Hi,

I have a Partlow MIC 6000 that I can't get to read a K-type thermocouple correctly. The jumpers on the boards are set correctly, the inps is set to 3 (K-type 'F') and all the other parameters are set to factory settings. I've tried other thermocouples which read correctly on other controllers but no luck. I've done the first calibration but the others need test equipment I don't have. Any quick ideas?

 

The 10th edition manual is here:
http://www.jacksonoven.com/import/default/downloads/MIC6000manual.pdf

If the 10th edition was published in 1993, your model is probably celebrating its 20th birthday.

Several things could be happening

- the front end took a hit and is no longer functional

- it could be functional but so far out of calibration that the readings are useless, if from nothing else but the 'cal' buttons which activates the calibration function without a source calibrator connected.

- cold junction is way out of cal, or cold junction is disabled

- jumpers on other boards affect to the thermocouple input

- electrolytic caps are flaky

If the input is bad, the diagnostics should have an error code (SnSr, pg 58). You didn't mention an error code.

So it might be out of calibration. It appears that the controller has a means of resetting the calibration constants back to factory settings.

Check out the manual for the section called Cal 2:
CAL 2 QUICK CALIBRATION
This routine will allow the operator to execute a rough calibration on their unit via the keypad with no other equipment or disturbance to established wiring.

It appears that there are multiple boards with jumpers that select thermocouple (with cold junction) or mV (without cold junction). It isn't clear which board(s) you have, but you need to make sure whatever jumpers are there are in the correct locations.

Electrolytic capacitors age and die, but that normally affects the uP functions. There are likely a half dozen in a 20 year old single loop controller.

 

Thanks David,

I found a place here in Boulder that will look at it but not without a schematic. Any ideas where I might find one? partlow.com was no help...

 

There probably is no publicly available schematic. Schematics generally disappeared with adoption of microprocessors 25 years ago.

If it were me, I'd buy a replacement controller. Most 16th DIN single loop controllers today can do what the 1/4 DIN MIC6000 did back then at a fraction of the cost (unless the control output is driving a slidewire feedback actuator).

Did you ever see the movie "The Money Pit" with Tom Hanks and Shelley Long? Legacy electronics can be just like an old house - a money pit.

 

ah you engineer types are so practical! i fixed my shattered iPhone screen by myself and developed delusions of grandeur that this was worth saving. Time to move on.

Thanks for your help David

 

Rob,

Before you give up on it, look up that CAL 2 QUICK CALIBRATION procedure in the manual and give it a try.

It's a one minute procedure of button pushing that might bring it back enough to be useable.

I'd just be reluctant to throw good money after bad in an attempt to 'repair' it.

David

 

David,

Thanks for your help!

I got it working/reading correctly. After trying the CAL2 a number of times and not getting the display to blank then come back. I decided to start over and found a jumper i'd overlooked that did the trick! I had just picked up new caps and had the iron all warmed up.

Thank you for the encouragement
Rob