68kMLA Classic Interface
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| New PCB design: 840AV/8100 Stealth ATX | |
| Posted by: croissantking on 2026-04-04 17:53:42 I wanted to share this layout for a brand new PCB that I've just about finished, one of my first proper designs. It is intended to fit like a glove inside the Delta power supply housing that's common to the Quadra 840AV and Power Macintosh 8100. These PSUs are failure-prone and notoriously difficult to repair, so I was keen to come up with a classier solution than just stuffing an ATX PSU inside the case with an adapter and calling it a day. The new PCB replicates the exact dimensions as the original Delta lower PCB. It's designed to have the internals of an ATX power supply stood off above it as a mezzanine board. I've laid it out to accept an Antec EarthWatts PSU I had available, but it could likely be adapted to other models just by adjusting the locations of the four standoff mounts. The design reuses the stock AC inlet board, and incorporates both the original monitor passthrough power relay and fan control logic. The 20/24 pin ATX harness is intended to be cut short and looped into the +12V, GND, -12V, +5V, PS_ON and +5VSB vias seen at the top of the new PCB. This is so a soft power inverter can be integrated, and also allows the original modular Mac PSU connector to be fitted in its original location. I've mocked up the design mechanically by using the old Delta PCB as a base, it's very sturdy. I'll get this sent off to print shortly. Once I'm happy the design functions as intended, I'll of course be making it available on Github 🙂  | |
| Posted by: Durosity on 2026-04-04 22:49:49 Oh this is perfect! I need to replace the PSU in my 8100 with an ATX and I was trying to figure out the logistics of getting it into the existing PSU and making it look stock! | |
| Posted by: Gothikon on 2026-04-04 23:54:02 Looking forward to seeing how this turns out! | |
| Posted by: croissantking on 2026-04-08 11:33:22 I've finally sent this off for fabrication. I thought I was about 5 minutes away from finishing but it ended up taking a few hours more. There's so much detail to oversee. | |
| Posted by: Trash80toHP_Mini on 2026-04-08 11:51:45 WOW! Great job there, love it. How many watts is that PSU and what what's the original? | |
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