Motor repair - Kenwood mixer

[Iain Mac Donald]

Recently our oldish KM600 Kenwood mixer started playing up. Strange noises and even stranger burning smell. Upon investigation discovered a lot of "carbon" dust distributed around the motor. Motor was sparking a lot around the area of the carbon brushes. When removing them there were white scorch marks on the leading edge of the carbon brushes. However, the brushes otherwise seem to be in good condition and are about 15mm in length.

One thought is that the carbon brushes are mounted on another material and it is this material that is now deteriorating. Without seeing brand new brushes I can't be sure.

It might, of course, be something entirely different causing the problem. Any ideas anyone?

[sPoNiX]

A short in one of the windings? Are any of the commutator segnemts discoloured?

sponix

[Iain Mac Donald]

Once I had taken the vacuum cleaner to the whole thing - covered in old flour etc. - everything seems to be in order. There is some discolouration in the area nearest the brushes but this would seem to be effect rather than cause.

Are any of the commutator segnemts

Yes. The copper (?) coating on one segment is gone but looks more like cosmetic damage than anything major. Do you think this is significant?

[Dave Fawthrop]

| On Thu, 03 Nov 2005 14:37:08 +0000, Iain Mac Donald | wrote: | | >Recently our oldish KM600 Kenwood mixer started playing up. Strange | >noises and even stranger burning smell. Upon investigation discovered a | >lot of "carbon" dust distributed around the motor. Motor was sparking a | >lot around the area of the carbon brushes. When removing them there were | >white scorch marks on the leading edge of the carbon brushes. However, | >the brushes otherwise seem to be in good condition and are about 15mm in | >length. | >

| >One thought is that the carbon brushes are mounted on another material | >and it is this material that is now deteriorating. Without seeing brand | >new brushes I can't be sure. | >

| >It might, of course, be something entirely different causing the | >problem. Any ideas anyone? | | A short in one of the windings? Are any of the commutator segnemts | discoloured?

Raised commentator segment, it happens sometimes. Spin the com, **by hand** under your finger, that should detect it

[Chris Bacon]

The segments should be solid copper - you could try polishing the commutator with a dry cloth and some meths, and ensuring the grooves between the segments are clear - don't scratch the commutator surface, or undercut the segments.

What does the discoloured segment look like?

[Iain Mac Donald]

Just what I thought - yet underneath it looks more silver/grey!

Tried that already. No difference.

and ensuring

Kind of silver/grey as if the copper layer (?) had been taken off. Only one segment, neighbours are fine.

[Iain Mac Donald]

Can't feel it with my finger (need to get it re-calibrated!) but there does seem to be a vague click as the damaged segment passes the brush.

Should I ready my junk bin for the imminent arrival of the arm?

[Dave Fawthrop]

| Dave Fawthrop wrote: | > On Thu, 03 Nov 2005 15:00:55 GMT, [e-mail] (sPoNiX) wrote: | > | > Raised commentator segment, it happens sometimes. | > Spin the com, **by hand** under your finger, that should detect it | | Can't feel it with my finger (need to get it re-calibrated!)

No! fingers can detect 1/10,000 inch, so the comm is good enough. Classic test with jo blocks.

| but there | does seem to be a vague click as the damaged segment passes the brush. | | Should I ready my junk bin for the imminent arrival of the arm?

:-)

[Iain Mac Donald]

Don't have any and my rudimentary micrometer doesn't notice anything.

So what is the conclusion? Individual components, except for brushes, are not available. Only the whole motor (new model including control unit) is available at £100 plus.

[Chris Bacon]

plus £3.99 p&p

[Chris Bacon]

I re-open this to add that e-bay may be a source - Kenwood machines share parts, see the above URL.

[Iain Mac Donald]

Aha! That is a much better price. Do you know if this is for the early model KM600 motor (which I have) with grey casing or the later model with black casing. Maybe the arm fits both models?

[Chris Bacon]

I'm afraid I have no idea - I simple let my fingers Google, in an idle moment - you could try their "parts enquiry" link on the LHS of that page....

[Iain Mac Donald]

Thanks everyone. Maybe saved a few pennies and learned something along the way.

[daddyfreddy]

You may be looking at the wrong thing here. Had a similar problem with my sister's Kenwood. It's quite an old heavy duty beast and the top half swings up. This is where the problem was with hers. Basically the mains cable needed renewing as it suffered fatigue from the continual opening and shutting. Worth a look.