Hi, I have one of these on my workbench and both the fans aren't working, the switch itself is fine. On inspection it appears that an SMD component has come off the motherboard, Z1. Whether this was due to bad soldering or if it's been knocked I can't tell. There doesn't appear to be any signs of physical damage or heat. Tracing the circuit shows that the power to the fans was delivered by this component and I would suspect it was a zener. Without the original I wouldn't have a clue what the value was and these days it's highly unlikely to be marked anyway! I'm unable to find any servicing info on these boxes so in desperation I'm hoping somone might have one they could look inside. The only other 3750's we have are single fan units and the power arrangement is different. I've also left a note on the Cisco site but so far not received any replies.
Thanks Bob