Erratic temperature fluctuations when TC bumped/moved

[jayhkr]

So I finally got the auto tune feature figured out now here's a new one. The unit was on and warming up when I bumped the spring part of the TC that is between the probe and wire. I noticed the temperature reading going all haywire. It didn't settle remotely close to where it was before. All connections appear to be tight. Could it be the Chinese TC? I also noticed this when I move the entire unit that everything is housed in. What could it be. I've attached a quick youtube video of it to show what I'm talking about.
http://youtu.be/gwk9MvaTVdQ

[shaune509]

My first spot to look is a frayed tc wire or junction. The wire inside that spring strain relief on the tc is covering the bad spot and when you move it the wires are shorting together further from the true tip and changing the reading.
Shaune509

[jayhkr]

And I assume there's no fix for that?

[shaune509]

Replace only/best option for bad tc's. Sorry.
Our company made our tc's for a limit sensor system, ours did not need tobe for precision temps just limit rangeing to control. We twisted the wire ends 3/4" together [type k], inserted into 1/4" od 304ss tube to the end crimped tube and then welded tip. then installed std AMP 2 pin connector for plug to pc board. The pc board had the adjustment for setting the range with the function tester at assembly, only test we did to the tc was to plug into an Omega readout and hold tip between fingers and make surew polarity was right by showing temp rise from ambiant.
Shaune509

[jayhkr]

C-rap.....I don't get it. I didn't touch ANYTHING on it until I bumped it, and it was working really good this morning. I can't see that me bumping it caused it to short out. Looks like I need to order a new one......probably go through Auber's this time and not a Chinese made *********

Thanks.

[el34]

Do you have a way to check continuity? You should read close to a dead short across the two TC terminals. If wiggling it affects the continuity test, try limiting the wiggling to small areas like at the spring, along the cable, etc. Another thought is to check for ANY continuity from either terminal to the stainless probe- if the TC wires pick up a tiny bit of AC hum from the pot it could throw the controller into stupid.

Can you take the probe out of the pot and check its behavior just in air?

Prolly just get another TC.

[jayhkr]

Yep, does the same in the air. I had it really dialed in when I did the water test. My digital thermometer and the TC measured within a few degrees. Not sure how to test for continuity, all I have is a multimeter (electricity is not my strong suit at ALL). So frustrating, but that's what I get for buying cheap I guess.

[dikman]

Your multimeter should be able to read ohms (for measuring resistance). Select the lowest reading (might be 200 ohms?) and when you measure across the probe terminals you should get a very low reading (as el34 said). If you don't get a reading then it's open circuit.

As for where the probe is made, don't be so sure that the Auber's one doesn't come from the same source. I built two complete systems (I have two pots) which effectively gives me a spare. Considering the low cost of the probes out of Hong Kong, I'm about to order another one (or two?) to keep as spares.

[jayhkr]

As soon as I get some coffee in me and get fully awake and going I'll head downstairs and try to get a read. Good to know about the source ordering, sounds like I might as well do the same and order a few more from Hong Kong. Heck, last time it only took 8 days to get here from over seas.

[Beagle333]

I bought a 6 pack of em from Ebay to have some for my applications as well as a few spares. I knew that even if they worked properly, it won't be long before I snag it on something while moving it, or crimp it badly or somehow damage the thing.

[jayhkr]

Yeah, I ordered 2 of them from ebay along with the coupler pieces so I can disconnect it from the unit when I want. Spent less than $12 for everything, we'll just see how long it takes to get here.

Also curious, how do you get your PID to mount securely to whatever is the container for everything? Right now mine is literally just plopped in the square hole I cut out and it flops over. I didn't want to use the plastic clips that you screw in if at all possible. I see a lot of peoples controller unit and I don't see screws above and below the PID so I'm wondering how everyone secured theirs. Thinking of making a new container for my stuff soon too. Probably 1/4" steel sheets cut and welded to size. I haven't welded in a few years and this would be a good, simple project for me to dust the cob webs off!

[Beagle333]

I don't know how to mount a MyPin. Mine is an Auberins and it has springy plastic clips on the side that snap out after you push it through the proper sized hole.

[dikman]

Both of mine (an XMT and a REX-C100) have plastic clips that slide over the back and snap in place. They push against the back of the mounting panel, no screws. From what I've seen, looking at various PIDs on ebay, most seem to use this type of mounting.

[Mike W1]

I don't know how to mount a MyPin. Mine is an Auberins and it has springy plastic clips on the side that snap out after you push it through the proper sized hole.

I almost hate to admit it but I had a slight problem with my clips until it finally dawned on me. Take the clip off the unit, slide the PID into the hole and then put the clip back on from the inside of the box. Worked fine when I did it right.

[jayhkr]

Yeah, mine don't seem to hold that tight without using screws. I'll fidget with it before I build the new housing unit for it. Thanks guys. Glad I'm getting all this worked out before I actually start casting boolits. Just been casting fishing sinkers (home business) right now to get the hang of the temperature unit. My plan is to start casting the no-groove 9mm Mi-Hek boolits this winter and coat them in either harbor freight PC or go all out and buy the Hi-Tek coatings. Rather practice now and learn!

[finishman2000]

my clips don't hold well so I ran a bead of hot glue around it on the inside. secure now.

[jayhkr]

I figured mine out. I had them on backwards as I thought the round part went forward. Seriously haven't felt more dumb during this project. Lucky I have a great group of people here for help!

[el34]

Those clips have a 'spring' built into them that helps keep the controller snug after you apply a little forward pressure on them from inside the box.

[dikman]

Jay, no need to feel dumb as there is an acute lack of information that seems to come with these things! Nothing wrong with asking, it's far better than breaking something. By asking it stimulates the brain cells into thinking about a problem. There is certainly lots of useful info on this site .

[monadnock#5]

I work with TC's every day on the job but am not the one to reorder or replace them, so knowledgeable, but no expert.

TC's go bad from time to time, and when they do there is no fix, just replace them. Keeping 3 or 4 in ready inventory is an excellent idea. The K type that we use are good and bad. Good, in that they're relatively inexpensive to replace. Bad, in that quality from the manufacturer is not a high priority, and sooner or later you WILL install an out of the box, brand new bad TC.

In an industrial application, TC's are replaced on a schedule (if they last that long). We want our money's worth, so we use them up. Just know that the number of uses will not be the same for each TC.