From: rickk@letterectomyTELUS.net
In article ,
jfields@austininstruments.com says...
> On Sat, 10 May 2008 03:49:31 GMT, Espressopithecus (Java Man)
> wrote:
>
>
> >Like more espresso machines, mine has a pressure switch connected to the
> >boiler that "tells" the relay to close whenever the temperature in the
> >boiler is below ~ 225F, and to open when the boiler exceeds ~ 235F. The
> >switching device that does this is functioning normally. I can't tell
> >how to troubleshoot this danged thing. I could always buy a new master
> >control board, but the darned thing is $483, and I don't really want to
> >buy and install it, only to discover that it wasn't the problem.
> >
> >Is it conceivable that the circuit board might have a function
> >programmed into it to open the relay in the event of a high current
> >reading (I.e. short)??
>
> ---
> Yup, but probably anything higher than, say, 12 or 15 amps or so...
> ---
>
> > Wow, I'll bet that would burn the contacts!
>
> ---
> Not likely. You'll have the wiring resistance in there, so current
> will be limited somewhat by that, and the heater is running on AC, so
> once the relay opens any arc formed across the contacts will be
> quenched when the voltage across the contacs goes through zero.
>
> Since you know you have a bad heater and you're going to have to
> replace it no matter what, what I'd do would be to buy a new one,
> install it, and see what happens.
>
> Short of that, if you have an appliance (laundry iron, hair dryer)
> which dissipates 1200 watts or so, say +/- 10%, I'd hook it up in
> place of the heater, momentarily, just to see if the relay maintained
> its clicking behavior. If it did, I'd suspect a problem with the
> controller in addition to the one with the burned-out heater.
>
Thanks -- that is a common-sense and practical suggestion even I can
try. I'll do it.
Rick
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