In message , Steve
writes
On Sun, 18 Sep 2005 12:40:59 +0100, Ed Sirett wrote:

If you hadn't mentioned the buzzing _before_ the fan starts then I'd have
said go for the APS first. Now I'd go for the PCB first.

Out of interest, why do you say that?

I've just tried checking the impedance

Resistance (it's a switch) ... less than an ohm ish?


of the APS when blowing and not
blowing.

Are you saying you've tested the aps microswitch in the closed and open
positions?


It seems to be working correctly, but I hear a crackling sound
(the membrane inside the sensor, I assume) and was wondering if this would
have been what you thought the buzzing sound was

No, more like the sound of electricity arcing across a quickly
deteriorating solder joint

- if it happened after
the fan starts (which would cause a pressure change, hence crackling from
the APS).

Crackling and buzzing aren't really the same, are they ?

--
geoff