Tungsten.Chromium
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Magnetic Stirrer Repair
Hi all, I have a corning PC-351 hotplate stirrer combo I got off ebay a while back and the stirrer on it isnt working.
I've tried a few different stir bars but none want to move from the center. I'm thinking the motor is blown since the magnet is still there(sorta
flaky though).
Has anyone worked on one of these before? I opened up the back panel and it looks pretty straightforward, but I don't want to break anything. I
can't seem to find the unit's drawings or replacement parts anywhere online. I know this is an old model thats been discontinued for a while, but
would like to fix it rather then buy a new one. It's a solid piece of equipment you just don't see now days
Pic:
Prosit!
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chemrox
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If the stir bars don't go to the center maybe the interior magnet is gone. The stirring is caused by the magnetic interplay of the stir bar and the
magnet inside. It should be on top of the motor in the center. I've never opened one so this is guess work on my part but the principles are simple.
If you can't locate it use the thing as a hotplate and go back to ebay for a stirrer hotplate combo. I've gotten mine there and they were all under
$100US. Get a sand bucket too :^)
PS: have you checked the rheostats? Maybe one is shot. The wiring looks ok.
[Edited on 24-7-2015 by chemrox]
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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Dr.Bob
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You should be able to remove the top with the four screws and then see the magnet from the top.
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Tungsten.Chromium
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Sorry, I should have mentioned that this picture is of the bottom of the hotplate/stirrer. I was able to remove the top like Dr. Bob said and see the
magnet above the motor, will post pics of that later
Edit: When I turn the stir knob on, should you be able to tell? Right now the only thing it does is emit a faint little whine.
[Edited on 24-7-2015 by Tungsten.Chromium]
Prosit!
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Tungsten.Chromium
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Okay, here is a picture of the unit with the heating element removed and the magnet exposed.
The magnet itself is a little off center from the motor and only freely turns when the heating element is removed. (The magnet fits into a circle
groove on the bottom of the heating element) I'm not sure how the magnet is attached to the motor or how to adjust it, but my guess is that if I can
get it realigned then it'll work. Assuming the motor is not already burnt up from trying to force it to many times.
Prosit!
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aga
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The coils do not look burn out, and the whining noise means that it's trying to do something.
Magnet off-centre and sticking against the top plate sounds feasible.
Power it up with the top plate off and see if it turns.
(Put the bottom back on, wear gloves, rubber boots etc - all the usual safety caveats.)
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Tungsten.Chromium
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Yep, it was the magnet. It seems to be glued onto a platform that connects to the motor's arm and my guess is that after however long this thing has
been around, it started to come loose. I just pushed it back into alignment the best I could for now, but plan on later removing the magnetic,
cleaning the platform, and reattaching the two for a fresh seal.
Thank god it wasn't the motor, I can't find the model listed anywhere. Although I guess with motors if it has the same specs and fits, it should
work.
Prosit!
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aga
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Hot melt glue, SuperGlue, Epoxy, anything apart from drilling the magnet.
Well done on finding the fault !
Pretty soon it should be back in action, doing what it does best.
Heating, Stirring or both.
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