White Knight tumble dryer - drum not turning

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Not in the UK they are relay or PTC starters no capacitor
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In UK, older ones used to have a start capacitor and relay (starter relay failing was a not uncommon failure mode in old age).
There's no externally visible capacitor in current models, but they are certainly induction motors of some type.
--
Andrew Gabriel

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writes:

Must be damn old I been working on them for 25yrs never seen one with a capacitor only a relay starter
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No it's not, while you can use an oil filled run capacitor as a start capacitor, you *cannot* use an electrolytic start capacitor as a run capacitor. Start capacitors are rated only for momentary use.
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wrote:

Dunno what type of motor would be fitted.
It could be the capacitor (If it has one). They dry out over a period of time and go open/short circuit. You should be able to get a new one for 3 to 4.
If the motor has brushes these could be worn, or the corresponding commutator dirty.
sponix
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On 21 Dec,

Yes, the capacitor failed in ours. You could tell by the smell, though. I'm not sure if it was our current machine (white knight) or the previous.
Spares for our white night were readily available by phone from the manufacturer last time I needed any.
--
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paulfoel wrote:

It's either the capacitor itself, the starting switch if present, or a fault in the motor. I'd check the switch first, if that works then replace the capacitor, if it still won't start then it's probably the start winding in the motor.
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On 21 Dec,

They are usually two identical windings with a capacitor between them. The control box feeds each side of the capacitor in turn for a few seconds. This gives a few seconds of rotation in each direction. If the capacitor (or a winding) is open circuit, it won't start without assistance.
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That looks like the most significant paragraph in your original fault description.
It doesn't run until you poke it... which suggests that there is only a single phase connected, which could be power only to the Main winding or only to the Auxiliary winding (the one via the capacitor).
But even when poked it has no torque.... which then suggests that only the Aux winding is being powered.
It looks like it could be a poor connection to the main winding of the motor, or the main winding itself.
It's an ohmeter job. Locate and check continuity of the main winding, then work backwards along all wires and connections to it.
Perps, in order of probability:-
Any switches, switching or reversing power to the main winding. The main winding itself. Crimps and connections along the wiring.
If no obvious fault is found, do the same ohmeter exercise in the Auxiliary path, (just in case), particularly checking the capacitor for short circuit along the way.
--
Tony Williams.

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snipped-for-privacy@gmail.com says...

I had exactly this with a White Knight dryer. It was indeed the motor run (not motor start, apparently that's a different sort of motor) capacitor. I took it off (the big silver cylinder on top of the motor) and took it to a local motor rewinders where the bloke rummaged in a pile for a while and gave me a spare for a couple of quid.
That was ages ago and it's still running.
--
Roland Butter :- There\'s nothing like a knob of butter.

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