STC-1000 Gone wrong

[Dave1970]

I was messing around in the garage, attempting to drill through a tank connector. The best suited drill I have for the job is an ancient low speed drill that belonged to my Grandad - probably not been used since he died in the mid 1970's. So I plug it in and give it a go and not entirely surprisingly it trips the garage electrics immediately - no great surprise there.
As I wander out I remember that my lager has had 4 or 5 days at 18 C to get the yeast to clear up and it's time to crash chill. The display on the STC reads 25.4 C - wtf? the 'cool' light was flashing. My first thought was that my fridge had bust, but when I unplugged the fridge from the controller and plugged it straight in it worked and the lager is now happily chilling.
Bringing the STC in to test it seems to be reading between 25.2 and 25.4 regardless, putting the sensor in ice water doesn't make any difference - has anyone seen anything like this before? On the plus side my lager probably wasn't that hot but what about the STC? Is it knackered? Could the garage electrics tripping have damaged it somehow?

 

[Dave1970]

38 views and no answer - thanks for looking, I guess no-one knows the answer to this one.

If it's the probe gone bad is there any way I can use a multimeter to test this? Can anyone tell me what the resistance is on a working probe and whether it varies with temperature?
If I do need a replacement probe would this be OK?

 

[hairybiker]

It's an NTC probe. Thats about all I know of it.

 

[evanvine]

Sounds like your probe is knackered!
Can you borrow another to test with?

 

[winelight]

The resistance should go down as the temperature goes up (NTC = negative temperature coefficient).

The chart at this link is I believe the correct one for the probe for the STC-1000 (I'm not suggesting that this is a good seller, merely that they have very kindly provided us with the chart for reference).

You will probably have to recalibrate anyway if you change the probe. But check resistance first in case it's the STC-1000 itself and the probe is in fact fine.

 

[Dave1970]

Thanks Winelight...at least I can test it now :thumb:

 

[winelight]

Good luck and let us know how you get on.

 

[joe1002]

I wouldn't have thought the electrics tripping would mess with your STC. I frequently test trip my RCD's in my brew house and more often than not the STC's are on. Not had any problems with them to date.

 

[Dave1970]

Looks like the sensor might be OK...

I get a resistance of 20.8 in water at just under 10 C, in hot water at 55C it's down to 3.8, not far off what the chart says, looks like the unit has gone **** up

 

[Good Ed]

mine's just gone bonkers, had a mild chilled to 12C when set at 19C. I've now got a new one but will just swap over the probe first to see if that does it, otherwise I'll replace the unit.

 

[winelight]

looks like the unit has gone **** up

Sorry to hear that. Any news yet? Have you replaced it?

 

[Dave1970]

Yes, new unit came yesterday, tried the old one with the new probe just in case, no difference so replaced the whole unit - all working now.

 

[winelight]

Glad it's working now.