So... I tore it off a PowerMac 4400/200 that I'm trying to repair. Currently I'm at the stage of eliminating factors that would keep the thing from powering on (RAM is fine, HDD and peripherals are fine, no obvious damage on motherboard).
Problem is, I know precisely nothing about AT-era PSUs and this particular one is an oddball at that. It's got the two auxiliary power connectors that according to schematics online have three +3.3V power lines (and ground obviously) along with a connector that goes to a "SOFT PWR" connector on the motherboard so apparently it's not like the other ones that power on as soon as they're plugged in.
I took some pictures of the back of the board... I put them in an imgur album. I can attach them here if imgur albums are a problem.
The current problem with the power supply, is that it makes a buzzing sound when I plug it in. I'm not an expert, but another AT PSU that I've had was silent (aside from the fan). I also don't know how to make this particular PSU power on on its own so I can test its outputs.
If it turns out that the thing is completely blown, can I modify an ATX PSU to give out the same kind of outputs? I think the -5VDC and the multiple +3.3VDC are going to be a bit of an issue... although I guess I could use the +3.3VDC from the MOLEX connectors...?
Problem is, I know precisely nothing about AT-era PSUs and this particular one is an oddball at that. It's got the two auxiliary power connectors that according to schematics online have three +3.3V power lines (and ground obviously) along with a connector that goes to a "SOFT PWR" connector on the motherboard so apparently it's not like the other ones that power on as soon as they're plugged in.
I took some pictures of the back of the board... I put them in an imgur album. I can attach them here if imgur albums are a problem.
The current problem with the power supply, is that it makes a buzzing sound when I plug it in. I'm not an expert, but another AT PSU that I've had was silent (aside from the fan). I also don't know how to make this particular PSU power on on its own so I can test its outputs.
If it turns out that the thing is completely blown, can I modify an ATX PSU to give out the same kind of outputs? I think the -5VDC and the multiple +3.3VDC are going to be a bit of an issue... although I guess I could use the +3.3VDC from the MOLEX connectors...?
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