31-01-2016, 10:32 PM
Naturally, there are no schematics available for these machines. So producing one was the first objective.
The mains comes in and goes straight to the main controller. From there, wires go off to the heaters, motor, condensate lift pump, door sensor, etc. And there is a second control box. This is powered from the mains (post main power switch), but that's just about all I could establish at this point. It didn't seem important. A visual examination (plus a few in-situ tests) failed to raise alarm bells, so back together it went.
Using a plug-top power meter, I was able to confirm that the heater wasn't running. Well, not quite. Shortly after starting a program, the heaters do indeed come on. After a delay - perhaps 10 to 20 seconds - they go off, and don't come on again at all.
I took the back off and removed the heater assembly. There are 2 heaters - each one a kW - and there are 3 thermal breakers. There's one per heater, plus a third for the common return of both heaters - presumably a failsafe. And there's a 4th object that looks exactly like a thermal switch, but is actually an NTC thermistor that goes back to the main control box (NTC2).
By (very!) careful probing, I was able to confirm that the heaters were being switched off by the relays in the controller - not by the thermal cutouts on the heater assembly. So, they are under software control rather than some safety cut-out - which means that "garbage in, garbage out" must be the principle to consider...
The mains comes in and goes straight to the main controller. From there, wires go off to the heaters, motor, condensate lift pump, door sensor, etc. And there is a second control box. This is powered from the mains (post main power switch), but that's just about all I could establish at this point. It didn't seem important. A visual examination (plus a few in-situ tests) failed to raise alarm bells, so back together it went.
Using a plug-top power meter, I was able to confirm that the heater wasn't running. Well, not quite. Shortly after starting a program, the heaters do indeed come on. After a delay - perhaps 10 to 20 seconds - they go off, and don't come on again at all.
I took the back off and removed the heater assembly. There are 2 heaters - each one a kW - and there are 3 thermal breakers. There's one per heater, plus a third for the common return of both heaters - presumably a failsafe. And there's a 4th object that looks exactly like a thermal switch, but is actually an NTC thermistor that goes back to the main control box (NTC2).
By (very!) careful probing, I was able to confirm that the heaters were being switched off by the relays in the controller - not by the thermal cutouts on the heater assembly. So, they are under software control rather than some safety cut-out - which means that "garbage in, garbage out" must be the principle to consider...
