Hi all,

I have a kenwood kmc550 model and it has a problem on the speed of the motor.
For the first 15/20 seconds, the speed seems to be following the position of the knob. Then it falls down to the slowest speed.
Even the pulse position, keeping it for more than 20 secods, falls to the slowest speed.
I have changed the whole control speed board but it works the same.
Then I thought that the problem was on the motor.
I dismounted the motor and found out that there is a sensor inside, looking like a resistor, yellow, with a CEC writing on a plastic wrap on it. This sensor is placed just close to a iron ring, so I deducted it is a speed sensor.
Can anyone help me understanding what to do?
If this sensor is broken, how can I replace it?

scambias, November 2011

mixing speed selector only select one speed-fast

jim, October 2021

speed selector only operates at one speed- dast

jim, October 2021

for: mech monster
I have seen the brushes and they look still ok.
How they could impact on the behaviour I get? Their aim is to give current to the rod so since they touch the rod it should be fine. Besides, the slowing down of the speed is not when I turn on, but just after 20 seconds. And if I switch off and on again, it stays still 20 seconds and then it slows down. It looks to me as something related to a reactive component (condensator or inductor).

scambias, November 2011

I have more infos...
It is a small axial inductor with ferrite core.
It should be used to "feel" the speed of the rod, since around the rod there is a magnete ring which rotating creates a voltage around this inductor. This tension is used by the circuitry as a feedback of the speed.
Anyone can confirm it? I need to know the inductance of this inductor so I can replace it

scambias, November 2011

you have identified the thermal cut off ,this isn't at faut here as you are getting motor speed .the thermal cut out senses the heat emitted from the motor.if too much heat is detected the motor shuts down to protect the armeture and windings.have you inspected the carbon motor brushes ? if these two little fellows wear down ,then you will almost certainly get the problem you are having.the speed of the motor is determined by the part you have already replaced.

mech monster, November 2011

I can post a picture, is it possible?

scambias, November 2011

I have removed the plastic wrapper and it looks like a little solenoid. I have measured the continuity and it seems to be open circuit.
What is a thermal cutout?

scambias, November 2011

sounds more like a thermal cutout to me??

Dav, November 2011