There are a number of power supplies that Commodore produced for the A500. The A500/A600/A1200 can all use the same power supply. Keep in mind that you may need more juice if your Amiga has accelerator cards or Zorro cards hanging off of it.

I found one A1200 with a full size 3.5“ hard drive shoved inside (see — http://retroninja.net/a1200). They tapped the HDD power off of the FDD. The external FDD did not have enough juice to work. Only so much power can be pulled through any motherboard

• Type1 - Heavyweight PSU manufactured in Germany might also be a 4.5A PSU
• Type2 - Lightweight PSU manufactured in Malaysia

Amiga 500 600 1200 connectors.

• Gauge Opinion - this is a thread I found…
  • Reusing an Amiga case is nice since the five pin plug and cable are already there. However, the wires in that cable are pretty thin, same as in a C128 PS cable… copper is expensive. Commodore got around that by installing a sense” line, the fifth wire in the cable. It provides feedback to the PS board so that when the load on the +5VDC is increased (computer on) the PS feeds out a little more voltage to compensate.
  • The new power module has no such sense line, so I use heavier gauge wire to minimize the voltage drop in the cable.
  • I wonder how those modified Amiga power supplies would hold up when the load is very heavy… when the user has added enhancements such as extra RAM, hard drive and CPU accelerator.
  • I use #16 wire in a 5' cable to feed a C128 and go to #14 for longer runs or to feed an Amiga which I know to be a power hog.

• motherboard connector is a Molex 2139 KK 3.96MM 14pin
• wire is 18ga 300v from power supply to mobo
• the standard rating is a 200W power supply
• with no load (mobo or power supply), if you turn on the power supply you should see the fan spin but then stop; with FDD(s) attached the power supply will stay on, along with a constant spinning fan
  • can someone test if mobo connector +5V and +12V is actually off with no load?

• This system requires a 'tick' circuit which provides a 50/60Hz +/-10% reference signal to the video chipset or motherboard jumper J300.
• Would require a simple linear regulator circuit using a 7905 or equivalent, to generate -5V.
• At motherboard location J300, cover pins 2 and 3 with a jumper to internally generate TICK signal
  • from AmigaKit adapter
  • is this just their hardware adapter or all atx adapters?

Sadly, you can't just substitute any ATX in for the A2000, see below. There is a small after market for replacement power supplies. See the A500 Power page for an easy Cisco swap.

Meanwell

Meanwell has become a standard for replacing power supplies for the 8 and 16 bit lines.

• MPQ-200B
  • medical rated, high quality + high cost
  • rated for 200W
  • output
    • +5V at 15A (vs 20.5A output of A2000 power supply)
    • +12V at 7A (vs 8A output of A2000 power supply)
    • -5V at 2A (vs .3A output of A2000 power supply)
    • -12V at 2A (vs .3A output of A2000 power supply)
• RQ-125B
  • only 125W!
  • output
    • +5V at 11A (vs 20.5A)
    • +12V at 4.5A (vs 8A)
    • -5V at 1A (vs .3A)
    • -12V at .5A (vs .3A)

Here's the standard PC power supply to compare to Amiga's needs. Nowadays, there is seldom a -5V power line. If you can find an old AT power supply you're almost guaranteed a -5V. Keep an eye out at yard sales and thrift stores. A quick and easy indicator is if a 5.25“ or 3.5” drive is in the PC. This usually means it is an old power supply so the -5V may be there.

• /PSON activated by pressing and releasing the power button while the power supply is in standby mode. Activating /PSON connects the power supply's /PSON input to ground, thereby switching the power supply to full-on condition.
• 18 AWG is recommended for all wires except pin 11, which should be 22 AWG. For 300W configurations 16 AWG is recommended.