On Oct 1, 12:50*am, "
wrote:
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

Consider the possibility that the missing components was a chip fuse
or a fuse resistor. If one fan faulted, a fuse resistor could heat
enough to melt the solder, but it is unlikely it would drop off the
board until the solder lost all it's surface tension properties.
Likewise with a Zener. Has someone been in there before you? If not
the part may still ba floating around or stuck onto the board nearby.
I agree with others that the supply voltage and fan voltages are
likely the same.

Neil S.