RE: [cobalt-users] changing fan by PSU on RAQ3i

["Phil Beynon" <Infolink@xxxxxxxxxxxxxxx>]

> I have one question here because my raq3 have a problem with fans....
> (fans seem to not work... BOTH ! which is strange...)
>
> Are fans in raq3 temperature dependent ?
> Are they supposed to work all the time ? even when you light on the box ?
>
> The strange thing, isnt a temperatude daemon ? any temperature log inside
> the box to monitor the temperature ? since a daemon start when you start
> the machine... I imagine there is something somewhere...
>
> Thanks
>
> Master Phil

Generally speaking temperature self sensing / reporting fans have 3 wire
connections, "on always" have two.
There would be no point in having a sensor actually in the fan as this would
be cooled by the fans motion.
It's pretty rare to use off-fan circuitry to control the speeds on DC fans,
the only thing that comes to mind which uses this is older Textronix 'scopes
(400 series at least).
If you get a "no-start" or twitching fan then replace it and bin the old
one, if you get a "sometimes start" fan it may just be dusty or it may have
been twisted slightly causing it to bind - pretty common on PC cpu fans on
cheap heatsinks.
Make sure you use a computer grade fan as a replacement, some types can
radiate from the motors causing noise in adjacent wiring / PCB tracks.
If you are working on or near a switchmode power-supply be careful - they
bite - from experience!

Phil