Coffee Whisker Suddenly Stopped Working

[Boris_yo]

Hello technicians and electricians 

I assume  many here know what type of gadget I am referring to here? It is a coffee whisker operating on 2 AA batteries to make coffee with foam and save you time whisking with spoon. It is also more effective because it dissolves coffee and sugar better than it is stirring with spoon.

So after using it for half a year, mine suddenly became very slow at rotating. Replaced batteries but nothing changed. After a few days the motor stopped working at all and became somewhat hot so I decided to disassemble.

I have attached picture on the bottom for you to see and you can tell from picture that some parts of wires have melted. What I noticed is that as soon as I connect cable 2 to contact 2 (middle one) with rocker pressed on, the wire gets hot and smoke starts to show. Same consition can be achieved when connecting cable 2 to left contact of motor (I didn't mark that spot on picture).

What do you think is the problem? Is motor shortening or dead? Fixing things is my passion, therefore I rather fix than buy new.

[6502nop]

Brushes probably shorted to case (broken) or shorting adjacent windings (worn to stubs).

The nice thing is that it looks like a bog-standard higher torque Mabuchi style motor, and is easy to tear apart and examine. Mabuchi themselves offer some very extensive interactive guides on how to do this:

http://www.mabuchi-motor.co.jp/en_US/technic/t_0104.html

Just pull any gear or spindle off the output shaft, mark and unsolder the wires, pull up the small metal case tabs holding the rear plastic backing plate, and pull apart.

If you're lucky, it may be something got dislodged. Just reseat it, lube the bearings while you're there, and slide back together. If you're not lucky, something broke or wore out to the point of needing replacement. Still, one of these should only run between $5-10 (US), so it's not a big deal to replace.

nop

[Boris_yo]

If you're not lucky, something broke or wore out to the point of needing replacement. Still, one of these should only run between $5-10 (US), so it's not a big deal to replace.

nop

Thanks for your reply and reference guide. If I were to buy motor, I would just buy another whisker that costs almost $4. Or if too curious I would get motor though just to have learning experience.

[Mechatrommer]

What do you think is the problem? Is motor shortening or dead?

i think santa is inside.

Fixing things is my passion, therefore I rather fix than buy new.

so dont open a thread, open a motor. its not rocket science.

since you asked. from my experience dismantling cheap motors like this... from the picture alone, i'm "speculating" either you need a new motor, or if its not too expensive, you need a new whisker. i hope i can save your time with this statement

[Fraser]

A key question with a device like this is .... can the motor spindle be turned easily with your fingers ? A motor that slows down and then stops with high current draw is often the victim if a seized oilite bearing. As the unit is used with fluid, the front bearing may have suffered fluid contamination and caused the failure.

[SeanB]

Normally the motor "brush" dies with time. I use the term brush very loosely, as the brush assembly is just a phosphor bronze leaf running on the commutator. I have transplanted motors into these before, or you can use a back plate from another if you need a long output shaft and have none in the scrap bin. You find the brush leaves wear out and then short together, often you have a groove worn in the 3 commutator plates as well from it. If you have it apart a drop of oil on the front and back bushes will do wonders for noise, just use a drop of engine oil, nothing lighter. Lighter oils evaporate, and the thicker engine oil reduces wear as it forms  a thicker hydrodynamic film when the shaft is rotating, as it often has a very large clearance either from wear of from manufacture.

[Boris_yo]

I opened motor cover and saw that its base is dirty which seems is the result of sparks. It feels as if current tried to spin motor but motor was stubborn. I tried to spin motor and a little resistance can be felt but I cannot tell 100% it is the motor that resists because when whisker was new I don't remember spinning it manually. What is strange is that after short while when I power on device, the motor spins for 1 second and then ceases to spin. If I try to power on again, then wire becomes very hot. After I wait again and power on, motor can spin again although it is not always so.

Attached are pictures below and by the way, I cannot remove whisker's bar to reach bearings because there is plastic on the bar that prevents pushing bar to the end which would reveal insides of motor.

Also I have penetration oil which I use to release stubborn parts. Would it be okay as lubricant? I also have cooking and olive oil and wonder if these evaporate.

[marshallh]

Generally those motors are supposed to have a 0.47uF snubber cap across the terminals, it helps prevent the arcing of the brush dust.

Buy a new whisker and solder in a cap, won't hurt.

[Fraser]

Penetrating oil is only for freeing purposed and not much use as a lubricant. WD40 claims to be both so you could try that.

Cooking related oils are totally unsuitable.

My recommendation is car oil (new of course) or 3in1 oil.

[SeanB]

Needs new brushes for sure, and then it will probably work. Car motor oil is the right lube for the front and rear bushes.

[G7PSK]

Never use cooking oil for lubrication, not only does it dry up and go sticky it also contains acids which will corrode.

[mrflibble]

Forget about repairing that junk. Get yourself an ALL-DROID Stirmaster!



Two weeks skiing! 

[IanB]

My recommendation is car oil (new of course) or 3in1 oil.

Although there is probably a low risk of contamination, car oil is not really designed for food use. It contains additives that are not safe for human consumption. I would suggest using food grade mineral oil from a pharmacy instead.

[Fraser]

Good point  I don't normally deal with food related products.

When all is said and done, these things are designed to be thrown away once the brushes expire. It may be a bit of fun for the OP but I would never spend time repairing one of these very cheaply built motors. I did rebuild a special (read very expensive) brushless motor in a Sony C5 Betamax video recorder many moons ago....but that's another story 

[eKretz]

If he just wants to repair it for the heck of it he could always just put in a new motor.

[KJDS]

WTF is wrong with a teaspoon?

[G7PSK]

I think that this is the second time I have seen how to repair a coffee whisk on this forum in a year, the obvious answer is to get equipment that will last - something like this will last a lifetime.

[amyk]

2 AA batteries are enough to cause some not-so-thin wires to smoke? Those don't look like ordinary batteries to me...

[Mechatrommer]

I opened motor cover and saw that its base is dirty

next move... pull out the whisker (stirrer?) the black plastic part, and then pull out the amarture out of its body. i suspect the repair part is like mentioned by others... cleaning rust etc and oiling due to stucked motion. the coil looks clean so i'm not sure if they are burnt from inside, resistance check by a DMM might tell something? next lesson, putting it back together, hint: you need to "dilate" the brushes in order to put them back in, or otherwise by some specific skillful motion and rotation back and forth.

reference:


lesson learnt (or havent?) congratulation! next time dont peel out the lock (upper) until its broken (the metal part that hold the brushes' holder, the white plastic). if you want to go further, you can learn how the coil is wounded by de-wounding it, but that require buying a new one to continue whisking which i highly suspect, in any way will be the case. thats how we gain experience, we pay a price for a piece of knowledge. nothing free in this modern world. keep messing around

[Mechatrommer]

correction... not trying to discourage you with previous post, but if you are lucky, which mostly the case with me and onehunglow products... with the right fix procedure, eventually you might be able to make it a longer lasting product. onehunglow is nice in the sense that its cheap and you only need a bit to touch up to make it working charmingly and satifactorily

[Boris_yo]

WTF is wrong with a teaspoon?

Battery operated coffee whisker is more convenient at rapidly dissolving coffee and sugar. It also saves you time stirring and makes foam on top. Seems like useless gadget first but it is not so.

[Gigawatt]

Throw it away ! simple ! Then use the manual method no electrical power required then

[Telequipment]

 I've seen those motor on E-bay, really cheap to buy, get a couple spare for next time, good on you for keeping the old stuff going.

[SeanB]

Battery operated coffee whisker is more convenient at rapidly dissolving coffee and sugar. It also saves you time stirring and makes foam on top. Seems like useless gadget first but it is not so.

Simple solution is not to use sugar.......... I like my coffee unsweetened, and will drink it black. With or without milk, with or without water and with or without coffee, I will take it, just need at least 2 of the components. If there is no coffee I just put in either Earl Gray or Twinigs or 5 Roses.

[GeoffS]

WTF is wrong with a teaspoon?

Battery operated coffee whisker is more convenient at rapidly dissolving coffee and sugar. It also saves you time stirring and makes foam on top. Seems like useless gadget first but it is not so.

The proper solution is to drink brewed coffee, not that instant rubbish. Give up the sugar and you'll be able to live without your whisk.