Bernina Record 830 - Motor Checking - Brushes and Capacitors

If you're the lucky owner of a Bernina 800 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.

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.

If the capacitors fail, they can cause a few issues. For one, I have seen them cause excessive heat and melt the motor casing. They also 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.

Models with inspection ports for the motor brushes can have their brushes checked without removing the motor.

This video covers many models of the Bernina 800 series sewing machines, such as 801, 802, 810, 810b, 830 and more.
You'll see the Bernina 810b and 830 used here.

Removing the motor is relatively easy and can be done with appropriate screw drivers. The end cover needs to be removed and the motor drive belt slipped off the pulley. The two motor mounting screws, accessible from under the machine, need to be removed.
Once the mounting screws are free, the motor can then be lifted away from the base but will be connected to the machine with one or two pairs of wires. Those wires are for the light and speed selector switch, if installed.
The wires run to terminals in behind the motor cover. The cover can be removed and if you're careful you can service the motor without disconnecting any wires from their terminals. It does pay to take a note of what terminals each wire attaches to because it is easy to accidentally disconnect them.

The capacitor set and motor brushes can now be accessed.
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.

Check the motor brushes by undoing their retaining caps and removing the spring which holds the carbon brush on one end. If the brush is worn, it would pay to have both of them replaced.

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