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G5 Power supply out...now what?


Well-known member
I spent the morning taking apart a 2.3 ghz DC G5 power mac this morning. It made no noises or lights what so ever  and the power supply made no click when plugged into the wall. After searching online, I thought I could at least check the fuse. I can see one end of it with the other covered in grey glue and it is not accessible without tearing down the power supply through the goop. Not sure how or if to proceed.




Well-known member
To me it sounds like you don't yet know whether it is the power supply or logic board. The best thing to do is bench test the power supply:

In order to manually start up any PSU, you just ground the green wire. Here's the pinout for the G5 PSU-

Power Supply P1 Connector
Pin# Signal Color -- Pin# Signal Color
1 +5Vstb Purple -- 13 GND Black
2 GND Black -- 14 Power ON Green
3 FANtach White/Yellow -- 15 GND Black
4 GND Black --16 Reserved
5 Reserved --17 GND Black
6 GND Black - 18 RTNaud(GND) Black
7 +12Vaud (12V2) Yellow - 19 GND Black
8 GND Black -- 20 +5V sense Red
9 +3.3V sense Orange -- 21 GND Black
10 GND Black -- 22 -12V Blue
11 GND Black -- 23 GND Black
12 Reserved -- 24 Reserved

Power Supply P2 Connector
Pin# Signal Color -- Pin# Signal Color
1 +3.3V Orange -- 9 +5V Red
2 +3.3V Orange -- 10 +5V Red
3 +3.3V Orange -- 11 +5V Red
4 +3.3V Orange -- 12 +12V3 Yellow
5 Reserve -- 13 +12V3 Yellow
6 +12Vfan Yellow -- 14 +12V1 Yellow
7 +12Vfan(12V2) Yellow -- 15 +12V1 Yellow
8 +25V White -- 16 RTNfan(GND) Black

Power Supply P3 Connector
Pin# Signal Color -- Pin# Signal Color
1 +5V Red -- 5 +5V Red
2 GND Black -- 6 GND Black
3 GND Black -- 7 GND Black
4 12V2 Yellow -- 8 +12V2 Yellow



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Well-known member
I guess this is a 750 or 1000 watt supply....these are the only two connectors....on P2 pins 6 and 7 are green...I jumped them to black (only one at a time, not both at the same time) and nothing happened