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Author: Subject: Replacing Stirrer Motor Corning PC-320
STFA20
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sad.gif posted on 9-1-2020 at 13:24
Replacing Stirrer Motor Corning PC-320


I've had this workhorse for 15 years and I'm not ready to give up on it. After replacing the triac and the pulse generating IC, I realized that it was the stator windings themselves that had fried.

I've got the magnet and fins sitting in pentrating oil, trying to free the piece that is keyed to the motor shaft, but I've torn apart almost all my appliances looking for a shaded pole motor with a matching shaft diameter.

Can someone assist in finding a suitable replacement motor? I'm sure only a few dimensions and specs are used to describe these things to manufacturers but I don't know enough about this to know how custom this motor really is... certainly not worth the price from Corning.

Thanks for your help, brothers and sisters!



It's a brilliantly simple PCB, and in my mind, simplicity is elegance.
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Heptylene
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[*] posted on 9-1-2020 at 15:34


Have you considered rewinding it yourself? You can buy enameled copper wire of any diameter online. If you can count the number of turns you can make an identical coil.

You could also buy an identical broken hotplate on ebay, and scavenge the part you need from it. This https://www.ebay.com/itm/Corning-PC-320-Laboratory-Ceramic-Stirrer-Hot-Plate-Portion-Does-Not-Function/123736395689?hash=item1ccf438fa9:g:OwIAAOSwj39c tLEQ for example lists the heater as non-functional but the stirrer works.

[Edited on 9-1-2020 by Heptylene]
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STFA20
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[*] posted on 10-1-2020 at 05:11


Now why didn't that come up when I searched for it? That's exactly the thing i've been after! Still a bit dear, though, for a shaded pole motor (SPM). I mean, is there something about the slip configuration that makes stirrer motors special in some way? something that makes them less prone to decoupling?

I had considered rewinding, but the windings are put in as a press fit in the laminated stator stack and I cant remove the windings without either cutting the stator stack and replacing it with another similar winding from same stack thickness SPM or threading each loop of wire through the gap in the stack by hand, which seems like a massive PITA and likely to be a crap result.

With respect to to first option, has anyone tried welding the stacked stator plates together? It would be the only way to reattach a new winding (without the doing the threading thing), and I suspect that fusing the plates together will interfere with the induced field.

Having met a lot of SPM's lately, I can't see enough difference between either the build quility or the motor itself to justify the price of stirrer motors, and was hoping we could figure out the language for getting a drop-in replacement for stirrer SPM's... possibly put a repair database together, who knows.

Most of the variation between SPMs is in shaft and rotor diameter, with build quality showing up in shaft run-out. The stack thickness doesn't vary significantly, neither do the mounting holes. I want to believe there is a $5 SPM out there that shares the same shaft/rotor diameter as the stirrer, with a stack close enough that the magnet isn't scraping the bottom of the plate.

Thanks for the link, btw!
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