Dyson vacuum burnt motor repair

[drummerdimitri]

So one day my vacuum cleaner decided to die on me and upon dismantling the motor, it was clear the rotor and brushes had suffered an ugly death.

I have two options now: Buy a replacement motor from my local distributor or try to find a new rotor as the motor housing is intact but the coiled wire is burnt and some strands have broken off the commutator bar.

Where would I be able to get a replacement rotor? Are these made according to some standards or will it be impossible to find a replacement on Aliexpress?

I have attached a picture of the part that needs replacing so any guidance in the right direction would be most appreciated!

[james_s]

If it's for a Dyson it's probably a custom part. A lot of universal motors like that are made by Lamb and you might be able to find something similar but it may be tricky to get an exact fit. You'll also want to figure out why it burned out, that sort of failure is rare, did the airflow used for cooling get clogged?

Another option that may be possible is rewinding.

[drummerdimitri]

If it's for a Dyson it's probably a custom part. A lot of universal motors like that are made by Lamb and you might be able to find something similar but it may be tricky to get an exact fit. You'll also want to figure out why it burned out, that sort of failure is rare, did the airflow used for cooling get clogged?

Another option that may be possible is rewinding.

Thanks for the tip.

My guess is one of the carbon brushes was no longer making contact with commutator bar and had a very rough surface so there probably was a lot of sparking going on which increased the contact resistance, heating up the enameled copper wires which eventually burnt off the enamel coating (strong sweet smell) possibly causing an internal short and broke some wires off in the process.

The vacuum cleaner has been used for 5-6 years every day and the motor has never been cared for so my guess is this vacuum has suffered a normal death by age.

Will looking into rewinding, I know there are shops that do that locally just not sure if the do it for such small rotors.

[andy3055]

The commutator on that armature looks wasted a lot. If you wash it off with some Gasoline (petrol) you will be able to see how badly damaged it is. If it is only one lead that is burnt, you could carefully lift it a bit and patch and insert a piece of fiberglass sleeving before reconnecting it on to the commutator bar. After that you can do a check using a meter. Check between adjacent bars and see how much of a variation you get going around. If you can feed about 10-15 volts DC on diametrically opposite bars and check the voltage drop between each 2 adjacent bars at a time (called a drop test), you will know if it is still usable. There should be no major difference of voltage drop between each pair.

If everything checks out good, you still have to turn that on a lathe of some sort and "dress" the commutator and then undercut the mica a bit between the bars.

Here is some info for you:

https://www.groschopp.com/how-to-check-a-motor-armature/

[james_s]

I'm actually not convinced that the windings are burned up, they could just be coated with carbon dust from the brushes. The commutator doesn't look great but I've seen some pretty badly worn commutators that still worked fine, as long as the wear is in the axis of rotation so the brushes still ride smoothly. Definitely clean it up and inspect it closely before condemning it.

[drummerdimitri]

I managed to clean up the commutator bar with a fine wire brush and some rust removal goo and as you can see, it is in seemingly immaculate condition.

Some of the windings are definitely burned and as you can see some of the wires are damaged so there is no hope for this to work unless someone can re-wind it.

[Gyro]

If you look at the profile, that commutator is badly worn. Ideally a motor rewinder would re-face it in a lathe (assuming that there is still enough diameter to permit it, which is uncertain).

[drummerdimitri]

If you look at the profile, that commutator is badly worn. Ideally a motor rewinder would re-face it in a lathe (assuming that there is still enough diameter to permit it, which is uncertain).

That could well be the case but unfortunately, rewinding is not an option as there are no local shops that do so on such small/fast motors.

I have found what seems to be a suitable replacement in terms of dimensions: https://www.aliexpress.com/item/4000212997998.html?spm=a2g0o.cart.0.0.63f53c00vRZoPJ&mp=1

Not sure about the electrical characteristics as there are no specifications mentioned anywhere but for the price, I'm thinking I should give it a try and if that doesn't work then I will get a replacement motor from my local Dyson distributor.

[andy3055]

Looks promising. However, check the physical dimensions such as core area diameter and width, shaft size/length the bearing external diameter etc. and the number of commutator bars just to be sure. Make sure you get a matching nut as what you have may be different in thread.

I suppose you have thought these factors.

Edit: Most important: Is it the correct voltage for you?

[Gyro]

At that price, you've got little to loose in trying.

[drummerdimitri]

At that price, you've got little to loose in trying.

Exactly so might as well give it a shot. I will be paying an order of magnitude more in case it doesn't work