Kenwood Chef Speed can't adjust- (new question Dec 09)?

Constantly sinning since childhood -

The weights on the spring are not there for fun I suspect...

As the motor rotates they will move - I can't see your machine but can imagine fast running motor (and weights) bending the spring mounting a little more than a slow running motor. I can imagine the control board being hinged and moving relative to the weights. I see in my mind the contact being broken and power to the motor being cut off - the motor slows and the weights move in and the spring moves down and the contact is re-made and the motor speeds up again. I can imagine the control board being dropped for slow and raised for high speed.

The speed of rotation is controlled by the height of the control board relative to the weights at rest. When the motor is stopped the contact should be made throughout the complete operation of the speed control.

Your control board appears to be having no control over the motor speed - a component has failed i suspect.

Of course all this may just be a bad dream on my part - but it's an interesting fault to consider. yet another sin to my account. And it was 30+ years ago 77 - 78 that sort of time.

Continuing good luck...

Peccavi
December 2009

Thanks Peccavi. Have you sinned?
There is no triac on this model. The centrifugal weights are small and suspended on very rigid metal strips. It is difficult to envisage that they could move at all. I cannot figure how the changing height of the circuit board can affect the speed. I have turned the adjuster screws as much as I dare - to no effect.

Neil T
December 2009

I was poking around in one of these Kenwood mixers about 25 years ago and remember very little.

As I imagine it the sprung weights fly out as the machine goes faster - the spring bends - the contacts move apart and power is cut off from the motor - the contacts soon make and the motor speeds up a bit etc etc.. The nominal distance between the contacts determines the speed setting.

From what you say the speed control on the circuit board just does not care about the contacts - full drive power is constantly being delivered to the motor - the contacts move as far apart from one another as they possibly can - the motor is always at top speed.

If the contacts actually come together when the motor is at rest than the adjustment is probably fine. The issue is with the circuitry that drives the motor - I would suspect the final drive transistor (probably a Triac) but that's just a cheap shot guess.

Good luck...

Peccavi
December 2009

Further info on this from questioner. The gap does decrease when the control knob is turned but for all settiings there is no contact between circuit board and motor in spite of more than one complete turn of the adjusting screws. The two weights on the curved phosphor bronze(?) arms are directed towards the motor - is this OK or have they flipped from pointing towards the circuit board? The capacitors appear OK - no sign of burning nor smell of it..

Neil T
December 2009