Problems - Thermocouple, Controller, or Configuration

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fixitguy
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Problems - Thermocouple, Controller, or Configuration

Post by fixitguy »

Following the manual as closely as possible, I still cannot make sense of the behavior of my JLD612 controller w/ ETC-CB-K1M K-type thermocouple. With the TC connected to terms 9 (+) and 10(-), the JLD612 "boots" OK and indicates "PASS" when I press "Set", and I am able to step through the configuration process with some conviction (although one parameter referred to in the manual as "Atdu" [and also as Atud"] seems to be represented as "Hy" by the controller). I have confirmed that it retains the values I intended by revisiting each parameter and observing that it still shows the value I just programmed.

My objective is to cycle a 1A heater element using the JLD612's internal relay @ J2, so I have selected "Outy" option "1" (which, if I understand the manual's meaning, causes AH2 and AL2 values to be ignored). I am able to configure a set temp (SV) and I think to configure AH1 and AL1 to values 5° and 3° respectively above SV. Yet when I "end" programming the configuration, the upper display rapidly cycles through seemingly random values, and the lower display erratically displays the set temp (alternately first blinking both digits ["37"], then just the LSD ["7"]. The J2 relay does not seem to close regardless of whether the probe is above, at, or below the SV.

When I disconnect the TC, the upper display shsows "EEEE" (as I would expect it to) and the lower display stabilizes, showing the SV without the erratic cycling I see when the TC is attached.

I realize that it is difficult to accurately measure the DC output of a thermocouple, as the test leads themselves influence the reported mV values, but I believe that a rough evaluation whether or not the TC is working can be performed using a Fluke multimeter. I observe an output of ~ -0.7mV @ 0°C. and ~ +1.6mV @ 58°C. Are these reasonable values for this thermocouple?

Is this particular type of thermocouple appropriate for use with this controller in a range of 35–70°C, or have I purchased the wrong TC? Could this TC be defective? Do the symptoms suggest a defective controller — or have I botched the configuration? Although I have not attempted to change the PID parameters, I have entered the programming mode to confirm that the default values are as indicated in the manual. I should add, that pressing and holding the ">" button to initiate auto-tuning as indicated in the manual causes the AT LED to light for about 1 second, with no apparent effect.
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