- Supermicro power supply dimensions
- Compatible? PCB edge connector: Amphenol 10035388-102LF
- 4 pin disk drive power connector (TE 641737-1)
- 4 pin fan connector (Molex 47054-1000)
- PWM fan specification
Looking from front of case, 7+7 signal pins (top + bottom), then 9+9 pins of +12V (top + bottom), and finally 9+9 pins of ground (top + bottom)
There is what appears to be an 8 pin JST connector on a vertically mounted daughter board near the left edge of the card edge connector with a cable that connects to the twin fans. Disconnecting the cable causes the power supply to error on startup. Probing it with a multimeter shows the following: (numbering from the left/bottom pin of the fan connector on the pcb)
- ~200 Hz square wave (tachometer? 2 counts per cycle?)
- ~150 Hz square wave (tachometer? 2 counts per cycle?)
- +3 Vpp square wave ~30% duty cycle 50 kHz (PWM control?)
- +3 Vpp square wave ~30% duty cycle 50 kHz (PWM control?)
- 0V (ground?)
- 0V (ground?)
- +11.75V (power vs. power sense?)
- +12V (power?)
Hypothesis: this is likely to be a variation of the standard 4 pin fan connector, in which case it should be possible to simulate a fan by connecting two NPN transistors with the collectors connected to pins 1 and 2, the emitters connected to ground/pins 5 and 6, and the gate connected to a ~200 Hz square wave. I would still need to provide sufficient airflow to keep the power supply cool at full load, of course (or, if that proves to be too noisy, use the PWM outputs from pin 3 & 4 to be able to ramp up the fan speed when needed).