by
Fantom » Tue Mar 31, 2015 10:34 pm
Yes, after some research I found out that the temperature probe connected in the back was broken (pic2), then I assumed that was a platinum sensor cause I have seen some before, so I tried to measure the resistance and it showed 110ohm so PT100 it is.
There was no pt100 around so I plugged 2 parallel 215ohm resistors (107.5~20C) after restart the alarm persisted but oddly the oven fan turned on and the light in the room dimmed just a bit, the heater worked just for say.. 10 seconds.
Detector, Gas and Injector Temp. started to rise, and that was cool
Later was found that an oven temp sensor port was simply empty!! and there was a perfect place to fit it on top of the oven, where it was hanging perfectly in front of the oven fan, so plugged a resistor there too, hehe.
The alarm died and device became operational.
I assumed that back sensor was mistakenly connected by amateurish intervention in attempt to repair the thing. By the way, connector has general label like J5 or something, comparing to other that are labeled with additional "OVEN" or "DET"!
After some tracing and metering it was found out that circuit (pic1) was intended as trip wire in case temperature in oven flips out of range. It works using two comparators between 60 and 250 ohm. If we assume that it's PT100 than it would correspond to -100to+409C so I guess it's two sensors for oven as a precaution.
photo upload sites
Anyway, it's not like old GC's are usual around here so I intend to make it work )))
any help with manuals would be indispensable.