Simple DIY Commodore C64 power supply solution.

06/09/2016: Please read this page in its entirety if you are considering making this adapter. Please understand the difference between AC and DC. Also note that the adapter I am describing is specifically for 'wall warts'. That is, power packs that are intended to use as is and are NOT to be pulled apart or modified in any way. This adapter is made so you don't need to play with mains power. Also note that I show some photos of how I modified an original power supply. This is purely for interests sake and I neither describe or recommend pulling apart an original power supply. Opening up an original power supply clearly exposes you to mains power and the hazards that entails.

10/08/2015: Important! Below I have touched on the fact you should not get a 2 dollar USB supply. I may not have stressed (or indeed even understood myself) how important that is. This article is an eye opener! And how about mine? Still going after a year I'm happy to say!

23/08/2014: One day I noticed out of the corner of my eye a familiar beige object on the side of the road. It was a C64C. Naturally I rescued that bad boy! Most fortuitous as for the last year or so I had been thinking of teaching myself BASIC on an 8 bit machine. The choices in my mind were Apple IIe (which we used in high school), the ZX Spectrum (which I played around with at my uncles place in Holland) and the Commodore 64, which I can't recall ever having used, but for which there are a butt load of resources available.

A butt load of resources- except of course the power supplies! From what I've been reading, it seems Commodore wins the prize for crappiest designed PSU. Apparently not only did they get really hot, but because of that they would fail. And fail in a most mean-spirited way. The voltage regulator often would let the voltage climb until it toasted your computer! And it seems most are a pain to repair because the regulator is embedded in resin.

Anyway, having tested my C64 on a friends C64 PS and finding it works, I thought I'd just get a new aftermarket power supply from ebay. Nothing. Most surprising since not long ago I had bought an aftermarket supply for my Atari 2600. The rub is that the C64 has two voltages going in to it, and both AC and DC! You are here because you already know this and are as confused as I was after learning TOO much from all the forums. But you still need an alternate. So I'll cut to the chase.

All you need for your C64 to work is a good 5 volt DC supply and a good 9 volt AC supply. Furthermore, you need at least 1.5 amps (1.7 for the C64C) on the 5V side, and at least 1 amp for the 9V side. If like me you have scoured the forums and found a whole bunch of conflicting information, you would have come away almost none the wiser for your journey. The information is out there, just buried. So here is everything you need to know to get your Commodore going again in one handy web page.

KNOW THIS: Many, many very complicated devices nowadays run on 5VDC, via USB. This is the first part of the puzzle solved. If you can safely run your 500 dollar phone on it, chances are it will be fine for your C64. Get a 2 amp USB 'wall wart' and half your troubles are over. (Note: Any quality 5VDC wallwart will do, whether it's made for charging via USB or just an all-round power supply).

KNOW THIS ALSO: PAL region Super Nintendo consoles use 9VAC! The power supply is rated for 1.3 amps furthermore. But it must be an original one. Many of the aftermarket power supplies actually output DC as it doesn't matter on the PAL SNES.

With luck you will have one or both of these power supplies already, saving you money. Then you just need to make an adapter to connect these two supplies to your C64.

 THAT IS ALL YOU NEED TO KNOW!: From a technical perspective anyway. Too many people are getting hung up on technical details. Forget about ATX this, and voltage regulator that. I bet all you want is to run your C64, at least as safely as before (and actually safer). As well, I am taking one for the team in a way. You have the date I first did this, and I will update this page from time to time (see bottom of page for updates) so you will know if this adapter still works.

The other confusing thing is C64 DIN pinout diagrams. There seem to be a few variations on the net, yet there can only be one way! Or so I thought. Once I thought about it more, I realised that the main variation was mirror imaging.  Once you've studied a few you realise  that straight up, pins 6 and 7 are interchangable since they are AC and that you can't possibly get pin 2 wrong as it is unique. 4 and 5 were my sticking points. Not only are there diagrams out there basically showing them on different sides (!) but staring at these diagrams makes me dislexic- am I looking at the 'solder' side, or the 'pin' side? It turns out though that if 4 and 5 are reversed, the computer will either power up, or not. If it doesn't, assuming there isn't something wrong with your machine, you just reverse 4 and 5. So if all you screw up is swapping 4 with 5, nothing should go wrong. In summary, pins 6 and 7 are the 9VAC, pin 2 is -5VDC and you can have a guess on pin 4 or 5 for the +5VDC without risking blowing up your C64!

Below is the C64 power pinout diagram I ran with and which worked for me. I used pins 2, 5, 6 and 7. It is very clear that you are looking directly at the female end as it appears on the case of your C64 (you can thank teutonic efficiency for that!).

C64 pinout

Here is a picture of the adapter I made to replace the missing power supply, which like I say, allows you to run your Commodore using a 5V USB supply and a 9VAC SNES supply. Also a pic of my C64C after I crossed my fingers and switched it on. Last are the two supplies. You could put them into a jiffy box for neatness, or if you have a dead supply put them inside that (if they fit). Then you don't even need to buy any extra plugs, just hack the original cable (",)

So far my C64 has been running for about an hour, I can see the lovely blue glow on the keyboard out of the corner of my eye (update, ran it for maybe 8 hours with no probs, and also a couple of hours with a game loaded up with a title screen and SID tune going). Nothing seems to be getting hot- my adapter or supplies. So if I were to put the supplies in some kind of jiffy, I think it would need just a small hole top and bottom, at most for cooling. Of course I imagine if it were running an intensive program it would be drawing more current, but I think everything is going to be ok. Like I say, I'll update from time to time

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5 volt line: 2 AMP USB wall adapter. DO NOT GET A 2 BUCK KNOCKOFF!

9 volt line: SNES power supply (PAL. input:220-240VAC, output:9VAC)
NES power supply (NTSC. input:110VAC, output:9VAC)
The original C64 supply if you have one. After all, it's usually the 5VDC side that is the problem. The 9VAC side should still be fine and will be as safe as any other 9VAC supply.

Inline male DC power connector (2.5 x 5.5 for PAL SNES. 7 or 8 pin DIN socket if using original power supply)

7 pin DIN plug

An old USB cable to hack, heaviest you can find

Note 1: If you are doing a hack like this, you probably know your way around a multi-meter. If you are not sure which wires on the USB cable are the 5V lines (and this is something you definitely don't want to be taking a guess with!), to test you need to put a light load on them. The easiest way is to get a resistor and wrap the legs around your multi-meter probes. You don't want to draw much current, I found a 220 ohm resistor and used that. To be safe I think it prudent not to go below say 50 ohms. Careful not to short anything!

Note 2: there seem to be more SNES supplies than SNES's nowadays so it's a cheap option for all of us in PAL land (not often 'PAL' gets a win!). With luck, like me you'll have one or both supplies already. If you are in NTSC land, you will need to get an original NES power supply or a generic 9VAC wall wart, for it seems that the NTSC SNES power packs output 9VDC (just check yours to see, I'm happy to be wrong about that!).



I have read here and there that if you have two supplies, it might not be a good idea to use the power switch on your C64. I haven't had any problems, but since I don't want to wear out the switch anyway, I've set up the system so that a small extension lead has a double adapter. One end goes to a cheap powerstrip with an on/off switch, where I plug in the power supplies and the other end goes to the monitor. Now I switch off my C64 via the powerstrip switch, which doesn't effect the monitor and makes me feel a bit safer (",)


Turns out the HP Touchpad charger does indeed fit inside the wedge PSU!Some pics:

1 2 3 4


Finally made my I/O through box doohicky so I can measure the voltage of different supplies connected to the C64. Here are the results:

Cygnett USB (the one I've been using all this time): 4.9V

HP Touchpad charger: 5.04V

Original 'wedge' PSU: 5.16V

While 4.9V should be good for helping to keep the chips run just that bit cooler, the HP is a top notch device so I may use it from now on. I may use it to replace the 5V line in the wedge. It's compact enough that I think it will fit inside the housing.


Well, it's been a little while but the commie is still going well. Had a bit of a heart attack when the screen started dimming and flairing sporadically. Then realised it was actually the TV! Phew! I have also bought myself an SD2IEC from Poland. The seller on ebay is 'c64fanatic'. Excellent product, and including post, was about half the price of competitors! If you haven't heard of this device, check it out. An SD2IEC can't run everything (for that you need something like the 1541 Ultimate II), but it does do a hell of a lot. The latest firmware update allows Maniac Mansion to load, which is great because I've been meaning to check that game out for years.


Still going well! I am going to make a little I/O box so that I can easily connect a voltmeter to my machine. Then I can connect different supplies to it and see what the different voltages are. I am doing this because I bought a HP touchpad charger, which is supposed to be about the best of the USB chargers out there. But then I realised it is rated at 5.3V. This is apparently at the upper limit of what the C64 can handle. But there should be a bit of voltage drop so I aim to find out! I am hoping to have a supply of about 4.9V at the computer.


I received an email from Eric:

"I found your site http://dannygalaga.com/c64.html via Google and while your info is quite useful, PAL SNES power supply isn't common on this side of the ocean, and USA power supply are DC output. Getting imported PAL power supply won't do well because most houses don't have conventional 220v outlet.  I can't see people setting up their C64 next to a dryer with some kludged up plug adapters simply because 220v outlet aren't found elsewhere more convenient or with European style plugs.  Plus I have no idea if PAL SNES power supply would work right with 60Hz power.

However NES is quite common, its power supply is 9v ac 1 amp and it's fairly common around here. So for USA and Canada C64 users, they could consider using NES power supply insteal of PAL SNES supply. Only the original one will work, many of the 3rd party replacement outputs DC only and C64 needs that 60Hz (or 50Hz for PAL) to run properly"

So there you go! I will update the page accordingly (",)


Still running well. I haven't been using it much because finding the C64 was sort of 'before it's time'. That is, I had other projects in the pipeline before I found it. When things have settled down in my other pursuits, learning some programming on it is definitely on the agenda (",)


Still going strong. I have been made aware that using a cheap and nasty USB supply might not be wise. So if you are using a USB supply, spend more than 2 bucks! Mine is a CYGNETT, cost about $20 from a shop. A quick look on ebay tells me they aren't much cheaper online!


I made my own joystick, after I had a 'moment' with my Gemstik while playing Elite. The Universal DB9


Well, it's been about a month since I did this and everything seems to be running smoothly. I have sometimes played Elite for ten hours straight.


Found an old Netgear psu today in my box of tricks: 5V, 2A. Might rewire my adapter to use that later on. For now I'll keep using the USB supply so that I can  keep the updates relevant to that


I have since worked out how to load programs onto the C64 using an mp3 cassette adapter hooked up to my mobile phone and datasette (update coming on the how to). This has given me the opportunity to run Wizball on it, the title screen is an excellent workout for the SID chip, and thus the SNES supply. Have run it for several hours this way.


I received an original supply, and wouldn't you know it, the +5V is on 4 instead of 5! I thought I should put my money where my mouth is and see what would happen. Powered up just the same! It would seem then that on the C64C at least, both 4 AND 5 are wired in the machine for +5V. I don't know about the earlier models though, but I get the feeling 5 is more likely than 4 so try that first. I also tested the voltages while I was at it: 9.9VAC and 5.26VDC.

All things C64 here

An excellent writeup on this forum about rejuvenating a C64

So you've set up a double wall wart ps yourself. Why not list your specs here?
lemon64.com/wallwart/USB charger specs

something exciting coming soon for the 8 bit world

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