It feels like it’s been almost 25 years since I last messed around with something like this. Back in the day I was using a G3 B&W — not as infamous as the G4 MDD, but those machines did have the occasional PSU failure. I remember swapping out the PSU a few times myself, and by then ATX compatibility was getting decent enough to make the job easier. I bet a lot of you here have also flashed graphics cards or done ATX PSU swaps on these old Macs.
Anyway, just the other day the PSU in my G3 MT started giving me trouble. First it showed some weird graphics glitches, then after a few power cycles and restarts the power supply completely died. From my experience, simply recapping these PSUs almost never fixes them. Sometimes you can bring one back by replacing regulators and other parts, but it takes a lot of time—and once you add up the cost of parts, it’s usually way more practical just to swap in another PSU...
The pinouts are already pretty well known, but I’ve shared what I know just in case. I also sell the cables in my store, but any skilled enthusiast could make their own. If you’re building your own, feel free to use the pinout as a reference. And if your G3’s PSU ever fails, I hope this info comes in handy.
One guy replied to me on Facebook said that he had seen a post somewhere where the pinouts for the G3 MT and G3 B&W were mixed, causing confusion with the wiring. The G3MT was the first and last Mac whose logicboard was designed to use a "PS/2" PSU, which meant full compatibility with ATX(PS/2)!
If you want to know more, read my blog...
Anyway, just the other day the PSU in my G3 MT started giving me trouble. First it showed some weird graphics glitches, then after a few power cycles and restarts the power supply completely died. From my experience, simply recapping these PSUs almost never fixes them. Sometimes you can bring one back by replacing regulators and other parts, but it takes a lot of time—and once you add up the cost of parts, it’s usually way more practical just to swap in another PSU...
The pinouts are already pretty well known, but I’ve shared what I know just in case. I also sell the cables in my store, but any skilled enthusiast could make their own. If you’re building your own, feel free to use the pinout as a reference. And if your G3’s PSU ever fails, I hope this info comes in handy.
One guy replied to me on Facebook said that he had seen a post somewhere where the pinouts for the G3 MT and G3 B&W were mixed, causing confusion with the wiring. The G3MT was the first and last Mac whose logicboard was designed to use a "PS/2" PSU, which meant full compatibility with ATX(PS/2)!
If you want to know more, read my blog...
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