Commodore 64 power supplies including Part No. 902503-06, Part No. 902503-11, Part No. 251053-11, Ray Carlsen PSU and Ray Carlsen Computer Saver

C64 Power Supplies

Commodore produced a fair amount of different looking power supply units (PSU) for the Commodore 64 home computer. I have collected some of the most common versions from the European market in this post to show some of the differences between them. All brown/greyish PSUs were made for the Breadbox and can supply 1.0A @ 9V AC and 1.5A @ 5V DC, while the white PSUs for the Commodore64C and C64 Games System provides 1.0A @ 9V AC and 1.7A @ 5V DC. At the bottom of the post is a more modern C64 PSU made by Ray Carlsen with a build-in computer saver (more on that later).

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Commodore 64 PSU #1 (Part No. 902503-06)

This particular PSU uses a T160mA fuse. It has no power switch on the rear side. The fuse plate is rectangular shaped.

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Commodore 64 PSU #2 (Part No. 902503-06)

This particular PSU uses a T160mA fuse. It has no power switch on the rear side. The fuse plate is square shaped.

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Commodore 64 PSU #1 (Part No. 902503-11)

This particular PSU uses a T200mA fuse and a T1000mA fuse. It has a power switch on the rear side. I like having the option of turning the PSU off whenever I do a repair job to make sure no power is still flowing into the electronics when I remove IC’s for testing/repairing. The fuse plate is rectangular shaped.

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Commodore 64 PSU #1 (Part No. 251053-11)

This particular PSU uses a T1600mA fuse and a T2500mA fuse. The fuses are placed on the inside of the power supply. This particular PSU is repairable.

part. no 251053-11 commodore 64 power supply

Part. no 251053-11 commodore 64 power supply - reparable

Part. no 251053-11 commodore 64 power supply - reparable

Part. no 251053-11 commodore 64 power supply - reparable

Here is an image of the PSU with the bottom plate removed. The fuses can be seen on the little PCB flanking a large capacitor.

Part. no 251053-11 commodore 64 power supply - reparable

Commodore 64C & C64GS PSU #2 (Part No. 251053-11)

This particular PSU has no fuse or a power switch on the rear side.

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Commodore 64C & C64GS PSU #3 (Part No. 251053-11)

This particular PSU uses a T200mA fuse. It has no power switch on the rear side.

S/N 251053-11 Commodore 64 Power Supply

S/N 251053-11 Commodore 64 Power Supply

S/N 251053-11 Commodore 64 Power Supply

Ray Carlsen’s Computer Saver

The above PSUs use a linear design consisting of a transformer, a rectifier, filter capacitors and a regulator for the 5V DC source. The 9V AC comes straight out of a transformer. This linear design is simple and reliable but it creates a lot of heat which will eventually destroy the PSU. Some of the PSUs can be repaired while others must be replaced. One of the ways a PSU can fail is from a shorted internal 5V regulator. That fault puts excessive voltage into the computer and will most likely burn off IC’s (like RAM ICs) and kill the machine before being noticed.

Ray Carlsen have come up with a solution in form of an over-voltage protection unit to prevent damage to the Commodore 64 computer due to a failing PSU. It is called a  Computer Saver and is essentially a fast-acting electronic circuit breaker. It functions by quickly cutting off the 5V supply line to the computer if  the voltage exceeds approximately 5.4V. As a stand alone cable version it is inserted between the PSU and the power plug of the Commodore 64. Whenever there is a fault, the red diode flashes/makes a clicking sound and the PSU can be removed before damaging the computer. I always use it when connected to an original PSU regardless of its previous working state. Just because the PSU worked before, does not necessarily mean it will keep on working! The Computer Saver has already saved my precious machines from at least 4 broken PSUs which came with a supposedly working machine. Do not believe that a PSU is working just because the power LED lights up when turning on a Commodore 64! The price of the Computer Saver is far less than the price of a replacement MOS8580 SID chip…

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Ray Carlsen’s PSU with Build-in Computer Saver

Ray Carlsen also makes universal Commodore PSUs with a build-in Computer Savers. His PSUs delivers 9V AC @ 1A and 5V DC  @ 5A which is more than enough to run a Commodore 64 with a RAM Expansion Units (REU) or a SuperCPU attached to it. It features large heat sinks to make it run cool in any environment, a tight regulation from no load (computer off) to full  load (5 amps maximum) and has automatic shutdown protection if overloaded from a downstream short circuit. The electronic components are assembled in a sturdy metal case and I had Ray install an IEC power connector so I could use my own mains cable for the European 230V @ 50Hz mains voltage. My custom made version only has a power connector for the C64 while the standard version comes with a C128 connector as well. This PSU is one of the nicest peripherals I have for my Breadboxes!

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This is the inside of the Ray Carlsen PSU. Everything is kept nice and neat!

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© breadbox64.com 2016

16 thoughts on “C64 Power Supplies

  1. A very useful and well writen article about the different PSUs for the Commodore 64.
    Maybe a follow up on how to build your own in the future?
    Keep up the great work 🙂

  2. I have some PSUs which are not pottet and have screws on the bottom cover. Easy to fix. It’s the model in the middle:
    Repairable PSU for teh Commodore 64

  3. Just added a repairable PSU (Commodore 64 PSU #1 (Part No. 251053-11)) and a C64C PSU with an external fuse (Commodore 64C PSU #3 (Part No. 251053-11)) to the post.

  4. Just contacted Ray to try get one these c64 psu for uk c64c computer hopefully hear soon, not used my c64 in some years and want to keep it working for many more years to come.

  5. In my own experience, Ray was extremely fast to get everything done and shipped. I did not get the bill until after he shipped the PSU to me! I guess he trusts people 🙂 As you’ve already decided to go through the hassle of getting one of Ray’s PSU’s, I would also recommend that you consider getting a Computer Saver as well. Just in case you later on decide to use an original PSU with your C64C.

  6. Hi. I just got a C64C as a gift from an old timer 🙂 The PSU is one he** of a strange beast I can tell ya. The part number is 251053-11 (as in your list of psu’s), but it looks like this:

    Non-repairable Power supply unit for the Commodore 64 (Part no. 251053-11) Read more on breadbox64.com). Non-repairable Commodore power supply unit (Part no. 251053-11). Read more on breadbox64.com

    So, I guess Commodore really used “what is available today” kinda tactics 🙂

  7. Hi Olli and thanks for sharing. It certainly looks like Commodore was using whatever they had on the shelves when assembling their gear! It looks more like a 902503-06 than the repairable 251053-11 PSU I have in the post. I guess they used the 251053-11 part number for at least 4 different types of power supplies (a repairable, yours and two white ones for the C64C) 🙂

  8. hi all, I have just aquired a black psu part number 310200-10 and a cream/beige one with exactly the same specs but part number 902503-07.
    The black one is the same shape but has a SQUARE connector instead or round !!!! they both have the correct logo but neither of them have switches on the back.
    Any one have any ideas about the black one ? ( being square an all )???

  9. The black one is for the Commodore plus/4 system 🙂 The other one was made for the Commodore VIC20 but it should work with the C64. However, never trust an old PSU! Always test them with e.g. a computer saver like Rays or similar.

  10. Hi, sorry this took “a while”, I totally forgot I posted something here 🙂 I actually opened and repaired a “902503-06”, *which has a square fuse plate*, last year. It was a real pain to open, especially to get the regulator detached from the “epoxy” or whatever that super durable goo inside the PSU is 🙂 I didn’t not touch the 9V electronics, only the 5V side. I replaced the capacitor, and other soldered components on the PCB, but especially the regulator to a high quality Linear Technologies one. Runs like dream and much cooler than before. Unfortunately, no pics survived my phones death :/ Just to let you know.

  11. Thanks for the update and great to hear that you got it fixed – nothing beats self-success 🙂

  12. All C64 power supplies should work with your Aldi machine 🙂 However, as far as I know it was originally shipped with the beige/white version PSU (i.e. PSU Part No. 251053-11) that also came with the C64C version.

  13. There is also a new replacement power supply made by Retro Game Supply. I use it on my C64 and C64C and it works perfectly (link).

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