Brush motor repair

Hi Folks, anyone got any good ideas? I'm hoping to resurrect the YDK motor in a Dyson DC14 vacuum cleaner. It's only 15 years old, and on its second set of brushes, so it's too young to let die... If I can repair it, I might be able to offset the brownie points earned against having to use the horrible thing, so it's worth a few hours of cursing.

I've discovered that an armature winding wire has broken, just at its junction with the commutator. Of course, it has to be one of the wires that lies in the inner layer of the obliquely-orientated wires to and from the commutator bars, and there's no slack. Assuming I can extract the armature, I may be able to winkle about 1 cm of the broken wire out from under the others, into an accessible position, to graft on a short length which can then be joined to the commutator.

It looks like an awkward job, requiring micro-surgical techniques. Has anyone any tips or suggestions relevant to this sort of endeavour? Should I attempt to make a mechanical junction at the commutator (if possible), rather than, or in addition to, soldering the new wire in? It looks like the winding wires have been connected to the commutator by crimping or, possibly, spot welding (difficult to see with the armature in situ, but no solder evident).

Hi Kiwi bloke,

You may be able to make a soldered wire repair, but you will probably find that as soon as the motor spins up the centrifugal force will simply pull your joint apart.

Quite - my worry too. I was expecting to have to bind any soldered joint. 'There has to be some way of fixing this,' he said, in quiet desperation...

If you're going to use soft solder to make the connection to the commutator, ensure that you use a high melting point type. 'Comsol' used to be the product to use , but I'm not sure if it's still available.

Be very carefull you do not melt the solder at the next join on your armature segment either side of where you are resoldering good luck

Regards Brin

Well, I feel a bit let down. So much knowledge and wisdom here, but no-one's waved a magic wand and told me how to fix this wretched armature wire. Come on you lot! Please!

The winding is looped around its connection to the armature bar, a radial extension of which is bent over the loop, trapping it, and peened flat. I've managed to lift the peened-over bit, and release the loop. The break is just at the side of the armature bar. There is no slack, and only a few mm of wire to play with. I think that mechanical connections, perhaps with added solder for electrical integrity, are the way to go. I'm thinking of squashing a small brass ferrule around the wires, with a new length of wire going to the commutator, but it won't be easy...

At the moment, the whole thing has been put aside in the 'lacking inspiration' basket. Has anyone any better idea for a method of repair (inspiration isn't happening...)?

resistance weld it- that's probably how it was made in the first place

BTW Dyson=junk+marketing IMHO

Agreed, however isn't that true of almost all 'consumer goods' these days? In fact it's worse - the wretched junk we have to choose from is carefully designed to fail. Marketing + Accountants - Engineers + Necessarily Passive Consumers = The Unacceptable Face of Capitalism?

The DC14 isn't a bad vacuum cleaner compared to the modern junk that Dyson sell. It is instructive to look in the vacuum cleaner skip at your local recycling center. Just count up the large amount of Dyson's in there!

If you want a decent, long lived vacuum cleaner, that has spares back up, for even the first model, then get a SEBO. They are robust, well engineered products that will last and last.

Andrew.

KB, go to the local tip, ours has a container full of duff dysons, you may be able to get a spare there.

CG

Andrew - thanks, I hadn't heard of SEBO. A quick search reveals the model selling for about 310 GBP in John Lewis is magically NZ$1200 - about 600GBP - here. We get ripped off like this all the time. That's why repair becomes 'do or die'. I guess, for similar reasons, the local recycling (joke in NZ) centre doesn't have skips containing any Dysons - otherwise it's a good idea Chris. Luckily, it's not all gloom in NZ. We have only one active (known) case of Covid-19. Unfortunately, the economy is now wrecked, and the national debt is ridiculous. The government is throwing money around, all over the place, with no apparent idea of what it's supposed to do. Guess who will pay.

If you want a cheaper SEBO, go to "Manchester Vacs" They are cheaper than John Lewis and carry all the spares. They also dispense good advice and there is a Vacuum cleaner forum too!

They are also Dyson agents but got fed up of the modern Dyson tat and took on a SEBO agency as well.

Andrew.

Just a thought.

In the unlikely event you do manage to winkle out enough wire and re-make the connection you may be able the give that joint a little more mechanical support by encasing it in some epoxy.

You may need to add a similar amount diametrically opposite to restore balance to the armature.

Well, this thread has had 774 views, so someone might still be interested to know what happened...

Micro-surgery delivered the two ends of the broken armature winding into a position where they could be slipped into a small-diameter ferrule, with a third wire added, to make contact with the commutator. The wires were bent over as they exited the ferrule and cropped. The ferrule was crimped, the joint was soldered - for electrical integrity - and epoxy was dribbled around and heat-cured, to ensure electrical insulation and in the hope that no movement would take place. The third wire was connected to the commutator, crimped and soldered. That took a couple of patient hours, and a lot of impatient expletives.

Going around the commutator, measuring the resistance at between diametrically-opposed commutator bars showed consistent resistance, except for one position. It turned out to be a loose commutator-winding connection, so it was re-crimped and soldered. Opposite and adjacent resistances all consistent, and no continuity to the armature's body. Yippee!

So the motor was reassembled, correcting some distortion of the flimsy frame caused by use of a bearing puller. Apply mains (with a soft-starter in circuit - because I could). Motor ran up to speed without drama, but when at full speed, the impressive 'ring of fire' around the commutator was present, as before. Bad words. I assume something in the winding moves under centrifugal force, either breaking a widing or shorting to 'earth', or there's an earth leakage I didn't find at low-voltage testing.

New motor required. Pity...

Edited By Kiwi Bloke on 14/06/2020 11:29:54

Never mind, you gave it a try and that's what matters.

FWIW I tried to repair a Metabo commutator which metred out just fine electrically but also had the ring of fire arcing problem. It was heavily worn but looked ok. Field coils were fine. I checked and cleaned between the segments very carefully and there was no sign of any bridging but I never did find the reason.

A new rotor cured it.

In the UK a new motor for a DC14 for £18 or less, are they much more in NZ? Regards Pat

You now know why Mr Dyson is a billionaire.

I have in my shed a vax multicleaner still going strong and all original, one of the very first models it doesn't seem to mind what it suck up, oily swarf, loads of sawdust even sucked up the sand that my neighbours young children filled a drain up with, since that first one we have had two more of them , the second one lasted just over 5 years and was used nearly every day, we have always had really hairy dogs! the second one's motor started crackling and smoking, so we are now onto our third one, two weeks old and cost just £129 delivered, less than the first one all those years ago.

In between the first and second we tried dyson, a smaller Vax, Electrolux and hoover, all professing to deal with pet hairs but none have the capacity of the Vax.

If you can live without an upright cleaner, get a Numatic Harry, made in England.

Numatic HENRY ( or is there a Harry?)

Yes indeed there is a Harry, 

Edited By V8Eng on 14/06/2020 21:05:57