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Seattle, WA, USA

Amiga 2000 PSU and KS upgrades, almost

by intric8 Mon Mar 12, 2018 8:06 am

After hearing what tastemakerChuck was up to with his A2000 (fan swap, etc.) it inspired me to get off my butt and do some upgrades of my own that I'd been planning for several months. I had all of the parts, I just lacked the motivation.

The first upgrade was to swap out my rather noisy stock PSU and put in the super solid and mostly quiet Big Foot PSU, made in Loup City, Nebraska.

Living in the Pacific Northwest, naturally I needed a Bigfoot:
The bigfoot 2000 is a 300 watt replacement power supply for the A2000. It's completely designed as a drop-in replacement for the existing power supply so is guaranteed to fit, without alterations to the A2000 case being necessary.

The first thing you notice when you pick it up and compare it to the stock PSU is that this piece of kit is really well-made. It's almost a shame it gets tucked into the case as it's really nice looking for a PSU.

Anyway, I figured last year when I acquired it that since I was adding a couple of extra bits here and there, a little extra juice wasn't a bad thing. Plus the Bigfoot I found was NOS.

It really was a drop in affair and installation was seamless.

Then I turned it on. My video feed, for some reason, was receiving interference. Large bands were slowly strolling vertically across my CRT monitor. I couldn't believe it! Peeved, I turned everything off and picked up my original PSU. I figured, "I'm already this far, I might as well just fix my old one." So I pulled the old PSU apart and swapped fans with a new, high-capacity near-silent fan that I'd used in the past and buttoned it all back up again.

I pulled the Bigfoot out and ... that's when I noticed something I'd never really paid attention to before. There is a little switch on the back of the bigfoot which allows you to swap the voltage! A huge improvement over the stock PSU, I could swap from 110 to 220, and it was set to 220! I flipped the switch to 110 and powered back up. Everything was totally fine!

So, I put my newly refurbbed old PSU on my rack in storage. A win! And my old PSU is ready for near-silent business as a solid backup.

On to project number 2: adding a Kickstart Switcher. Since I was all the way down to the PSU/FDD sled, pulling it up and out the the way was no big deal.

I have two KS Switchers in my possession.

One is from Jim Drew @ CBMStuff. The other is a NOS from ICD called the "Kickback ROM". Honestly the ICD unit looks like something from a highschool electronics project.
Kicksart Switch from CMBstuff/Jim Drew

What I wanted to do was put my KS 1.3 in as the primary and KS 2.04 as the secondary. I have a small handful of programs and utilities that were written for 2.0 that I'd like to poke around with.

Depending on where you attach the clip leads would determine which button you press to activate the other ROM.

I tried the Jim Drew board first. After getting everything in place, firing up the machine would produce a purple screen. This is a color not even identified by C= in their original list of color screens (I looked).

I tried a few different clip lead options (there are multiple locations you can use) and never was able to boot. I little confused, I moved the KS ROMs over to the ICD board instead.

Same result.

With the ICD board instead of clipping to Gary or Paula or CIA chips, there was only one wire. And it was to be clipped to #18 on the CPU.

That got me to wondering. I'm bypassing the CPU entirely because I have the GeForce 030 plugged directly into the CPU slot. I wonder if using the CPU slot makes using the KS Switchers out there null and void? That doesn't really make sense to me with the CMB board, but it would make sense to me in the case of the ICD board. The lead wire going to #18 on the 68000 is going to a chip that is already bypassed, so maybe that breaks things?

In hindsight, I should have pulled the CPU card out and tried again. But since I have no intention of running without that card, it would have answered a question I suppose but not really solved my problem.

Ah well. Can't win 'em all (and it's not like I was dying to have 2.04 running, but it would have been cool).

I'm going to ping Jim Drew and see if he's ever seen this behavior before with other customers over the years. He made the KS Switch, I think, back in 1991.
User avatar
Seattle, WA, USA

Re: Amiga 2000 PSU and KS upgrades, almost

by intric8 Mon Mar 12, 2018 11:14 am

It does appear the GeForce card remaps the Kickstart ROM. That would certainly explain things.
Screen Shot 2018-03-12 at 11.17.59 AM.png
User avatar
New Jersey, USA

Re: Amiga 2000 PSU and KS upgrades, almost

by LambdaCalculus Mon Mar 12, 2018 11:55 am

Even if it doesn't work, there's still valuable knowledge to be had from the experience! Kind of a shame that the GeForce messes with the KS switcher, though.
Own: Amiga 500 (NTSC), Amiga 4000, Mac Mini G4 & iBook G4 (MorphOS), ThinkPad T40 (AROS), R.Pi3 (Amibian)
After: Amiga 1200, Amiga 600
User avatar
Seattle, WA, USA

Re: Amiga 2000 PSU and KS upgrades, almost

by intric8 Mon Mar 12, 2018 1:41 pm

Yeah, that was my takeaway, too. The benefits of the GeForce vastly outweigh the luxury of having a KS Switcher. But it would have been a nice thing.
User avatar
Zippy Zapp

Re: Amiga 2000 PSU and KS upgrades, almost

by Zippy Zapp Mon Mar 12, 2018 2:36 pm

Purple bootup, doesn't that have to do with Kick Start 2.04 - 3.1? That is weird. I have seen this before in the past with another device I have that plugs into the CPU slot. I don't have it in front of me but it is made by Supra and has an accelerated 68000 or 68010 on it.

EDIT: This is it here, Supra Turbo 28 ... spx?id=212

I need to see if I still have the disk and manual to this thing. I still have the switch and backplate that the switch is mounted to. Hmmm. My memory is worse then the 3.5 DD disks that always seems to give me errors. Heh.

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