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Nuova Simonelli Mythos motor not starting during busy times

Postby craigcharity on Thu Nov 10, 2011 4:13 pm

Hi World:)

Before I post this, let me tell you how cool it is to have you experts a post away:) so thanks in advance

I recently bought a Aurelia and a Mythos for a real good deal from someone who had bought it from an auction who had got it from a Gloria Jeans coffee shop..... The grinder is in really good nic despite it having being used 84 580 times, thats right, the counter on the grinder says that is the total. I used it for an event this evening and it was going well for a while but when we got busy it stopped working, the motor sounded like it struggled sometimes. When I made the grind a little coarser it finally started turning again and would work for another couple of shots.

Here is what I have done:

I thought it was the capacitor so I changed it, no joy, during busy times it still does it.
I thought it was the motor that was 'bad' inside, but I opened it up and it all seems pretty good, no burned wires and it looked like a new motor, the bearings are good.
The Burrs are really blunt but could blunt burrs really stall a 800w motor? The motor says 250w on it but I chatted to the agent and he says with the capacitor it is rated at 800w.

Do you think I should increase the size of the Capacitor to a 20uF or higher from the original 16uF to help it get going?

I will appreciate any help, thanks.

C
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Postby allon on Thu Nov 10, 2011 6:32 pm

So, when it was not working it was making noise, or struggling?
LMWDP #331
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Postby craigcharity on Fri Nov 11, 2011 12:34 am

It hummed as if the motor was trying to turn
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Postby RayJohns on Fri Nov 11, 2011 4:06 am

craigcharity wrote:The Burrs are really blunt but could blunt burrs really stall a 800w motor? The motor says 250w on it but I chatted to the agent and he says with the capacitor it is rated at 800w.

Do you think I should increase the size of the Capacitor to a 20uF or higher from the original 16uF to help it get going?
C


If the motor is 250 watts, then it's a 250 watt motor. The circuit with the capacitor will give it more torque, but it won't make the motor over 3 times more powerful. Keep in mind that a Watt is a measure of the amount of work done over time. Torque is the willingness to turn. Watts would be more like HP, which is more the ability to move something heavy (or do work).

If you start changing the capacitance, you will most likely throw off the resonance of the circuit and that could cause more problems than you solve. Keep in mind, the circuit is tuned, so I would be careful fooling around with stuff, unless you know where you are trying to head with this. A higher micro farad cap would take longer to charge, so you might actually cause the motor to run more slowly or be less powerful if you aren't careful there.

Is the motor brushless? If not, I would start by checking the brushes to see if they are burned.

Have you cleaned the inside of the motor? If it's been in a dusty environment (i.e. around ground coffee) for 85,000 cycles, I would check to see if there is a layer of dust inside. Have you taken the motor apart?

Ray
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