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PowerTower Pro 225 Repairs
Posted by: Phipli on 2026-08-28 04:35:12 I've picked up a rough PowerComputing PowerTower Pro 225. As well as a few dents, scrapes and some rust, it is missing various parts, the CPU, Cache (sadly), PSU. Looks like someone has had a go at recapping it. It is missing a front bezel, the CD drive doesn't look like the original and it apparently doesn't chime. My first question is... What is the compatibility between these and 9500 / early 9600 (604e, not 604ev) processor cards? Do they work? If not, I'll just use a G3 upgrade, but I'd prefer to use a low end 132MHz 604 or something until I get it to chime, just in case.
Posted by: saybur on 2026-08-28 06:12:42 Congrats on the pickup! Even in rough shape that's a great find. AFAIK these are (effectively) just a Tsunami so anything that works with the 9500 should be OK. I've got the bare logic board from one of these that came with nothing on it, and was able to boot with both a 604e out of a 7300 and a Newer G3 upgrade.
Posted by: Phipli on 2026-08-28 07:14:28 I've got the bare logic board from one of these that came with nothing on it How well does it fit into a standard ATX case? If I had a bare board I've be very tempted to try to set it up in a generic modern case as a sleeper 90s PPC Mac. able to boot with both a 604e out of a 7300 and a Newer G3 upgrade. That is good news, I'll start looking into a PSU for it then. Probably will try it with whatever is around first, but will want to find something appropriate for the plus position and size etc. Apparently, for reference, the originals were 300W, although I'd recommend getting something with a lot of 5v grunt as modern PSUs are often lacking on current for the 5v rail.
Posted by: saybur on 2026-08-28 08:03:30 How well does it fit into a standard ATX case? Eh, it's close but not perfect. Not all the screws line up right in the cheap modern case I'm using (Bgears b-Voguish) but I'm not sure if that's down to this specific case, Power Computing doing their own thing, or EATX not being much of a standard. I had to use some flat plastic standoffs in more places than I like. Between that and a repurposed GPU bracket it works well enough that I'm not worried about the thing falling apart. At least the expansion cards fit right. I can share some details/pictures if there's interest. PSU wise I'm using an OCZ ModXStream Pro 600W, which is probably not a particularly good supply but it's been working fine so far. No stability issues after I fixed the weird glitch I had with the G3 card, see https://68kmla.org/bb/threads/g3-upgrade-card-checksum-errors.50009/, though I think that had more to do with the card than the system.
Posted by: Phipli on 2026-08-28 08:09:11 @saybur I found a cheap JUSTOP 500w PSU that has a 36A 5v rail. The fan is in the wrong place, but I'll see where it gets me. I have an old PC PSU that fits perfectly, perhaps I can rebuild it into that.
Posted by: saybur on 2026-08-28 08:45:05 I'd be cautious with the PSU, there are some dodgy vendors out there. Don't know if that one is good or not, to be honest, I didn't see much about it other than one person on Reddit who had a blown fuse. That said, I don't really have expertise with power supplies. If nobody else has suggestions here it might be worth looking/asking about options on the PC forums too, they obviously run into this problem more than we do.
Posted by: Phipli on 2026-08-28 08:52:23 I'd be cautious with the PSU, there are some dodgy vendors out there. Don't know if that one is good or not, to be honest, I didn't see much about it other than one person on Reddit who had a blown fuse. That said, I don't really have expertise with power supplies. If nobody else has suggestions here it might be worth looking/asking about options on the PC forums too, they obviously run into this problem more than we do. I'm reluctant to spend huge amounts on a PSU, so to a degree I will be making compromises. The issue is that expensive PSUs often have really pathetic 5v rails - even if you buy a 1000w PSU. Old PSUs... Well, I have enough problems with 20 year old plus PSUs failing so I'm not going to buy one just to rebuild it... I'll be checking the rails on artificial loads before I run it from it, but to test a machine that might not even work, I'm happy enough to use something from the budget end of the market.
Posted by: saybur on 2026-08-28 09:02:58 Totally fair, and testing on the bench seems smart regardless. It was a few years go, but I vividly remember a nice power supply giving up the smoke after like 2 days of service. No damage but it was definitely exciting. Even name brand is no guarantee! 😆
Posted by: Froggy814 on 2026-08-28 09:06:12 pathetic 5v rails What is not pathetic? 3.3V rails? 5V is just as important, (or so I thought)
Posted by: Phipli on 2026-08-28 09:10:29 What is not pathetic? 3.3V rails? 5V is just as important, (or so I thought) 90s macs had most of the power through the 5v rail. 5v was often rated for in excess of 35A. Very few modern high end PSUs provide anything near that kind of 5v current. This is because the big loads aren't 5v loads any more. They drifted to 3.3v, but I understand that some more modern power supplies just provide 12v and there are DC to DC converters on the motherboard - although I might have misunderstood that.
Posted by: Phipli on 2026-08-28 09:13:40 Considering this is about 400w, you'll struggle to find anything modern that provides 40A at 5v. This is an 8600 or 9600 power supply.
Posted by: Froggy814 on 2026-08-28 09:17:07 Okay. That is a lot of amps... I didn't realize! Thanks!
Posted by: Phipli on 2026-08-28 09:21:13 Okay. That is a lot of amps... I didn't realize! Thanks! It's the big challenge with beige PowerPC macs. The powers crept up and if you decide you want to adapt a modern PSU to run one, you struggle to find something that matches. Generally it isn't the end of the world if you aren't running 5 disks and 6 PCI cards in a multi processor system, but I prefer to repair originals to trying to use modern power supplies. My issue in this specific case is that someone has taken the original PSU so I don't have a starting point to repair.
Posted by: Phipli on 2026-08-28 10:51:02 Well, here is some good news. I tried powering it on and the fans spun up etc but like the seller said, no chime. I poked a non-bootable floppy disk in it to see what it would do and it spat it out... Oh, code is executing then, it is trying to find an OS... So I grabbed a cable and plugged it into my amp and speakers... Booooooong So I moved it over to where I have a monitor... Plugged in a ZuluSCSI Pico... Oooh... Yay! Right. Now to shut down because I'm only running it off one of those PicoPSUs and a 60W brick. Cough. Worth restoring though!
Posted by: saybur on 2026-08-28 11:12:32 only running it off one of those PicoPSUs and a 60W brick 🤣 Love how tough these things are. Really glad you got it running!
Posted by: Phipli on 2026-08-28 11:28:54 🤣 Love how tough these things are. Really glad you got it running! Well, the 604e is using less than 10w, I intentionally picked a low power video card (a VillageTronic MPDD+) and didn't connect the CD or any hard disks, so that probably leaves plenty for the chipset and fan. But yeah, I didn't run it any longer than booting and checking System Profiler. I could have put an under locked G3 upgrade in it 🤣 They only use a couple or three watts anyway, bet they hardly use anything at 100MHz. They're a handy thing to have in a drawer though 🙂 last time I used it I made an adapter to power an Acorn RISC PC board.
Posted by: saybur on 2026-09-01 11:24:35 Just wanted to add that I really enjoyed your blog post on this, thanks for putting that together. Was a fun read over lunch!
Posted by: obsolete on 2026-09-01 13:33:00 Just wanted to add that I really enjoyed your blog post on this, thanks for putting that together. Was a fun read over lunch! I agree, writing stuff out in blog format like that is a lost art and I enjoy seeing it done well.
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