This page gives free diagnostic and advice for competent repairers who may want to confirm and check a few things before replacing carbon brushes in a washing machine motor. The principles of diagnosing carbon brush faults and deciding if they are worn, or faulty and need replacing are exactly the same as for any motor with any carbon brush across all brands.
How do I know if I need to fit new carbon brushes?
You should be competent enough to be able to diagnose and repair this type of fault because other faults could be present. You should always test a motor’s insulation with a suitable insulation test meter to ensure electrical safety using 500V DC. If carbon brushes are worn, the motor will either stop running or will run half-heartedly and make a crackling or grating noise. If you observe lots of sparking from inside the motor then this is also a symptom. Note that minute sparks are usually normal though, and that if a motor has stopped running, there could be other faults on the motor itself, or on other parts or connections in the washing machine. Faulty motors can also blow the control PCB.
Worn Carbon brushes
Here is a picture of a pair of worn Hotpoint carbon brushes. Both carbon brushes are approximately 80% worn but the carbon brush on the left is still making good contact with the armature.
The difference between the two is that the faulty one on the right is charred and sooty at the tip. It’s taken on a charcoal-like appearance and there is evidence of burning present. The good carbon brush on the left is smooth and shiny at the tip which shows no sparking has been occurring.
If both brushes are smooth like the one on the left, then they are still making good contact and are not likely to be causing any symptoms. However, if they are as worn down as this they clearly still need replacing. It’s just that maybe the fault you currently have is caused by something else.
This carbon brush is OK
This Hotpoint (or Creda) carbon brush is approximately 20% worn. It is the later (laminated type)
The tip of the brush (that runs against the armature) is shiny and smooth, with no evidence of burning and is therefore perfectly alright.
It is possible for a carbon brush that is not worn down significantly to stick inside the holder (which is spring loaded) If this happens, then as the brush surface wears through normal usage, the brush doesn’t get moved up and stops making contact with the armature.
If this happens, then the tip of the carbon brush will look charred like the 80% worn one above.
Complications on carbon brushes
This carbon brush is approximately 50% worn but something has gone seriously wrong. If yours looks like this then there could be problems with the other parts inside the motor.
The tip of the carbon brush is charred but note the arcing damage to the brass holder which has been caused by excessive sparking and flashing inside the motor.
If the tip of the carbon brush is damaged to the extent that there is a chunk broken off, (not shown here) then there is a good chance that a raised commutator bar on the armature has caused the fault. This would require a new armature (or sadly more likely these days a complete new motor).
If the washing machine has also fused, then this is evidence of electrical shorting inside the motor which you need an insulation test meter and electrical knowledge to diagnose and repair.
Also, if there is damage like this on the brass holder (and especially if the washing machine fused) then the TOC could have blown also. This is then not a simple case of replacing the worn carbon brushes and no longer a straight forward DIY repair job.
Want to buy some carbon brushes?
More on carbon brushes
- Fitted new carbon brushes but the motor still doesn’t work
- Fitted brushes now motor sparking a lot
- Main diagnostic advice for motor not running
- DIY safety section
- How to fit the older Hotpoint / Creda carbon brushes
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