PT100 and JLD612 display correct temperature but no control

[hammer]

My sous vide controller (from http://www.instructables.com/id/Univers ... e-cooking/) displays the wrong temperature unless I wrap the braided sheathing on the sensor wires with about a dozen turns of insulated wire and connect one end of the insulated wire with one of the dark terminals on the sensor. Without this wire, the temperature apparently picks up noise and displays a wildly varying high temperature. If I connect the sheathing to the dark terminal, I get a negative wildly varying temperature reading. While hooked up and displaying those wild temperature numbers, I occasionally see the heater come on. The problem is, when the temperature is displayed correctly the heater never turns on, I tried turning the target value all the way up and all the way down and it never came on. My JLD612 has all the default settings except for PID values, as specified here: http://qandabe.com/2011/revised-sous-vi ... alibration . I've checked the sensor with a proper (low voltage) ohmmeter and it seems correct, at least at room temperature.

[richiem]

Just checking here -- "My JLD612 has all the default settings except for PID values."
1) Please be sure that Inty is set to P 00 or whatever your controller shows for Pt100 sensor, and that it is set for 0.1 degree resolution (mine says Pt10.0). Some 612's default to K thermocouple.
2) Please be sure that Outy is set to 2.
3) Please be sure that rd is set to 0
4) Please be sure that the SSR is connected to the 612 with the correct polarity: + to +, and - to -.
5) Please be sure that if you're setting temps in Fahrenheit, that CorF is set to 1 -- default is 0 = Celsius.
6) Some PID values will cause the controller to not converge on a setting, either turning off completely or turning on completely -- if it looks like you get temps that are right, try auto tuning.
7) Try stripping an inch of insulation from your insulated wire wrapped around the braid, and clamp or tightly tape the bare wire to the braid to make electrical contact, then connect the other end to terminal 10. Some people have reported that putting a 1uF film-type capacitor (voltage rating is not important) from terminal 8 to 9, and one from 8 to 10, helps with noise issues. Marco has some for sale. This may work better than the insulated wire shield.

Let us know if any of this helps.

[hammer]

richiem:

You are an excellent person, and a credit to your profession. Your manners are also impeccable. Thank you very much.

The most important thing to report is that I once I put the 1uf caps 8 to 9 and 8 to 10 on the 612, everything else started working as I expected. I bought the last two 1uf caps that they had at my friendly local Radio Shack for $1.59 each.

I now run with the braided sheathing "floating"; it is unconnected to anything.

Before I became capacitated, I corrected Outy and rd.

Thanks again richiem. I wish you riches and happiness, and that your decedents proliferate and cover the earth.

[richiem]

Glad to help.

[hammer]

I had some success with the controller, but mama's crock pot didn't have the watts (only 200) to move the water bath temperature very well. I made a deal on a scratch and dent Wolfgang Puck rice cooker (700W). The rice cooker can heat well, but the noise in my sensor is back. If I unplug the cooker, or remove the sensor from the water, the temperature reading stabilizes. When the probe is in the water, the temperature reading varies very fast about + or - 40 degrees. If I ground the braided sheathing to #10 on the JLD612, the temperature reading goes negative. What should I try next? Thanks.

[richiem]

Check the "scratch and dent" cooker for current leakage from the AC line to the pot (ground). One good way to do this is to plug it into a GFCI controlled outlet. If the GFCI trips, that's the problem that you are having -- AC leakage current upsetting the controller. But -- the cooker can have AC leakage to the cooker pot that doesn't trip the GFCI, i suppose, so be very careful to not electrocute yourself.

I think there's a short somewhere in the heater - thermostat - power system of the pot.

Can't really think of any other reason the trouble would come back in the way that you describe.