Fresno Commodore User Group

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