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Commodore Amiga 500 full replacement Power Supply

Commodore Amiga 500 replacement Power Supply


This is a full replacement of the power supply of the Amiga 500 with a similar one of the last generation. This type of switching power supply fits perfectly inside the case of the original psu.

The repair will not be made because this psu is very common at very low prices, i don’t waste even a second to find the multiple faults, i prefer devote to other things less common.

  1. Martin Paoloni
    June 16th, 2014 at 03:38 | #1

    This has to be one of the greatest blogs out there. Please, keep it up. And thanks for all your awesome posts!


  2. qdx
    June 17th, 2014 at 16:27 | #2

    Amazing ! Any good online seller of this T-40B shipping worldwide ?

  3. Juri
    July 26th, 2014 at 22:39 | #3

    @ qdx

    good online seller is mouser.com

  4. Rave
    April 12th, 2015 at 14:42 | #4

    Just in case any one is interest the T-40B has been retired and replaced by the RT-50 now.


    I have just completed this mod with the above PSU.

  5. Howard
    May 6th, 2015 at 03:19 | #5



    Which model RT-50 did you use? Can it also be use on the A1200 model?



  6. December 28th, 2015 at 05:42 | #6

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  7. Mech
    February 27th, 2016 at 06:18 | #7

    Why use a power supply that is weaker than a A500 psu originally was.. +5v was 4.5amp on A500psu and +5v is what is important. You are in effect making it as weak as A600/1200 psu. While it will work for most machines, heavily expanded ones may have problems.

    Another thing to consider is many of these caged psu’s were designed to be in a fanned enclosure,and although the 500 might only push the specs,this should be considered. The data sheet should indicate if a fan is needed.

    Mean well makes some terrible psu’s(not all). Many have high ripple and some come with poor quality caps. As usual check the datasheet.

    I hope this doesn’t come off as negative,i just want to point out the facts to users.

  8. February 27th, 2016 at 10:55 | #8


    This is just an example of how you can do, certainly i will not use this power supply 24h switched on.

  9. November 14th, 2016 at 17:02 | #9

    Ma saresti in grado di farne uno per un A1200 che monta PPC e Bvision?

  10. November 19th, 2016 at 10:20 | #10


    Ciao Mikro

    Questo ALIM dato il basso amperaggio non va bene su 1200 carozzati , va benissimo su un 500/600/1200 liscio senza nulla, per la tua situzione ti consiglio di optare per modifiche con ATX, vedi post:


  11. William
    April 24th, 2017 at 12:49 | #11

    Esiste qualche dettaglio in più di questo progetto?

  12. Solo761
    January 28th, 2018 at 22:57 | #12

    A bit late to the party… I have RT-50B that I’m trying to use in a project with one loose A500 motherboard. It works and powers it up fine, but I have slight waves going across my monitor that I don’t have when using normal Amiga PSU, aka noise. Is it possible to get rid of it, or that’s just how it goes when using these kinds of PSUs?

  13. January 29th, 2018 at 16:21 | #13


    Hi Solo,

    mhhh nope, here with the T-40B works perfectly , tried some years ago with A500 and A600 (without internal/external additional cards)

  14. mxa
    February 1st, 2018 at 10:17 | #14

    Excellent job with the pictures. One question though, what did you do with the large black cable (in IMG_1402 & 1406?) I.e, the one which comes out together with the five connectors on the left/DC-side (and was soldered onto the other side on the original PSU)? I can’t see where it goes, and it’s not hooked up to any of the terminals on the new PSU, AFAIKT. (It disappears in the rightmost corner of pic IMG_1402 – http://www.nightfallcrew.com/wp-content/gallery/commodore-amiga-500-replacement-power-supply/thumbs/thumbs_IMG_1402.jpg

    Thanks again for documenting this. Guessing a lot of Amiga owners are going to replace their ailing with a new Meanwell PSU.

  15. February 1st, 2018 at 14:54 | #15


    Yep, it’s the “shield”


    You don’t need this butthe design of the original PSU is like this.


  16. mxa
    February 2nd, 2018 at 18:28 | #16

    Thanks for clarifying that @Dave. I guess I’ll just cut off (& terminate) that cable then. I was thinking of hooking it up to ground (based on suggestions from others), but not sure if there’s any real benefit in this.

    btw-it’s funny how all the pics and the videos (that I’ve seen so far) omit this little information as that cable is quite prominent. :)



  17. Eriond
    April 23rd, 2018 at 13:16 | #17

    Just for info, I’d recommend the MeanWell RPT-75B because it has superior specs (6A on the 5V rail), and fits the case good enough. You will however have to make your own mounting plate to accommodate for the new hole pattern of the PSU. I will post such an adapter on GrabCAD for those who have a 3D printer nearby. So far I have converted 3 of mine PSUs, and they can power any hungry accelerator, disk or memory expansion without breaking a sweat… :-)
    Link: https://www2.mouser.com/ProductDetail/MEAN-WELL/RPT-75B?qs=%2fha2pyFaduj89TKwmmRVV00hY%2fzVMNOqNSgmhXyUhX0%3d

  18. April 27th, 2018 at 23:14 | #18

    Mean Wells RT-50B is plenty powerful enough with its max 5A rating on 5V line. Keep in mind it requires minimum 0.2A load on +12V for stable operation, so a power resistor (39 Ohm, 5-10W) should hjelp. You can do the same for the -12V with 82 Ohm 3W if you want. My A500 psu was fine, so I just recapped it.

  19. mxa
    July 5th, 2018 at 15:57 | #19

    Anyone know if the RPT-75B also has the 0.2A minimum requirement on the +12V line?
    (Yes, I still haven’t mounted my RT-50B yet – way too many projects in the air)

    Contrary to other claims about being a drop-in replacement, the RT-50B also does not fit in the case via any mounting holes so either drilling or making a simple adapter plate is required. Its size was the main reason I got it (and the reduced hassle of having to modify the chassis, which turned out one still had to do!) :)

  20. mxa
    July 5th, 2018 at 16:51 | #20

    Well, to answer my own question :p it appears this is indeed the case according to the datasheet for the RPT-75B – 0.2A minimum on the +12V line & 0.1A on -12V (& 0.6A on 5V)

    So on paper, it does not seem to be much of a difference (although 0.6A on 5V might actually be a drawback)

    In this regard the RT-65B is probably better, with min req of 0.5A on the 5V line, 0.2A on 12V (same for all) and 0A on -12V.

    Sorry for the extra noise. But if anyone has encountered any practical differences/benefits it would be useful to know.

  21. October 4th, 2018 at 19:23 | #21

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