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Replacing thermal fuse with something that will reset

Discussion in 'Troubleshooting and Repair' started by mikemtnbikes, Jun 8, 2012.

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  1. mikemtnbikes

    mikemtnbikes

    5
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    Jun 8, 2012
    Hi,

    I have a blender (Cuisinart BFP-10CH) that uses thermal fuses (SE133a 66C (42C/107F temp cut off) to protect the motor from overheating. Instead of having to open the thing up and replace the fuses each time it over heats due to enthusiastic blending by myself or my wife, I'd prefer to implement a more permanent solution. Unfortunately, I'm not very knowledgeable about electronic and so I'd appreciate any help I can get.

    I've seen discussions about thermal switches but the closest thing I can find searching on Radio Shack's website are these thermostat discs that open once the disc reaches a particular temperature range. (e.g. NTE-DTO110 Disc Thermostat 0.500" Open on Rise 110 with the following specs: Temperature open: 113±5°F; 45±5°C, Temperature close: 77±5°F; 25±5°C).

    First, ignoring the fact that this is a bit higher temp than the fuse I'm replacing, I'm wondering if this will work for the task at hand.

    Second, I'm also wondering how the thing behaves between 77F and 113F. If it starts out cool does it stay closed until it reaches ~113F, open, and then not close again until it gets to ~77F?

    Any help would be greatly appreciated by me (and my wife whose getting impatient for her smoothies).

    Best,

    Mike
     
  2. shrtrnd

    shrtrnd

    3,734
    478
    Jan 15, 2010
    I've just got an opinion, somebody else may have a better one.
    The thermal fuse is to protect the motor (and prevent a fire). I wouldn't exceed the
    manufacturer's ratings. You'd probably only burn-out the motor (and have to replace the
    blender). But I've known a couple guys who bypassed features on their household
    applicances, then had their insurance company deny their claim for fires that resulted,
    because of what they had done.
    They do make resettable thermal fuses, just Google them for the types.
    If I were in your shoes, I'd go out and buy a more powerful blender, as the one you have
    was not designed to take whatever it is you're blending. The one you have could be
    used for less robust use on other dishes.
    Motors DO have physical limits. The thermal fuse is to protect it.
     
  3. mikemtnbikes

    mikemtnbikes

    5
    0
    Jun 8, 2012
    Opinions are fine, but....

    Darn. I was hoping for an answer to my questions not an opinion. But thanks for sharing. I think we will stick to the blender, it is pretty powerful already (600W) and it only happens every once and a while.

    I would greatly appreciate it if you could tell me if my understanding of the behavior of the thermostat discs described in the OP is correct or not.

    Best,

    Mike
     
  4. gorgon

    gorgon

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    24
    Jun 6, 2011
    Yes, that should be the function. It opens at 45 degC and close again at 25 degC. The problem may be to place it correct in the machine. You need to place it at the same location as the fuse, and with a good thermal connection.

    You should be aware that when the thermostat is closing, the motor will start again, if you don't turn the blender off when it stops. This may be a security hazard.

    If the blender stops on you due to overheating, you are either using it wrongly or it is something wrong with the motor, that makes it heat up. Clogged with dust or hands, and missing cooling comes to mind.

    I have no opinion :D

    TOK ;)
     
  5. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    Could be very dangerous to someone who doesn't know the machine is rigged to take off fingers.
     
  6. mikemtnbikes

    mikemtnbikes

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    0
    Jun 8, 2012
    Gorgon,

    Thanks for the helpful response. I was concerned about how to properly position the thermostat and have found some smaller ones that have similar specs that should work.

    Since everyone seems to be concerned about safety issues (there are some vivid imaginations out there) , I'll just mention that this problem, IMHO, stems from a poor design choices. The fuses are on the motor on the side at which air is taken in. As a result the fuses have been kept sufficiently cooled while the blender is being used. However, once it is turned off the heat from the motor ends up heating the fuses above their melting point, tripping them. So we've never had a fuse fail while using the blender, it's the next day when we go to use it it won't start.

    Thanks for all of your help.
     
  7. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    So then buy fuses that are rated for a higher temperature a few degrees might make all the difference. Looks like you might be the one with the wild imagination. :)
    The fuses aren't accomplishing much if they melt after the motor has turned off.

    Digikey is as good as any place to start. You can search by temperature.
     
    Last edited: Jun 14, 2012
  8. KJ6EAD

    KJ6EAD

    1,114
    157
    Aug 13, 2011
    The thermostat you found has hysteresis as you noticed. It's either on or off when the temperature is in the region between the two switch points. It isn't an appropriate solution for your blender. This is the type of resettable thermal switch I'd expect to find in that type of product. Once tripped, it has to have the power removed and cool to reset. You have to specify both a temperature and amperage (66°C and >5A).

    [​IMG]

    http://www.devale.com/bimetal-therm...lf-hold-snap-action-bimetallic-protector.html

    This is for later, after you've finished your fuse upgrade. :rolleyes:

    [​IMG]

    http://www.blendtec.com/products/total_blender_classic_fourside
     
    Last edited: Jun 14, 2012
  9. mikemtnbikes

    mikemtnbikes

    5
    0
    Jun 8, 2012
    Putting in a fuse with a higher rating was what I did the second time (the first time it was still under warranty so I sent it back). Now that I'm at the third time in as many years and I figure I might as well fix it for good.

    Thanks for the input.
     
  10. mikemtnbikes

    mikemtnbikes

    5
    0
    Jun 8, 2012
    KJ6EAD,

    Thanks for the info on the thermostat and link. I will admit that's quite a blender!
    Best,

    Mike
     
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