My kenwood chef is about 20 years old .The last time I used it I smelt burning.I switched it off and left it.It is still working but I am afraid to use it .Any ideas.

leanora rea, February 2009

I have a 20 year old Kenwood chef KM201 which is seldom used. Recently I used it and there were smoke coming out from the machine when running.

It is traced to 2 capacitors on the circuit board. I had them replaced as well as the TRIAC, 2 small capacitors (1 pico farad ) and the 55 ohm resistors which were located near to the burnt capacitor ( 0.15 micro farad) as they showed signs of being burnt on their surfaces.
The machine is now working well now.

I tried to understand the circuit as how the TRIAC controls the speed of the machine. I have yet to fathom this out. The speed control knob only moves the speed control board up and down relative to the motor.

Any one know about how the TRIAC controls the speed of the motor?

Is there any schematic of the circuit board I can get my hands on.

Wong KL, January 2015

the problem is caused by two capacitors1 .1micro farads the other .15 microfarads they serve for filtering there's even a small resistor that should be replaced it is a 56ohms 3 watt . the problem is how to reach to them it can also be a small micro switch which is arching don't leave it plucked on mains it can catch fire believe me.

charlie, March 2009

I am not familiar with the exact workings of the KM201, however the older models have two things that cause smoke or burning smell from the speed control circuit.
1. Models before electronic speed control have a large resistor which is designed to get hot and if oil or grease drops on it then it will be burnt off. This is not a problem.
2. (more likely) Electronic speed control models have large capacitors which are prone to fail, particularly after long periods of storage or no use. The components are readily available and easy to replace.

You might be able to see the problem if you turn the machine upside down and look into the base of the motor with a torch. The capacitors may be expanded or have burst open and the small resistors will appear to be burnt and have lost their colour codes.

Hugh, February 2009