C64 Power Supplies

If you want the short version of this page:

Purchase a modern power supply for your C64 and do not use an original Commodore power supply. 

You will likely see online merchants selling the C64 including the original power supply. The original power supply may make a nice addition to the collectability of the purchase, but I strongly suggest you never plug it into the C64 even if it tests for appropriate voltage. If you really like the look of the original power supply on the desk with your original C64 just put it on the desk and look at it...but don't use it...ok? If you are handy with electronics, there are some modification designs on the internet for using the original C64 power supply case and converting the internal to safer modern power supplies. 

The C64 receives voltage from the external power supply using both a 5v DC signal and a 9v AC signal. The 9vAC signal is then converted to both 5vDC and 12vDC to power the VIC and SID chips as well as 9vAC to the user ports and the 5v DC is distributed to the other chips.

All this was designed to reduce interference from the audio and video sections of the board. The 5vDC section of the board has a very narrow range of operation. Too low (like 4.6 volts) and it doesn't work and too high (like around 5.4v) it may ruin the chips on the 5v section. The original C64 power supply is known to fail on the 5vDC signal at any time without warning and it may fail high destroying the board. 

The good news: There are some relatively inexpensive modern options available to substitute. And if you must (just don't) use the original power supply, at least use a power saver to shut down if the voltage goes high. 

My recommendation is to use a modern C64 power supply. My top preference is Ray Carlsen's custom power supplies. 

One additional benefit of Ray's power supplies is you can ask him to add floppy drive power or other Commodore machines like the C128 or Amiga if you need it. Ray is a legend amongst the C64 community and has many resources on his site including his power supplies. He is also very responsive to email, has fast shipping, and is very helpful. 

Other options include Keelog and Electroware. There may be other good options, but these are the ones I have used. 

I try to keep a few modern power supplies on hand for additional purchase or bundled with my products. I really don't like the idea of spending time restoring these great machines just to have them destroyed by the wrong power supply. 

 

Disclaimer: For informational purposes only.  Flashback Fix does not formally endorse or warrant any products referenced and has no financial or marketing interest with them.