Help - PID issues

[sojerguy]

I may have sold a defective item here, and as I'd prefer to keep a good reputation I Want To Find out what the issue is and get it taken care of.

Background: I bought a PID here about 2-3 years back (moderators anyway of going back that far?), never used it and in December sold it here on this forum. Pics shown here for IDing it.

Its not working correctly and I've cut and pasted the 3 emails I've received from the buyer. They're below:

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1) Got it set up and it says its 70 something degree s and auto calibrate won't adjust it. It’s about 50 deg. And it brought my pot up to 900!
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2) Out on the road again. Sorry. Remember who you bought it from? Most likely the pid itself is bad. Both The thermocouple read the same and they are pretty bullet proof. The wiring looks correct.
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3) Just an update, I ordered a new mypin PID box, and a thermocouple, and they should be in in a couple of days.

I'll try the thermocouple first to see if there was a short in the original connection, and if not I'll swap wires to the replacement PID.

But if you remember who you got this from, they might have some better insight.
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So .... ideas on what it likely to be wrong? Suggested fixes for it (please no boat anchor jokes ... its not heavy enough).

Thanks

[HATCH]

This is the wrong section for discussion.
I will move the thread after I answer.
Auto calibrate will not change the temp that it is reading. Auto calibrate is for the PID to learn the heating characteristics of the device it is hooked too.
And yes, if you hit it you may see a high temp as it learns.

From the picture I see a potential problem.
On the first picture.
See the TC plug?
Look at the wires.
They don’t look like the correct wires
Thermocouples have special wire.
If I am correct, changing the PID will not fix the problem.

If you give me their USPS address I will be more then happy to send out some of the correct wire so they can change it out. I am sure those are K type thermocouples.

Also i am also more then willing to physically check the unit out at no charge besides shipping to me. I will even pick up return shipping.

[HATCH]

Just thought of something quicker

Open the unit up.
On the PID will be the wires coming from the extension (think is green and blue)
Remove them.
Now grab one of the TC.
The yellow plug has two screws.
Open it up and remove the wires from it.
Hook those wires up directly to where the extension wires where hooked up.
Power the unit up and see what it reads.
For fun you can get a glass of ice water with a little salt in it and that should be at 32f or close to it.

[HATCH]

The one of the TC wires should be red. That is +.
Make sure that is hooked up correctly.
If it’s hooked up backwards the temp will go down when you grab the probe with your hand

[sojerguy]

Hatch,

Thank you. Will pass on the info to the buyer.

[Master Samwise]

Guys, thanks, it is a great help post. Especially since I am the customer in question.

I've tried about half of the suggestions and had jumped on ordering the replacement parts knowing that I can return them if needed. I've done a fair amount of troubleshooting for industrial type controls so I am interested to sort this problem out, since its for me.
I had opened it up last night and noticed that the there was no grommet for the TC wire piercing the case, just loosely wrapped electrical tape to protect it. So there may be a shorting issue, even if it isn't the right kind of wire, which I hadn't considered.

Testing in ice water was done, but made no difference, either.

I had also swapped the polarity of the TC connections on the PID, with only minor change in displayed temp. but they were still going through the extension wires which are incorrect or damaged, or both. Directly connecting the TC to the PID didn't even occur to me for some reason.

~Samwise~

[HATCH]

There could be a couple issues.
Incorrect extension wire as mentioned
Incorrect TC setting in PID

Imagine a curve with a number 10 in the middle of the curve.
A K type may see that #10 as 500f
A J type may see that #10 as 400f
If your PID is configured for a J type instead of a K type the ln that could explain your problem as well.

I would first hook the TC directly to the PID.
If you haven’t touched the probe it should read ambient temperature.
What I do is if it reads ambient then I grab it with my hand to watch the temp go up.
If it does go up then everything is whited correctly and the factory built the TC to specs.
I have yet to have a TC be wrong and I have tested all the ones I have sold with ice water.
1 degree difference is acceptable.

Keep in mind with huge quick changes in temperature the TC will take some time to read the exact temp.
Ice water from ambient can take ten mins to read on the money.

Also before you write that PID off, most PIDs are configured for K type so putting a brand new one may solve your problem but it doesn’t mean the old one was broken, could just be configured incorrectly.

Charles

[Master Samwise]

you know, I find it interesting that when I busted out my multimeter with a K-type connection on it, I was getting the same 60 something degree reading from the two supplied TC in this kit, both in ice water and in my hand. So I opened both of the connector ends to get the wires for connecting to the PID, and I find the TC wires wrapped around their screws in kind of a heart shape and then over lapping the bare wire ends like how you might see a pretzel. Looked like an obvious short to me, so I isolate the wires for their side and try connecting them again.
Low and behold it's reading ice water at 34 degrees and warming up quick when I put it in my hand.

Not one, but both TC had crossed wires in their k connectors.
I checked the continuity of the whip connection coming from the box and all seemed righteous, good conti and no obvious ground fault. So I hooked each TC up and they both gave good readings.

I'm glad I've had the help sorting out this problem and really got to learn more about troubleshooting a new control. its one thing to have a system set up and have its information reporting back to PLC, expecting it to be regularly working. It's another thing to get systems to fail and have to hunt down issues.
Now that I have a duplicate PID and TC, in box ready to install, I wonder if I shouldn't try to set up a second system for my other pot. I have a 8lb and a 20. Might only be another 10 to 20$ in parts.

[Mr_Sheesh]

Shorting them there would explain much! Good detective work

[HATCH]

I would still change the extension wire to the correct wire.

The original maker must of never tested the unit out.
I check every one of mine out that I make and sell.

Glad it’s fixed

[Hootmix]

Those sneaky little TC's...they were the cause of all my PID problems ,,found the same help HERE.

coffee's ready,,,,Hoomix.