Bernina Record 730 - Motor Checking - Brushes and Capacitors

If you're the lucky owner of a Bernina 700 series sewing machine it would pay to check the motor, especially if the machine has not been serviced for a while. You may also want to do this if you have recently acquired the machine and you don't know its history.

Do not remove the motor without unplugging the power cord. There are live wires in behind the motor cover if the power cord is plugged in.
If you don't feel comfortable doing this sort of work then leave it to your mechanic or an electrical appliance repair person.

Index:
0:00 Introduction
0:24 Explaining when and why it's a good idea to check the motor
1:13 Removing the motor
3:45 Accessing and checking brushes
10:28 Accessing and checking capacitor assembly
17:30 Assembling motor
20:38 Installing motor
22:27 Conclusion

Before plugging the machine in to test or use the machine, it's a good idea to check the motor brushes and capacitor set.
If the brushes wear out completely the motor will be damaged and it can be expensive to repair.

Check the motor brushes by removing their carriers. This can be awkward with this model. Certainly not as easy as removing an end cap nut like many other sewing machine motors.

If the capacitors fail, they can cause a few issues. They can fail with a bang and a puff of stinky smoke which may give you a fright, not to mention your machine may run by itself.

This video covers many models of the Bernina 700 series sewing machines.

Removing the motor is relatively easy and can be done with appropriate screw drivers.

The capacitor set is a set of four capacitors, two X class and two Y class for electrical noise suppression. They can be visually inspected but that's no guarantee of their life expectancy. They could still fail at any time.
Imminent failure is apparent if the capacitor set housing is split, leaking, bulging or all of those things. If that's the case then replacing them is recommended. You can use the machine without the capacitor set by unplugging the four terminal and removing it. It's not recommended using the machine like this for an extended period but you can do so at a pinch.

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