White Knight tumble dryer - drum not turning

[paulfoel]

Heater comes on no problem (so its not the thermal switch).

When I take belt off the motor does not turn until I give it a slight
nudge. If I put the belt back on I still cant get the drum to turn
(probably because I cant turn it fast enough to start the motor up).

Could this be the capacitor? I've heard that this type of motor uses
the capacitor to kick start the motor.

To be honest, it started happening but if you left it for 30 mins it
would then work OK (capacitor charging?). Now thought theres nothing.

My wife insists though that occasionally the dryer stopped half way
through. I know its a reverse action so I was wondering if this could
be explained by the motor needing to stop and then restart in the
opposite direction (using the capacitor).

Any ideas ?

 

[J B]

Any ideas ?

None at all ..... but the drum's knackered in ours (makes one hell of a
clunk on each revolution))
So if you're scrapping it .......

;-)

 

[Palindr☻me]

Heater comes on no problem (so its not the thermal switch).

When I take belt off the motor does not turn until I give it a slight
nudge. If I put the belt back on I still cant get the drum to turn
(probably because I cant turn it fast enough to start the motor up).

Could this be the capacitor? I've heard that this type of motor uses
the capacitor to kick start the motor.

To be honest, it started happening but if you left it for 30 mins it
would then work OK (capacitor charging?). Now thought theres nothing.

My wife insists though that occasionally the dryer stopped half way
through. I know its a reverse action so I was wondering if this could
be explained by the motor needing to stop and then restart in the
opposite direction (using the capacitor).

Any ideas ?

You might want to ask on a.e.electrical - as it is more an electrical
problem than electronics or diy.

I'm not sure what type of motor this machine has - but would go looking
for brush-holders and worn brushes. BICBW

 

[Andrew Gabriel]

Heater comes on no problem (so its not the thermal switch).

When I take belt off the motor does not turn until I give it a slight
nudge. If I put the belt back on I still cant get the drum to turn
(probably because I cant turn it fast enough to start the motor up).

Could this be the capacitor? I've heard that this type of motor uses
the capacitor to kick start the motor.

To be honest, it started happening but if you left it for 30 mins it
would then work OK (capacitor charging?). Now thought theres nothing.

My wife insists though that occasionally the dryer stopped half way
through. I know its a reverse action so I was wondering if this could
be explained by the motor needing to stop and then restart in the
opposite direction (using the capacitor).

Any ideas ?

The capacitor is easy to test. What rating is written on it?
Assuming it's a mains one, connect it in series with a mains
light bulb (something between 40W and 100W), and the light
should come on, but not as bright running directly off the
mains. Beware in case the capacitor case has become live in
some internal failure.

However, the nature of the fault you describe sounds to me
more like a broken motor winding. Capacitors don't usually
fail intermitently.

 

[paulfoel]

None at all ..... but the drum's knackered in ours (makes one hell of a
clunk on each revolution))
So if you're scrapping it .......

;-)

If I can't fix ours, you're quite welcome to the drum out of mine (if
you pay for the postage!)

 

[paulfoel]

The capacitor is easy to test. What rating is written on it?
Assuming it's a mains one, connect it in series with a mains
light bulb (something between 40W and 100W), and the light
should come on, but not as bright running directly off the
mains. Beware in case the capacitor case has become live in
some internal failure.

However, the nature of the fault you describe sounds to me
more like a broken motor winding. Capacitors don't usually
fail intermitently.

8 micro Farrad

 

[J B]

If I can't fix ours, you're quite welcome to the drum out of mine (if
you pay for the postage!)

Where are you?

 

[paulfoel]

Where are you?

Newport, S. Wales

 

[sPoNiX]

Heater comes on no problem (so its not the thermal switch).

When I take belt off the motor does not turn until I give it a slight
nudge. If I put the belt back on I still cant get the drum to turn
(probably because I cant turn it fast enough to start the motor up).

Could this be the capacitor? I've heard that this type of motor uses
the capacitor to kick start the motor.

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

 

[Andrew Gabriel]

8 micro Farrad

So that's an impedance of 398 ohms at 50Hz, so a 60W 240V lamp
in series should be around half brightness if the capacitor is
working. If it's not working, lamp will be fully on or fully
off (depending on the capacitor's failure mode).

If you need a new capacitor, one source would be an electrical
wholesaler, who will stock them as power factor correction
capacitors for fluorscent fittings and HID lamps.

Actually, just checked CPC catalogue, and there are a few
designated as motor run capacitors...
CA00003 @ £3.95 (metal case, 1/4" tabs),
CA00010 @ £3.35 (plastic case, 1/4" tabs),
CA00019 @ £3.65 (plastic case, flying leads).
All these are 8µF, 440VAC (which is fine for mains),
with a mounting stud on the base.

 

[paulfoel]

So that's an impedance of 398 ohms at 50Hz, so a 60W 240V lamp
in series should be around half brightness if the capacitor is
working. If it's not working, lamp will be fully on or fully
off (depending on the capacitor's failure mode).

If you need a new capacitor, one source would be an electrical
wholesaler, who will stock them as power factor correction
capacitors for fluorscent fittings and HID lamps.

Actually, just checked CPC catalogue, and there are a few
designated as motor run capacitors...
CA00003 @ £3.95 (metal case, 1/4" tabs),
CA00010 @ £3.35 (plastic case, 1/4" tabs),
CA00019 @ £3.65 (plastic case, flying leads).
All these are 8µF, 440VAC (which is fine for mains),
with a mounting stud on the base.

Whats the difference between a motor run and a motor start capacitor ?

 

[powerstation]

So that's an impedance of 398 ohms at 50Hz, so a 60W 240V lamp
in series should be around half brightness if the capacitor is
working. If it's not working, lamp will be fully on or fully
off (depending on the capacitor's failure mode).

If you need a new capacitor, one source would be an electrical
wholesaler, who will stock them as power factor correction
capacitors for fluorscent fittings and HID lamps.

Actually, just checked CPC catalogue, and there are a few
designated as motor run capacitors...
CA00003 @ £3.95 (metal case, 1/4" tabs),
CA00010 @ £3.35 (plastic case, 1/4" tabs),
CA00019 @ £3.65 (plastic case, flying leads).
All these are 8µF, 440VAC (which is fine for mains),
with a mounting stud on the base.

Whats the difference between a motor run and a motor start capacitor ?

None... the difference is the motor the capacitors are the same.

 

[Guest]

Heater comes on no problem (so its not the thermal switch).

When I take belt off the motor does not turn until I give it a slight
nudge. If I put the belt back on I still cant get the drum to turn
(probably because I cant turn it fast enough to start the motor up).

Could this be the capacitor? I've heard that this type of motor uses
the capacitor to kick start the motor.

To be honest, it started happening but if you left it for 30 mins it
would then work OK (capacitor charging?). Now thought theres nothing.

My wife insists though that occasionally the dryer stopped half way
through. I know its a reverse action so I was wondering if this could
be explained by the motor needing to stop and then restart in the
opposite direction (using the capacitor).

Any ideas ?

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.

 

[paulfoel]

Whats the difference between a motor run and a motor start capacitor ?

None... the difference is the motor the capacitors are the same.

Bugger. Just paid £12 inc delivery of £6 for a motor start capacitor
online. Could have got a motor run capacitor of the same for £4 in
maplins.

 

[powerstation]

Whats the difference between a motor run and a motor start capacitor ?

None... the difference is the motor the capacitors are the same.

Bugger. Just paid £12 inc delivery of £6 for a motor start capacitor
online. Could have got a motor run capacitor of the same for £4 in
maplins.

The White Knight is a run capacitor system i.e. the start and run windings
are both energized when the motor is running. A capacitor start motor is
usually much bigger and has a means of disconnecting the start winding and
capacitor once the motor is running, either by the starter or a centrifugal
switch.

 

[mf5055]

Heater comes on no problem (so its not the thermal switch).

When I take belt off the motor does not turn until I give it a slight
nudge. If I put the belt back on I still cant get the drum to turn
(probably because I cant turn it fast enough to start the motor up).

Could this be the capacitor? I've heard that this type of motor uses
the capacitor to kick start the motor.

To be honest, it started happening but if you left it for 30 mins it
would then work OK (capacitor charging?). Now thought theres nothing.

My wife insists though that occasionally the dryer stopped half way
through. I know its a reverse action so I was wondering if this could
be explained by the motor needing to stop and then restart in the
opposite direction (using the capacitor).

Any ideas ?

mf5055 when you take the belt off you have too turn the motor alittl
befor it works simple baad moto

 

[Ron(UK)]

Heater comes on no problem (so its not the thermal switch).

When I take belt off the motor does not turn until I give it a slight
nudge. If I put the belt back on I still cant get the drum to turn
(probably because I cant turn it fast enough to start the motor up).

Could this be the capacitor? I've heard that this type of motor uses
the capacitor to kick start the motor.

To be honest, it started happening but if you left it for 30 mins it
would then work OK (capacitor charging?). Now thought theres nothing.

My wife insists though that occasionally the dryer stopped half way
through. I know its a reverse action so I was wondering if this could
be explained by the motor needing to stop and then restart in the
opposite direction (using the capacitor).

Any ideas ?

Almost certainly the motor is faulty, probably starting windings failed,
but check the motor connector for poor or burnt contacts.

Ron(UK)

 

[James Sweet]

Heater comes on no problem (so its not the thermal switch).

When I take belt off the motor does not turn until I give it a slight
nudge. If I put the belt back on I still cant get the drum to turn
(probably because I cant turn it fast enough to start the motor up).

Could this be the capacitor? I've heard that this type of motor uses
the capacitor to kick start the motor.

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.

 

[James Sweet]

Whats the difference between a motor run and a motor start capacitor ?

None... the difference is the motor the capacitors are the same.

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.

 

[James Sweet]

The White Knight is a run capacitor system i.e. the start and run windings
are both energized when the motor is running. A capacitor start motor is
usually much bigger and has a means of disconnecting the start winding and
capacitor once the motor is running, either by the starter or a centrifugal
switch.

Ah, that's a PSC (permanent split capacitor) motor. Low starting torque
but simple, cheap, and generally reliable.