One for the washing m/c repairers

Bosch drive motor failure on spin function. Failed to reach full speed and then tripped out the house RCD.

Google seems to imply this is terminal for the motor. On examination the carbon brushes have worn to the point where the copper inserts have marked the commutator.

Set of brushes are cheap enough but replacing the motor at 175-200ukp seems poor economics.

Any experience?

Reply to
Tim Lamb
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Our Siemens (also made by Bosch) did the same replacing the brushes fixed it. If you have a badly scored commutator you may find you go through brushes rapidly but for the the price they are and the 20 mins to fix it is worth a punt.

Richard

Reply to
Tricky Dicky

In message , Tricky Dicky writes

Bosch set (30ukp) on order. I'll give the comm. a tidy up before re-fitting.

Ta.

Reply to
Tim Lamb

AFAIK the flexible braided wire should be short enough not to allow that to happen.

Treat it to some new brushes and if it continues to trip the RCD strip it down, inspect, and clean the carbon deposits off the commutator, brush carriers etc.

Reply to
Graham.

One needs to be thorough with the carbon, which can be slow. Last time I resurfaced a WM commutator by running it on 12v (IIRC) and using a file. Sometimes insulation trouble can be sorted out by mounting a motor on insulating mountings.

NT

Reply to
tabbypurr

bought a recon motor some year s back for around 75 exchange when mine did this.

wasn't brushes. Was a short from a winding to earth on the armature.

Reply to
The Natural Philosopher

75 sounds better:-)

These brushes are badly worn. I wonder if the copper in contact with the com. leads to excessive arcing.

I've given the com a clean up with emery cloth and raked out the segments. Thorough blow through with compressed air and I'll see what new brushes achieve.

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Reply to
Tim Lamb

if you have it out check resistance to the frame/armature stampings from the commutator segments. Its rare for arcing to blow an RCD unless you have shit loads of electronics (RFI caps) between live and earth in the house and a rather high impedance supply.

Reply to
The Natural Philosopher

On the desk beside me. I don't have access to a Megger but I can try my multimeter.

I don't think there is anything high impedance about an agricultural 3 ph. supply and I'm not aware of any line/earth shunts other than what is hidden in our various bits of domestic electronics.

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Reply to
Tim Lamb

Open circuit on 20 meg range between frame and all comm segments.

Fair bit of carbon dust came out with the compressed air.

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Reply to
Tim Lamb

Remove the RCD, they are pansies and trip for anything.

Reply to
James Wilkinson Sword

I was going to say, this sounds like either a very badly designed motor or some malfunction has caused the scoring. I seem to recall mentioning this once before on here when somebody found that the brush replacement still intermittently gave error codes. Back in the day when I had a machine made by Service, this exact same problem is what took it down. it also had started to get dry joint issues all over the place and I thought getting that all fixed would make it last, but it lasted three months till it spluttered went bang and blew the fuses. Comutator basically knackered.

Such is life. Brian

Reply to
Brian Gaff

I'm not sure who mentioned it, but on some motors the comutator is basically a pcb mounted on the back and the segments are etched into it, whith brushes pushing against it. These el cheapo motors seem to fail a lot. Often found in things like shredders etc. Brian

Reply to
Brian Gaff

Why not fit a cut off nail in the fuse holder while he is about it. Should make a nice fire. Brian

Reply to
Brian Gaff

In message , Brian Gaff writes

I suppose a washing machine is not monitored in the way a vacuum cleaner or electric drill might be: allowing deterioration beyond that anticipated by the motor design.

These particular brushes are able to travel and wear right down to the point where the flexible conductor is fused to the carbon.

I am hopeful that the 30mA trip has protected the motor from serious damage. We'll see:-)

Reply to
Tim Lamb

oh, mine showed about 3k with a simple multimeter. I disasembled the whole motor and left it that way when swapped for a rewound one....'well saves us the job of doing it mate' ... :-)

In which case I suspect you have an earth leak.

Reply to
The Natural Philosopher

field coils as well? But that's looking like good news...

Reply to
The Natural Philosopher

That was what fixed the RCD tripping issue for me on our AEG Lavamat.

It would (suddenly started to) trip instantly at power on but not with the motor disconnected.

I was very surprised to see how much carbon dust came out of it.

Cheers, T i m

Reply to
T i m

In message , T i m writes

Sadly there seems a bit more to this than new brushes and a blow through.

Reassembled last night but motor not being energised. Yes I did put the brushes in the correct way and am reasonably confident that the connections were properly re-made.

Oh well. There is a back up m/c in the *West wing* and washing lady says if I want clean smalls I'll need to do a swap.

Test access is from underneath the m/c so difficult to check in normal operate mode.

Thanks to all who contributed.

Reply to
Tim Lamb

I'm sure they were ... so I wonder if as the brushes failed it took out something else?

;-)

Normally the tops come off these things by removing a couple of screws at the back or there is also / often a back panel you can remove (often allowing you to get to the belt / drive ring / bearings but little else)?

Mum still has a very old washing machine (Hotpoint?) I can remember brazing a motor bracket back on when I feel was in my 20's (now 60) and a very much younger Whirlpool sitting beside it that did belong to her granddaughter but requiring new bearings (that I will change when I getroundtuit). ;-)

If you get any time and can see any of the electronics you might find something as simple as an on-board fuse or some such?

Cheers, T i m

Reply to
T i m

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