QuadrATX PSU mod for Quadra 900/950 soon available

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BadGoldEagle's picture
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QuadrATX PSU mod for Quadra 900/950 soon available

Hi all,

Even though this is my first post here, I'm not new to classic Macs. I've been a regular poster on the 68kmla since 2014. I knew of this site for a while but never thought about registering until now. 

Anyway, my Quadra 950's PSU blew up a couple months ago after a complete recap. While trying to find a solution online, I noticed that I wasn't the only one with this rather annoying issue, so I decided to fix it once and for all by designing an ATX PSU adapter I called the QuadrATX 9x0. 


The kit consists of two boards, one for AC (which includes a power line filter, a relay and a fuse for the monitor plug) and the other for DC (for ATX->Quadra pinout conversion, Softpower "translation", and it features hard drive plug adapters as well as a fan controller with a thermistor). No modifications to the original boards necessary. 


Boards installed in the original casing. Original mounting hardware is used to secure them into place. 

The ATX PSU will be mounted sideways using new standoffs: this won't be visible once installed in the Quadra and it's the only modification that needs to be done to the PSU. 

Holes aren't a big deal though if you ever decide to fix the old original boards and put them back in. 


I'm not done with this project yet, I've got to solder everything, do some extensive testing and mount the PSU before I make kits available to other hobbyists. I ordered 15 sets with JLCPCB and they just arrived today. I still have a few available (ie not reserved). Would someone here be interested? A kit will cost $8 and will come with the fan controller chip (ATtiny 25) as well as the AC "line" post/connector (the original plug is hard to find and I have enough to make 100 sets now). Electronic parts will settle you back about $60 (Arrow.com) and you'll need an ATX PSU with a strong 5V rail (I will measure the actual LB power consumption and come up with an absolute minimum amperage later)


I'm posting this here because of the reason above but also because I'd be interested in buying a Powermac/Workgroup Server 9150 (which has the same PSU). See my other thread for more details. 


PS: Everything is open source, you'll be able to download and edit the PCB files to your liking one I'm done with the design phase.