Power Mac 8100 Power Supply

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Power Mac 8100 Power Supply

Can anyone provide the power connector pinout specs for the 8100 motherboard? I need to re-wire a atandard ATX power supply to connect to the 8100 and aside from the +5v, +12v, -12v, and GND connections, I need to identify the function of the remaining three pins. No, I do not have a working power supply available to test from. From what I've been able to gather from online searching, the pin next to the +12v pin is the turn-on signal output to the PS, and the pin next to the last +5 wires is the +5v TRKL input. That leaves the pin next to the -12v pin, assuming the info on the other two pins is correct.

Many thanks for any assistance!

Power mac 8100, Mac OS 8.6 or Earlier, Power Supply

Posted on Sep 22, 2009 10:38 AM

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Answer 1

Oct 30, 2009 11:27 AM in response to CraigGeorge

I've just taken apart a Mac 8100, intending to use the PSU to power an external disk drive. The PSU has the following outputs:

+5V 30A
+5V (TRKL) 0.1A
+12V 5A
-12V 0.75A
Maximum output power: 200W

There is no switch on the PSU, both switch-on and switch-off being made by momentarily pressing SW1 on the motherboard.

Wires between the power connectors on motherboard and PSU are coloured:

01-04 Red +5V
05-09 Black 0V
10 (not connected)
11 Blue -12V
12 Yellow +5V Trickle
13-16 Red +5V
17-20 Black 0V
21 White on/off
22 Orange +12V

The PSU also has wires with 4-pin connectors for disk drives, etc. Negative wires are black, +5V wires are red and +12V wires are orange.

I do not have details of the on/off circuitry so, to be safe, I connected a 1KΩ resistor to pin 21. Touching the other end of this resistor to pin 12 (+5V trickle) started the PSU, and touching it to a 0V pin switched it off. This PSU appears to work correctly with no load connected.

To use the PSU away from the motherboard, I shall permanently connect +5V to pin 21 via a 1KΩ resistor, and use a toggle switch for on/off.

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