Washing machine - brushes replaced, motor is smoking...

[GetArmy]

Hi all,

WM is a Bosch, 5 years old, average family use.

Recently is has been making a 'ticking' noise when the motor is under load (which I now know to be arcing) and has caused the circuit breaker to trip a couple of times.

More recently, the motor stopped working in the middle of a cycle. A friend who knows a little about these things said that if striking the motor with the rubber end of a hammer causes the motor to spring back into life then the fault is most likely with the carbon brushes.

I tried this and the motor did come to life. This happened fairly predictably over the next few cycles... motor dies ... give it a knock ... complete the cycle. Watching the machine running (with the back off) I could observe the reflection of the arcing on the WMs metal floor.

I ordered new carbon brushes from ebay. Not genuine bosche ones (£24) but compatibles (£8).

I fitted them last night. Sure enough, the old brushes were worn right down. I put the machine on to do a wash. I immediately noticed that the arcing was still present. I also noticed that the motor was generating an electrical smell and soon spotted wisps of smoke coming from the motor casing.

I immediately stopped the cycle and checked the brushes to make sure that I had installed them properly. They were in correctly. I noticed that one of them was hotter than the other. The cooler of the two was also not moving as freely as the hotter one. There was a slight protrusion in the brush holder which prevented the brush from sliding smoothly. The protrusion had rubbed a groove in the edge of the brush so I 'enhanced' the groove with my screwdriver and it now slides smoothly.

I also checked out the copper strips on the spindle that the brushes make contact with. This looks quite worn. Actually I'm not sure if it's worn or just dirty. There is a definite line of wear around the strips which looks like it could have been caused by the end of the braid/wire which was visible on the end of the worn brushes. I gave the copper strips a wipe with kitchen towel and a little carbon powder came off them but mot much. The gaps in between the copper strips didn't look to be particularly full of carbon dust.

I reassembled everything and allowed the washer to do another cycle. The motor was still smoking gently throughout all parts of the cycle. Perhaps less so on the spin but that may be just the increased air movement dispersing the smoke. I think that the arcing may have been getting a little less but not so, the smoking.

Is this normal for a new set of brushes? Although the old ones were completely worn out and arcing, they never caused any smoke or a smell. I'd rather avoid having to pay £128 for a new motor if possible!

Any ideas?

Thanks

Mike

[Bruce]

Perhaps the Bosch brand brushes would bed in more quickly? Unless you are sure that the £8 branded brushes are exactly equivalent to the £24 Bosch brushes, I think I would probably have spent the £24 to save the £128, rather than taking a risk on the £8 unbranded set. The brushes will have had square ends and you will need to give them time to bed in and take the shape of the commutator. Until that time there probably will be some arcing, but it will reduce as they bed in.

I replaced the brushes on a Hoover washer and they took about 10-15 washes before they fully bedded in.

[Harry Bloomfield]

Brushes really need to be either pre-formed to shape at the face, or shaped by hand. Usual way is to wrap a strip of fine sand paper around the commutator and push the brush against this as you spin the commutator. Brushes should always be refitted in exactly the same orientation to the commutator as when removed. Carbon dust in the caught in the commutator gaps can short out and cause damage to the commutator - always clean it out.

[meow2222]

he =EF=BF=BD24

Carbon between the comm segments might possibly be the cause of the excess current/heating/smoke, but I'm certainly not saying it is, there are other possibles. Easy place to start though.

NT

[meow2222]

the =EF=BF=BD24

Motor overcurrent is also caused by partial winding shorts (damaged insulation), for which the only solution is a new motor or rewind.

Some WMs arent worth putting a new motor in. When that happens its possible to keep a damaged one running long term by fitting a series impedance. Its a bodge, but works, and is a useful option for people on benefits etc. It reduces spin speed a bit. If thats an attractice option, you should test it only using an impedance, as any further smoking will quickly and heavily worsen it, quite likely killing it.

NT