hotpoint washing machine motor brushes

[kenknott]

On Christmas Eve (!) our washing machine packed up with a loud bang! The fuse had blown. Against my better judgement my wife persuaded me to simply replace the fuse and I was surprised when it appeared to do the trick. However, not for long! The fuse then blew with another loud bang.

I am wondering if this behaviour is likely to be the motor having burned out or simply that the brushes need renewing. I've removed the motor and the brushes. There is clear evidence of electrical burning and black dust, but both brushes are intact, although I notice that one is a few millimetres shorter than the other.

To me the logical next step is to risk replacing the brushes and if that does not work decide on whether to try to test the motor. Anyone have any suggestions or advice?

Thanks.

[Bob Minchin]

I can't think of a situation where defective brushes would lead to a fuse blowing. The motors are series wound and so brushes not making contact, will reduce supply current rahter than blow a fuse.

It could be that the armature has developed a short on some sections and if the motor comes to rest with these sections in contact with the brushes, the fuse might blow on re-starting. Motor testing is not trivial unless you have some reasonable specialist equipment such as a variac. Do not be tempted to connect diectly to the mains supply. The unloaded speed of these motors may destroy the windings.

I assume that when you replaced the fuse, that the motor did run for a while, or did it blow as soon as the the motor first turned after filling?

if the former, I would think the motor is shot. If it were the controller at fault, I would expect the fuse to blow instantly.

Good luck

Bob

[EricP]

The brushes are a fiver and take half an hour to replace. Worth a try before calling the repair man?

Although I have never had blown fuses from brushes. Smells, firework displays and stuttering spins, but not fuses.

[kenknott]

the motor did run again after replacing the fuse. in fact the washing machine ran for in excess of 30 minutes before the second blow.

[kenknott]

my wife says there might have been stuttering spins, but is not sure! I wondered that if the motor stopped turning (because of a faulty brush), then maybe the current through that particular winding would increase enough to blow the fuse. If there were no movement there wouldn't be any back-voltage. Maybe I'm just wishful thinking! I'll see what others say but will probably change the brushes as a first shot at a solution. Thanks.

[EricP]

You are correct, motors like these are very crude and when they stop with power on the brushes, a short circuit is very likely across the segments.

If you do the brushes, be very gentle if you have to bend the metal clips to get the old out and new in. They break very easily and fabricating a replacement can be very boring.

[raden]

In message , [e-mail] writes

Has a wire come loose which has chafed and is causing an intermittent shout ?

[BigWallop]

The build up of carbon from the brushes can cause arcing to the casing of the motor, so if the area around the brushes is heavily coated with carbon powder, then this can cause enough of an electrical arc to blow the fuse in the plug.

You may be able to clean the motor enough, and extend the springs on the brushes enough, to allow the machine to run for a little while longer until you get to the shops for new carbons. A lot, if not all now, motors in the likes of washing machines have carbon brushes already set in holders that just slip into the motor casing. To replace them is as simple as removing one wire spade connector and pressing a moulded clip on the holder to remove it from the motor casing. Slide the new holder in to place and connect the wire again.

Remember to clean all the old carbon dust from the motor with a vacuum cleaner and a small paint brush. If the armature in the motor, the bit that actually spins, is showing signs of burning, then gently turn it and place a fine grade sand paper on the part the brushes sit on to clean them back to the bare metal. They should be quite shiny and clean to make the motor run properly again.

Good luck with it.

[Grimly Curmudgeon]

It was somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember raden saying something like:

It'S pERfeCTly pOSSible, I WOUld thInk.

[raden]

In message , Grimly Curmudgeon writes

There's nothing worse than a nasty bit of chafing

[BigWallop]

But the prescription cream and loose underwear can help a lot. :-)

[Peter]

1/2 hour !!!!!!!

Peter

[Lurch]

On Tue, 28 Dec 2004 13:23:18 +0000 (UTC), "Peter" strung together this:

That's including the coffee break half way through and a test cycle.

[Bob Eager]

And unstacking the tumble dryer.

[Aidan]

Would it have reached the stage in the cycle where the pump is activated? My Hotpoint suffered nasty chafing of the wires supplying the pump power, resulting in a short and fuse blowing at the end of the wash cycle.

[kenknott]

burning

casing of

connect the

vacuum

Replacing the brushes didn't work, but replacing the motor did! Thanks to you guys for your helpful advice and comments.