I am trying to use the fan connection (JP1) on the RB850Gx2. I have soldered pins to it (square pad = GND, round pad = +5V) and attached a small fan (5V, max 0.1A). But the fan does not start. Also I can not measure any voltage on the pins. Is this connection connected to the 5V rail on the Routerboard? Do I need to do any configuration in order to make it work? I have tried to change various fan settings under /system/health, but nothing happens.
Did you use a multimeter and there was no voltage on the pins ?
Yes, exactly. I also measured the resistance between the pads and GND (the shell of the ethernet port) to find out which one was connected to GND. Turned out to be the square one.