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Old 01-19-15, 03:46 PM   #1
AC_Hacker
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Default Cooktek MC2500 Induction Cooker Repair

I bought a "well used" Cooktek MC2500 Induction Cooker from ebay, because I wanted an induction cooker with precise temperature control.

When I got the cooker, I did some closely monitored temperature testing, and the results were very disappointing. But since I had waited so long, return was not an option. So it lived in my basement for a couple of years.

One day I was sweeping the basement floor, and I had stood the cooker on edge while I was cleaning under and it, and I knocked the cooker and it fell on the glass, and totally shattered the glass. Huge bummer.

I should have taken a photo of it broken, but it made me so sick to look at it, that I just didn't.


(The first 4 digits of serial number (5020) at the bottom of the photo tells the series. Mine is from about the year 2003)

I called Cooktek about replacement parts, and discovered that they do not support product that is more than 7 years old. End of story.

I also learned that they do not disclose any schematics or any other repair information, though they will sell parts for current product. There is no place that a Cooktek can be repaired except Cooktek Repair. Hmmmmm.....

They didn't have any glass and they were very vague about where they got it or what kind it was. Though they did say "ceramic glass" and also "not tempered".

I measured the shattered glass I had (13 7/16" square) and I measured the thickness (0.155"). I noticed that it was black, textured on the back and smooth on the front.

So I did 'the google' for about a half hour, looking for fireplace glass, and I finally located a place that had what I wanted and just about the same dreadful expensiveness as all the rest ($82).

The glass they have is called "Neoceram" and they had it in a thickness of 5/32", which turned out to be exactly the right thickness. An lucky for me, they were only 8 miles away.

When I picked it up, I noticed that it was cut to perfect dimensions, and was textured on the back exactly the same as the Cooktek glass, and when held up to the light, the opacity was no different from original glass. So, as far as I can tell, I found the identical replacement glass. Thank you Cooktek, for all your help.

So, I set about removing the old glass, and it was glued in with some extraordinarily tough silicone-type glue, and it was a bitch to get out, but by applying considerable will and a sharp paring knife, it all came out.



Word of caution here, if you ever have to do what I did, this untempered ceramic glass produces an unusual amount of very tiny, very sharp slivers, that is way beyond what you might expect from regular glass. So be prepared with a plastic cover over your work surface to catch all the tiny debris. No joke.



The innards were interesting! The cooking coil is nice and large, at 8+ inches, and appears to actually be two concentric coils, presumably for automatic pot-size detection and adjustment.

I finally found a suitable High-temperature Silicone, and was preparing to re-attach the class, and I noticed that the Cooktek employs a fiberglass mat that is in contact with the glass, but not attached to the glass. There is a 2" diameter hole in the middle of the mat for temperature probe, that contacts the glass. I noticed that the hole was centered, but the temperature probe was off-center, and could easily have been missing full contact with the top glass. I got some tiny scissors and cut the hole larger to assure full temperature probe contact.

I also noticed that the temperature probe (probably a thermocouple) was encrusted in old thermal compound, so I gently picked away the old compound.

I also saw that the probe rested on top of a small disk of glass fiber, that was disintegrating in my hands as I examined it. So, I went to a local pottery-maker supply house and got a small amount of refectory blanket that was just slightly thicker than I required. I also got some fiber gasket material and cut thin holes for the probe leads.

I ended up with (bottom to top) the refractory blanket, then the fiber gasket, then the temperature probe lying flat on the gasket material. I dabbed on some of the really good silver-particle thermal paste that is intended for CPU-to-HeatSink mounting.

I did a dry run with thermal paste to assure that the sensor was in contact with the glass. Everything looked centered and good.

So, I put the glass in place, and then I put a pot of water on top of the glass to hold everything in place, and went to work with the Hi-Temp Silicone, filling all the gaps and smoothing the edges.

I let it sit for 24 hours.

I put power to the unit and turned it on. Everything seemed to work OK.

Then I measured the temperatures of water that I heated with the unit, and to my delighted astonishment, they were within 2 degrees of indicated temperatures!

So, the accident of the broken glass revealed the defect of the sensor placement.


Now everything is as I had wished it to be.

I call this a success.

-AC

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Last edited by AC_Hacker; 01-19-15 at 03:51 PM..
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Old 01-19-15, 03:52 PM   #2
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Good job. I am glad it worked out.
Will this one simmer?

I looked it up that one looks like a great little cooker.

Last edited by pinballlooking; 01-19-15 at 03:55 PM..
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Old 01-19-15, 06:30 PM   #3
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Quote:
Originally Posted by pinballlooking View Post
Good job. I am glad it worked out.
Will this one simmer?

I looked it up that one looks like a great little cooker.
Yes, it simmers.

It's temperature range is from 80F to 500F, and it has 27 steps, but they are not equally divided. Some are in 5 degree increments, some are 10 degree, and some are bigger. I'll have to work with it, to figure out the logic of the settings.

But yes, it does have a simmer setting, and what is more interesting to me is that it has a setting at 200F which is 'sub-simmer', that gives you almost as much heat as simmer, but for the most part, doesn't need stirring. I cook a lot of beans, and this is just great for that.

-AC

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