Probe Issue

josh1800 · Joined: 22 Nov 2014 Posts: 12

I'm having a bit of a sensor issue I'm hoping somebody can suggest where to start correcting it.

I am using a submersible RTD probe:

http://www.auberins.com/index.php?main_page=product_info&cPath=20_15&products_id=46

I brewed two days ago and my control panel worked fine. Today, I cannot get a temperature reading but instead get the "orAL" error indicating a short circuit. The PID reacts the same way regardless of whether the probe is or is not plugged in (shows a series of increasing temperatures followed by the error message).

I've checked all the solder point and wiring and everything looks good. Can anybody suggest what to do next?

Replace the probe?

Also, I went ahead and moistened my grains with 2% water by weight. Since I can't brew today are these garbage?

joe89 · Joined: 27 Feb 2015 Posts: 17 Location: Yorkshire, UK

I would suggest connecting the probe you suspect to be faulty into another PID this should tell you if the problem is with the PID or the RTD probe

josh1800 · Joined: 22 Nov 2014 Posts: 12

Unfortunately my system only uses a single PID. Any other ideas?

Yo_Pauly · Joined: 30 Nov 2014 Posts: 42 Location: New Richmond, WI

You should first check all RTD connections (crimp, solder, screw, etc.) If everything looks good you can use a multimeter to check the resistance. These are Pt100 three wire, correct? Disconnect the probe wiring ( I think there are two reds and a white or is it the other way around?) and measure the resistance between the white and either red (should be somewhere around 110 ohms at room temperature if I understand correctly. Then measure between the wires that are the same color (should be zero ohms.) I don't think the probe is shorted though or else you wouldn't see the temperature increasing before the PID displays the orAL message.