Amiga hardware info, help and support with a focus (but not limited to) North American NTSC experiences. Open to all.
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intric8
Seattle, WA, USA

by intric8 posted Sun Sep 10, 2017 5:28 pm

My Amiga 2000 has been my daily for nearly all of 2017 and much of 2016. It's the ultimate tinkerer machine, IMO, for the "old school" classic Amiga. The only exception to my daily use lately has been from my A1000, of which I've fallen completely head over heels. I actually have a lead on an external HDD for it which I'm trying to work out - more on that in October, most likely. But I digress...

The 2000 can take a ton of hardware additions. But over time, the more you add the more stress you put on the power supply to run everything. Eventually it can cause it to fail or make the machine actually crash.

My 2000's expansions currently include:
  • two floppy drives
  • Syquest drive
  • original 40MB HDD (boot drive)
  • scsi2sd 4GB drive
  • 8MB RAM board
  • GeForce 040 accelerator
  • laser tank mouse

That list alone is quite a bit to ask of the original 2000's 200 watt PSU, but it's been handling things OK.

The Amiga 2000 PSU supplies the following:
+5V @ 20.50A
+12V @ 8.00A
-5V @ 0.30A
-12V @ 0.30A


To reduce any stress and allow for future expansions stress-free I've acquired what's known as the Bigfoot 2000 PSU, which supplies a beefy 300 watts of power! Not only that, but it has a switch on the back which allows it to work with either 110V or 220V - so US and Europe can use this beast.

The manufacturer, Micro R&D, made PSU upgrades for the 500, 2000, 3000, 4000 and CD32.

The other big selling feature of this PSU is that it was designed to simply be a drop-in replacement with no hardware mods required to the A2000 or A2500 case.

To be quite honest, the build looks to be slightly higher quality than the C= original.
bigfoot-1.jpg
Big Foot PSU for Amiga 2000/2500, top view.
bigfoot-2.JPG
Big Foot PSU for Amiga 2000/2500, rear/back view.
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Christian

by Christian posted Fri May 31, 2019 1:53 pm

I have a Bigfoot 2000 power supply.

The case is well made, but that's about it in my opinion. I did some research back in the 1990s and was not too impressed.
Biggest issue, if I remember correctly, is that the Bigfoot power supplies do not incorporate a crowbar circuit which is present in all of the original power supplies in the desktop Amigas.
A crowbar circuit will short circuit the power supply outputs and blow the fuse and possibly the switching transistor(s).

But why is this good and why would I want one of those in my power supplies...

It is a safety feature that sacrifices the power supply and protects your computer with all of the expansion cards in the case that the voltage regulation of the power supply stops working.

Example:
Voltage regulation on the +5V output fails. Goes to +7V.

Bigfoot 2000 is ok, the A2000 and the GVP G-Force in your A2000 are completely dead - most chips are fried, some may have mechanical signs of heat failure.

Lite-On or Phi Hong -> power supply blows fuse and possibly switching transistors as soon as +5V voltage reaches +5.7V (don't remember the exact voltage) when the crowbar circuit shorts the +5V line to ground. Amiga and expansion cards are most likely ok - as long as crowbar triggers soon enough and voltage ramp up is not too fast.


The A2000 power supply outputs 20A on the +5V rail. That is plenty and at full output, the power connector on the motherboard will fail over time, especially if the tin coating on the pins/contacts is oxidized.

I will not use my BigFoot 2000 power supply. Though I am thinking of fitting an original A2000 Lite-On or Phi-Hong power supply board (I have one of those as a spare without the case) inside the case.

If someone wants to buy my BigFoot 2000, then I am willing to sell it - provided that the buyer understands the above issues.

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