On Wed, 4 Aug 2004 13:08:49 +0100, "James"
wrote:

"sPoNiX" wrote

Check whether the programmer/timer is linked to a controller board.
Generally this is hidden away underneath and is difficult to see. This
may have an intermittent fault or may be getting damp or indeed there
may be something amiss with the wiring.

Do you mean some type of electronic controller board? I suspect the
machine is too old for such a thing (15-20 years old) although I have had a
good look I can't see anything like that.

-The Pressure switch works (as best I can tell). I disconnected it at
the
drum end and blew gently into the hose. I could hear three distinctive
'clicks' depending on the air pressure I applied).

Check the switch contacts with a meter. Also check there isn't a
blockage in the 'spigot' that joins the hose to the drum (Poke a piece
of wire up the hole if needed)

I checked the pressure switch contacts with a meter. There are 9 wire
connections (labelled 11,12,13; 21,22,23; 31,32,33) on the pressure switch
which seems to indicate 3 switches (each with 3 contacts). They are wired
such that all the three switch centre poles (12,22,32) are wired together in
parallel, all the NC (normally closed) poles (11,21,31) are wired separately
and all the NO poles (13,23,33) are wired together in parallel. eg:
11-
-12
13-
In the quiescent state 12-11 is NC, 12-13 is NO.
When I blow & hear the 'click' for that switch, 12-11 opens but 12-13 does
not close?
It's exactly the same for the other two switches? Could this indicate a
faulty pressure switch but if so why would all three NO contacts fail?

I also check for blockages as you suggested but it looks fine.

The three switches should, iirc, all come on at different pressures
but should otherwise behave in the same way.