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Added thermocouples now needing some advice
IntrepidQ3
Over the weekend I installed HTC+TC4C in my Hottop B 2K.
I also installed thermocouples through the back panel to capture ET and BT. The TC's I used are from Omega, they are the 5 ready-made K-type 20 gauge Teflon.

I just took it for a test run with roastlogger. What I noticed is that my ET is 100F lower than my Hottop display. I also noticed that my BT has to be anything but wrong as it seems to cycle from 75F to 90F, this is even when my ET is around 223F and the HT display is at 323F.


I have checked connections more than twice and I do not see anything wrong here. It couldn't possibly the positioning of the TC's on the wall, as there is no way there is a small spot in the drum reading 90F while the rest is near 400F.

I would like to get this hashed out so I use my TC's as a guide and not my HT display. Currently if I go off the TC's and it reads 335F, as you all know the HT will auto eject since my ET is reading 100F cooler.

Could anyone provide an explanation or even suggest a possibility that I could explore as to what I am experiencing?

Thank you in advanced for any help
JackH
Make sure the polarity of the thermocouples are correct. Some have a red wire or band for plus but I have seen different colors used.

Also, try swapping the thermocouples to see if it is the probe or the channel in the TC4. If the problem moves to ET when you swap probes, then it may be the thermocouple. If it remains in the BT, then the channel in the TC4 may have a problem
---Jack

KKTO Roaster.
IntrepidQ3
Sounds logical and another weekend project.

I am disappoint and yet excited to breakdown the hottop again.
JimG
A simple but effective test is to temporarily substitute a short (1" to 2") loop of plain copper wire in place of the TC's. Make sure that the TC4C is providing a steady ambient (for the TC4C) temperature reading.

Unsteady readings are caused by bad connections, ground loops, or major electrical noise usually.

If the tips of your thermocouples are in contact with any metal in the Hottop, it can introduce ground loops and noise. (If the thermocouples are running really close to the motor, I suppose they could be picking up some noise, too, but I have not heard of this happening in an actual installation.)

In the class of "bad connections" is included any locations along the lengths of the TC's where a junction is created. Look for places where the teflon insulation on the TC's has been penetrated by sharp edges, etc.

Send a photo of your TC connections to the green terminals if you can. Even though you have checked them multiple times, the symptoms you describe are consistent with incorrect or intermittent connections at the terminals.

I test and calibrate every TC4C before shipping to try and eliminate hardware faults, so I always suspect the thermocouples first!

Jim
IntrepidQ3
Ok got into the HT a couple hours ago. Pulled the TC's out of the TC4C and reconnected with new. Seems much better. My ET is running 40F cooler than the HT display, which I think is OK. I have never gone to 395F with a roast using the HT display, so I do not need worry about the HT dumping my beans on me when it hits 435F.

Jim, you are correct it was the thermocouples and not your board. I didn't think it was, if anything I thinking I might have accidentally damaged it during install and didn't realize it.

Now since this issue is ameliorated. I have ran into another issue :C.

My HT keeps resetting itself about 3:30 min after I drop my beans. Oh boy! Did I hit something digging around the panels this time. Sorry I am slightly electronic illiterate, but was up for a new adventure and was willing to step out of my comfort zone for this exiting project.
IntrepidQ3
*exciting project
JimG
A reset of the Hottop can be triggered by a sudden step up in fan speed. If the fan is stopped, go to no more than 20% initially. Once running, fan speed can be increased in larger steps.

Jim
IntrepidQ3
Jim,

thank you again for the advice. I will give this a try.
IntrepidQ3
Advice looked wonderfully. Everything is working fine now. I am exciting to start recording roasts and furthering my knowledge of roasting!
IntrepidQ3
Issue continued possibly...

While inquiring about charge temps on HB I discovered that even though I have resolved my OP issue the readings I am getting with my thermocouples are still 'fishy', as a HB member put it.

When I run the HT without any beans the HT display is roughly 40F higher than my ET and BT. Even during roasting I notice this is the case. Does cause issues when I approach

I have been told I need to calibrate my thermocouples, which are Omega 5 ready-made K-type 20 gauge Teflon.

Is this necessary? If so, is there a means of calibrating via the TC4C so I do not need to remove them from the HT?
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