STC1000 Calibration

[SergeMarx]

hey guys,

I use an STC1000 for controlling the mash in my electric urn, but with a string of brews recently failing to attenuate, after ramping up the yeast and oxygen to no avail, I wondered if the calibration was out. I'd checked it last maybe 18mths ago and brought it in line (was 4c) out, but now it seems it's a whopping 15c out. So, attenuation probably explained, but how to fix? You can only correct the readings up to 10C. I've purchased a new sensor lead on ebay today - so that may help, but thought i'd ask if anyone has had similar issues and how they were solved?

Thanks

 

[damoninja]

While you're at it may as well order a whole new unit from the evil bay, they don't cost much and it's not a terrible thing to have a spare of.

The probe may well do the trick.

 

[kaiserben]

now it seems it's a whopping 15c out.

Woah!

I should probably check mine more often then.

With yours, I'm almost certain it'll be the sensor and replacing it will solve your problem.

 

[SergeMarx]

In the end I had three different thermometers in boiling water and they all showed different readings. TRUST NO-ONE!

 

[Crakkers]

TRUST NO-ONE!

Or get a Thermapen.

 

[Rocker1986]

I don't use an STC for mash temps but I do calibrate it once every month or two to make sure the fermentations are where they should be. It's usually fine but sometimes it creeps a degree or two. Probably a good idea to do it regularly especially with mash temp measuring. I've never had one 15C out though!

 

[Zorco]

Exact same problem and same delta!! Last week in fact.

Was for my keezer.... froze my beer at the reported 2degC.

Calibrated it against my PID

Wound it to -10 in the adjustment and have the PID supervising. Now it is 3 degC on the STC and -0.2 on the Omron.


Not good enough for me. I'm thinking of going down the warranty Avenue. I bought a spare so will try that first.

Always have a spare STC-1000

I'll try and find who I bought it from. Some eBay crowd

 

[MHB]

Have a look at where the sensor wires go into the STC, a bit of corrosion can cause all sorts of corrupt data.
I usually crimp on a straight connector so the junction isn't wire to screw terminal, rather a metal to metal connection.
Mark

 

[SergeMarx]

A mate just bought a new STC1000 so i grabbed his sensor lead to see. Problem solved - now just a +1C calibration required. I'm sure sure there's a lesson in all this somewhere...

 

[Zorco]

That makes sense. I'll try the other sensor lead I have and see if it happens with that one as well. Might not though as they were bought at the same exact time and could be a batch problem.

I liked MHB's idea above. But i've also found to the opposite to be true. A crimp on an especially fine wire can be a source of wildly varying impedance, especially when PT100s and other RTDs move micro-milliamps. But if the gauge of the wire is thick enough then a crimp should be of no electrical consequence and benefit the reliability of the junctions.

It's always metal on metal in electrical / controls / signals

https://www.youtube.com/watch?v=jDC2e6i6Quw