Weird Pressure switch fault (continuous filling)

[hodgheg]

It was on an Amica but this fault probably applies to most electronically controlled machines. It was filling continuously despite the pressure switch clicking and metering out correctly, so, now that we’re in the era of boards deciding how much more to fill after the pressure switch has switched, I changed the board (had a spare fortunately) but the fault remained.

When I unplugged the pressure switch during the fill the filling stopped, so I metered out the switch again, this time on a mega-ohm setting. There’s the problem, flickering between 500k and 1 meg on pins that should’ve been open circuit. Presumably enough voltage could get through to fool the board. Wouldn’t’ve happened in the old timer days. Replaced the switch, fault gone.

I prized opened the switch (a normal looking Metalflex type) but no sign of condensation or anything amiss. I’ve only had this fault before on Smeg Dishwashers and then it’s always been the (horribly expensive) board.

PS Anyone come across these new pressure switches Electrolux are starting to use on their Tricity Bendix machines with a chip and some form of induction circuit IN THE SWITCH??? What the hell’s that about?

[leavemetogetonwithit]

Re: Weird Pressure switch fault (continuous filling)

I think you mean the “analogic” type, a popular topic of conversation in fault queries on this board. I think they’re fairly reliable but you can destroy them by blowing into them apparently.
Mike.

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