ATX powersupply conversion for B&W G3

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Hawaii Cruiser's picture
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ATX powersupply conversion for B&W G3

I've got a B&W with a bad power supply. According to this page the only modification that needs to be done to an ATX power supply to make it work in a B&W is to snip the -5V wire. On this page about converting an ATX for a Sawtooth (which has the same pinouts as the B&W) the author instructs to splice the -5V wire to a ground wire and the P.G. wire to a +3.3V wire. The first author makes no mention of the P.G. wire at all. Does anyone know if the second author's splicing instructions are necessary. I've got a Dell ATX PSU which doesn't even have a -5V wire, so if the first author is correct, then I wouldn't need to modify the Dell PSU at all.

I'm inclined to believe the second author more because the first author states on another page here that any ATX powersupply works unmodified in a Beige G3, but when I hook the two ATX powersupplies I have to my Beige G3 neither works at all.

The pinout comparisons can be found here.
I've not found a chart anywhere showing the pinouts for the Beige G3.

Jon
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The Beige has a jumper by the

The Beige has a jumper by the PCI slots that is either set for Mac or PS/2. Set it for PS/2 to use an ATX PS and Mac to use an Apple PS.

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The Sawtooth and B&W PSUs are

The Sawtooth and B&W PSUs are not the same, differing by the PG/3.3V line as well.

I've done the ATX to B&W conversion myself, and it works just fine. I used an ATX extension cable - partly because the PSU cable wouldn't reach the logic board connector, and partly so that the PSU's connections would remain intact with the cut being made on the extension.

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So are you saying that the on

So are you saying that the only modification needed is the -5V snip? What about that +3.3V input for the pin on the B&W where the P.G. wire is (pin#8)? Here's a page with the ATX/B&W pinout comparison. The pinouts for the B&W there look identical to the ones for the Sawtooth.

That's interesting that the first author doesn't mention the jumper change to PS/2--an important detail! It is mentioned near the bottom of this page by another author. It's also interesting to learn that the Beige G3 motherboard was first intended to also be used by the clones, and with 603/604 ZIF processors. That's the reason for the ATX compatibility option. The returning Steve Jobs killed that intention. There never were any 604 ZIF processors manufactured, right?

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Vell, maybe I'm wrong about t

Vell, maybe I'm wrong about the difference between the B&W and Sawtooth PSUs. I just assumed so because of the different write-ups.
But I do know the -5V snip works fine.

The beige G3's an interesting board...you can see the pins where the 604 was intended to go, and the PC-style floppy port...but AFAIK the 604 option never appeared.

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