Going to attempt to change the capacitor on my tumble dryer... Its a 8
micro-Farad one.

I think its dead anyway but I'm assuming I can check with a multimeter?
What sort of voltage/current is one of these likely to have?

Assuming it is still ' live' how do I discharge it to make it safe?

paulfoel wrote:
Going to attempt to change the capacitor on my tumble dryer... Its a 8
micro-Farad one.

I think its dead anyway but I'm assuming I can check with a
multimeter? What sort of voltage/current is one of these likely to
have?

Assuming it is still ' live' how do I discharge it to make it safe?

Does your meter support capacitance? if not you're wasting you're time,
these are only a few pence anyway in a maplins outlet.

--
Sir Benjamin Middlethwaite

In article .com,
"paulfoel" writes:
Going to attempt to change the capacitor on my tumble dryer... Its a 8
micro-Farad one.

I think its dead anyway but I'm assuming I can check with a multimeter?
What sort of voltage/current is one of these likely to have?

Assuming it is still ' live' how do I discharge it to make it safe?

Most likely it is discharged through the motor windings unless
the switching is such that it gets disconnected, although
relying on the motor windings being intact is not smart when
the thing is known not to be working properly. Secondly, it
probably has a bleed resistor built in, although those can
fail too. I would probably just short it out with a screwdriver,
although that can in theory damage the capacitor. Leave it for
at least 5 minutes since last powered up, and then short out,
and you'll be fine. Making up a proper resistive discharger for
this one occasion just isn't worth it.

--
Andrew Gabriel

fail too. I would probably just short it out with a screwdriver,
although that can in theory damage the capacitor. Leave it for
at least 5 minutes since last powered up, and then short out,
and you'll be fine. Making up a proper resistive discharger for
this one occasion just isn't worth it.

--
Andrew Gabriel

I was in the local Maplin shop the other day and saw that you can purchase 1
farad (huge) capacitors for power supply smoothing chav's in car audio
systems.

Must be interesting when you accidently short one of these!

http://search.ebay.co.uk/search/1-fa...QQfclZ4QQfnuZ1


David

"paulfoel" wrote in message
oups.com...
Going to attempt to change the capacitor on my tumble dryer... Its a 8
micro-Farad one.

I think its dead anyway but I'm assuming I can check with a multimeter?
What sort of voltage/current is one of these likely to have?

Assuming it is still ' live' how do I discharge it to make it safe?


Does the motor have brushes and a commutator? If so, change the brushes
before you start looking elsewhere, they're seldom expensive and are a
consumable item. Capacitors may or may not last the life of an appliance but
brushes are certain to wear from day one and are usually the first suspect
in a misfiring/intermittant motor.

With brush type motors, the brushes wear down and consequently less pressure
is applied by the spring, causing a higher resistance/poorer connection
between brush and commutator. An arc is caused, which heats the brush and
can deform the casing causing the brush to stick, making the problem
increase exponentially. It also causes the commutator to become blackened
which makes matters even worse.

I'd take out the brush carriers and check the brushes move freely and that
there's plenty of length left on them. Also check the commutator is clean.

If the motor does not have a brush/commutator arrangement, I'd check all
connections are secure and check the control board for dry/cracked solder
joints before suspecting component failure.

Dave

"vortex2" wrote in message
.. .


Must be interesting when you accidently short one of these!


Nah - that's nancy stuff for kids

..... real man stuff here!

http://www.amasci.com/amateur/capexpt.html

On 21 Dec 2005 04:23:18 -0800, "paulfoel"
wrote:

Assuming it is still ' live' how do I discharge it to make it safe?

Stick a big screwdriver across it. This is bad advice for capacitors in
general, but for these motor capacitors used on 240V AC only it's OK.
There is minimal likelihood of there being any charge left in there,
you're only shorting it to make _sure_ before you touch it by hand. If
it _had_ been charged up by the Workshop Pixies beforehand, then it just
costs you a screwdriver and a pair of trousers.

If you're fooling with HT DC on capacitors, then fit proper bleed
resistors before you start and make yourself a discharging stick with a
resistor in it.

"Dave D" wrote in message
...

"paulfoel" wrote in message
oups.com...
Going to attempt to change the capacitor on my tumble dryer... Its a 8
micro-Farad one.

I think its dead anyway but I'm assuming I can check with a multimeter?
What sort of voltage/current is one of these likely to have?

Assuming it is still ' live' how do I discharge it to make it safe?


Does the motor have brushes and a commutator? If so, change the brushes
before you start looking elsewhere, they're seldom expensive and are a
consumable item. Capacitors may or may not last the life of an appliance
but brushes are certain to wear from day one and are usually the first
suspect in a misfiring/intermittant motor.

With brush type motors, the brushes wear down and consequently less
pressure is applied by the spring, causing a higher resistance/poorer
connection between brush and commutator. An arc is caused, which heats the
brush and can deform the casing causing the brush to stick, making the
problem increase exponentially. It also causes the commutator to become
blackened which makes matters even worse.

I'd take out the brush carriers and check the brushes move freely and that
there's plenty of length left on them. Also check the commutator is clean.

If the motor does not have a brush/commutator arrangement, I'd check all
connections are secure and check the control board for dry/cracked solder
joints before suspecting component failure.

Dave
nonsense it is clearly an induction motor.

Or how about this :-

http://www.electricstuff.co.uk/marxthree.html

"powerstation" wrote in message
...


Dave
nonsense it is clearly an induction motor.


Probably, but I'm not at the OP's house to take a look and be certain this
is the case, and as the symptoms are classic signs of worn brushes, I
thought I'd mention it in case.

The rest of my advice about looking for bad connections before replacing
components is perfectly valid as well.

Dave

"vortex2" writes:

fail too. I would probably just short it out with a screwdriver,
although that can in theory damage the capacitor. Leave it for
at least 5 minutes since last powered up, and then short out,
and you'll be fine. Making up a proper resistive discharger for
this one occasion just isn't worth it.

--
Andrew Gabriel

I was in the local Maplin shop the other day and saw that you can purchase 1
farad (huge) capacitors for power supply smoothing chav's in car audio
systems.

Must be interesting when you accidently short one of these!

http://search.ebay.co.uk/search/1-fa...QQfclZ4QQfnuZ1

A capacitor with a digital readout? Now they've gone over the top!

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.

powerstation wrote:

"Dave D" wrote in message
...

"paulfoel" wrote in message
oups.com...
Going to attempt to change the capacitor on my tumble dryer... Its a 8
micro-Farad one.

I think its dead anyway but I'm assuming I can check with a multimeter?
What sort of voltage/current is one of these likely to have?

Assuming it is still ' live' how do I discharge it to make it safe?


Does the motor have brushes and a commutator? If so, change the brushes
before you start looking elsewhere, they're seldom expensive and are a
consumable item. Capacitors may or may not last the life of an appliance
but brushes are certain to wear from day one and are usually the first
suspect in a misfiring/intermittant motor.

With brush type motors, the brushes wear down and consequently less
pressure is applied by the spring, causing a higher resistance/poorer
connection between brush and commutator. An arc is caused, which heats the
brush and can deform the casing causing the brush to stick, making the
problem increase exponentially. It also causes the commutator to become
blackened which makes matters even worse.

I'd take out the brush carriers and check the brushes move freely and that
there's plenty of length left on them. Also check the commutator is clean.

If the motor does not have a brush/commutator arrangement, I'd check all
connections are secure and check the control board for dry/cracked solder
joints before suspecting component failure.

Dave
nonsense it is clearly an induction motor.

Yep. It is.

Going to attempt to change the capacitor on my tumble dryer... Its a 8
micro-Farad one.

I think its dead anyway but I'm assuming I can check with a
multimeter?
What sort of voltage/current is one of these likely to have?

Assuming it is still ' live' how do I discharge it to make it safe?


Does the motor have brushes and a commutator? If so, change the brushes
before you start looking elsewhere, they're seldom expensive and are a
consumable item. Capacitors may or may not last the life of an
appliance
but brushes are certain to wear from day one and are usually the first
suspect in a misfiring/intermittant motor.

With brush type motors, the brushes wear down and consequently less
pressure is applied by the spring, causing a higher resistance/poorer
connection between brush and commutator. An arc is caused, which heats
the
brush and can deform the casing causing the brush to stick, making the
problem increase exponentially. It also causes the commutator to become
blackened which makes matters even worse.

I'd take out the brush carriers and check the brushes move freely and
that
there's plenty of length left on them. Also check the commutator is
clean.

If the motor does not have a brush/commutator arrangement, I'd check
all
connections are secure and check the control board for dry/cracked
solder
joints before suspecting component failure.

Dave
nonsense it is clearly an induction motor.

Yep. It is.

There is a TB regarding capacitors on White Knight TD's, the fault is caused
by the capacitor being affixed too close to the motor, the spare part now
includes a bracket to move it further away. Sometimes even when the part is
replaced the motor subsequently burns out if the windings have been damaged
by a stalled motor.

On Wed, 21 Dec 2005 15:09:16 -0000, "Dave D" wrote:

Probably, but I'm not at the OP's house to take a look and be certain this
is the case, and as the symptoms are classic signs of worn brushes, I
thought I'd mention it in case.

How many tumble driers use brushed motors?

How many brushed motors also have a capacitor?

Now this assumes that it _is_ a capacitor of course. If it does have a
brushed motor, I wouldn't be surprised if it had a line filter instead
and these can look very similar to capacitors.

vortex2 wrote:

fail too. I would probably just short it out with a screwdriver,
although that can in theory damage the capacitor. Leave it for
at least 5 minutes since last powered up, and then short out,
and you'll be fine. Making up a proper resistive discharger for
this one occasion just isn't worth it.

--
Andrew Gabriel


I was in the local Maplin shop the other day and saw that you can purchase 1
farad (huge) capacitors for power supply smoothing chav's in car audio
systems.

Must be interesting when you accidently short one of these!

http://search.ebay.co.uk/search/1-fa...QQfclZ4QQfnuZ1


David




Does anybody worry about the inrush current to these, and what that does
to one's alternator?

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

CJT wrote:
vortex2 wrote:

fail too. I would probably just short it out with a screwdriver,
although that can in theory damage the capacitor. Leave it for
at least 5 minutes since last powered up, and then short out,
and you'll be fine. Making up a proper resistive discharger for
this one occasion just isn't worth it.

--
Andrew Gabriel



I was in the local Maplin shop the other day and saw that you can
purchase 1 farad (huge) capacitors for power supply smoothing chav's
in car audio systems.

Must be interesting when you accidently short one of these!

http://search.ebay.co.uk/search/1-fa...QQfclZ4QQfnuZ1


David




Does anybody worry about the inrush current to these, and what that does
to one's alternator?

No.

Car wiring is radial from the battery to alternator and from the battery
to load. The impedance of the battery is much lower than that of the
alternator radial circuit - thus transient currents will be met almost
entirely by the battery.

You may like to think what effect the starter motor has on the alternator.

Also, the energy stored in a capacitor depends on the capacitance and on
the square of the voltage. Rather than have a 1F capacitor on the 12v
line, it would be much better to go to the higher voltage power rails of
the amplifier and stick beefy capacitors there.


--
Sue

nonsense it is clearly an induction motor.




Why do you say that? Most European washing machines use series wound
universal motors with carbon brushes. I've got a Creda washer sitting in
my basement right now awaiting arrival of a set of brushes amoung other
things, no idea how it ended up on this side of the pond but it's a cool
little machine.

http://search.ebay.co.uk/search/1-fa...QQfclZ4QQfnuZ1


A capacitor with a digital readout? Now they've gone over the top!


They went over the top years ago, those capacitors have been available
for a while.

Just try to find a car CD player anymore that looks at home in anything
but a gaudy racer boy Japenese compact. Seems like they're all fugly and
bubbly, loaded with useless distracting blinky lights and buttons so
small and jumbled it's impossible to operate them safely while driving.

Palindr˜»me wrote:
CJT wrote:

vortex2 wrote:

fail too. I would probably just short it out with a screwdriver,
although that can in theory damage the capacitor. Leave it for
at least 5 minutes since last powered up, and then short out,
and you'll be fine. Making up a proper resistive discharger for
this one occasion just isn't worth it.

--
Andrew Gabriel




I was in the local Maplin shop the other day and saw that you can
purchase 1 farad (huge) capacitors for power supply smoothing chav's
in car audio systems.

Must be interesting when you accidently short one of these!

http://search.ebay.co.uk/search/1-fa...QQfclZ4QQfnuZ1


David




Does anybody worry about the inrush current to these, and what that does
to one's alternator?

No.

Car wiring is radial from the battery to alternator and from the battery
to load. The impedance of the battery is much lower than that of the
alternator radial circuit - thus transient currents will be met almost
entirely by the battery.

You may like to think what effect the starter motor has on the alternator.



While this is true, don't forget that the starter motor will never be
operating under load while the alternator is producing any current
unless you're jump starting another car.

On Wed, 21 Dec 2005 19:56:57 UTC, James Sweet
wrote:

nonsense it is clearly an induction motor.

Why do you say that? Most European washing machines use series wound
universal motors with carbon brushes.

But we were talking about a dryer. They seem to use induction motors
(well, mine does).

--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
Avenue Supplies, http://avenuesupplies.co.uk

"James Sweet" wrote in message
news:dsiqf.694$2B5.463@trnddc01...


nonsense it is clearly an induction motor.


Why do you say that? Most European washing machines use series wound
universal motors with carbon brushes. I've got a Creda washer sitting in
my basement right now awaiting arrival of a set of brushes amoung other
things, no idea how it ended up on this side of the pond but it's a cool
little machine.

But its NOT a washing machine he's fixing ! its a tumble drier

nonsense it is clearly an induction motor.

Why do you say that? Most European washing machines use series wound
universal motors with carbon brushes.

But we were talking about a dryer. They seem to use induction motors
(well, mine does).

All the ones I have ever seen are, because they revolve the drum slowly, a
washing machine needs to spin at high speed

On Wed, 21 Dec 2005 19:59:50 GMT, James Sweet wrote:

http://search.ebay.co.uk/search/1-fa...QQfclZ4QQfnuZ1

A capacitor with a digital readout? Now they've gone over the top!


They went over the top years ago, those capacitors have been available
for a while.

Just try to find a car CD player anymore that looks at home in anything
but a gaudy racer boy Japenese compact. Seems like they're all fugly and
bubbly, loaded with useless distracting blinky lights and buttons so
small and jumbled it's impossible to operate them safely while driving.

Thats because youy get a really good one bult nto any car that chavs don't
buy.

In article dsiqf.694$2B5.463@trnddc01,
James Sweet writes:
Why do you say that? Most European washing machines use series wound
universal motors with carbon brushes. I've got a Creda washer sitting in
my basement right now awaiting arrival of a set of brushes amoung other
things, no idea how it ended up on this side of the pond but it's a cool
little machine.

A European washing machine operates its motor at a large
number of different speeds (and even gradually vary the
speed in some cases) throughout various stages of the
wash cycle, and depending on the wash program selected.
This is most easily done with a universal motor combined
with an electronic speed control board and servo feedback.
(It used to be done with an induction motor and solenoid
operated gearbox 40 years ago, but that's more expensive
and a lot less flexible.)

Tumble driers only have to be able to reverse the drum,
but don't need to change the speed. For this simpler
requirement, an induction motor tends to win.

--
Andrew Gabriel

On Wed, 21 Dec 2005 18:37:10 GMT, CJT wrote:

vortex2 wrote:

fail too. I would probably just short it out with a screwdriver,
although that can in theory damage the capacitor. Leave it for
at least 5 minutes since last powered up, and then short out,
and you'll be fine. Making up a proper resistive discharger for
this one occasion just isn't worth it.

--
Andrew Gabriel

I was in the local Maplin shop the other day and saw that you can purchase 1
farad (huge) capacitors for power supply smoothing chav's in car audio
systems.

Must be interesting when you accidently short one of these!

http://search.ebay.co.uk/search/1-fa...QQfclZ4QQfnuZ1

David



Does anybody worry about the inrush current to these, and what that does
to one's alternator?

its nowhere as bad as what a statrter motor does...alternators are limited
anyway.

Bob Eager wrote:
On Wed, 21 Dec 2005 19:56:57 UTC, James Sweet
wrote:


nonsense it is clearly an induction motor.


Why do you say that? Most European washing machines use series wound
universal motors with carbon brushes.


But we were talking about a dryer. They seem to use induction motors
(well, mine does).



Yeah somehow I missed that we were discussing a dryer. The matching
Creda dryer does in fact have an induction motor in it, weird to see a
clothes dryer that will plug into a 15A 240v receptacle, US dryers are
almost universally 4KW.

Tumble driers only have to be able to reverse the drum,
but don't need to change the speed. For this simpler
requirement, an induction motor tends to win.



Why do they have to be able to reverse the drum? I've never seen a dryer
that did that, obviously they must exist but I'm not sure of the benefits.

Thats because youy get a really good one bult nto any car that chavs don't
buy.


Would be nice, but I'm afraid back in '84, '87 and '88 respectively,
cars didn't come with CD players of any sort, hence my need to install
aftermarket units in mine.


Not to mention I'm still not aware of any OEM units that will play MP3
discs, an essential feature to me that made all earlier CD players
virtually obsolete. 10 hours of music on one disc, no more fumbling with
CD's in traffic.

On Wed, 21 Dec 2005 20:34:49 UTC, James Sweet
wrote:

Why do they have to be able to reverse the drum? I've never seen a dryer
that did that, obviously they must exist but I'm not sure of the benefits.

Loads of them do it[1]...helps to untangle the clothes.

[1] except in the backwards USA?
--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
Avenue Supplies, http://avenuesupplies.co.uk

In message .com,
paulfoel writes
Going to attempt to change the capacitor on my tumble dryer... Its a 8
micro-Farad one.

I think its dead anyway but I'm assuming I can check with a multimeter?
What sort of voltage/current is one of these likely to have?

Assuming it is still ' live' how do I discharge it to make it safe?

It depends what's across it,

stick a screwdriver across it - that'll discharge it

--
geoff

In message , Slurp
writes
Nah - that's nancy stuff for kids

.... real man stuff here!

http://www.amasci.com/amateur/capexpt.html


Where does one start, any site that had the following in the disclaimer

'DISCLAIMER: the experiments described below are fantastically
dangerous, and they are described without reference to the
many precautions needed to guarantee the experimenter's safety.
Accidentally discharging these capacitor banks through your
body can not only kill, but can explode flesh and bone.'

Followed by

'PARENTS: I supply no detailed plans for reproducing these
experiments. Also, these experiments require large and
expensive lab equipment which is not obtainable by children.
(And the plans for an atomic bomb are safe for children too,
because kids can't afford to buy kilograms of Plutonium!)
If your kids have access to 5,000 volt high-current power supplies,
then they are already in great danger, whether or not they read
about my capacitor discharge experiments below.'

Has my respect!
--
Andrew Sinclair http://www.smellycat.org

In message .com,
writes
Or how about this :-

http://www.electricstuff.co.uk/marxthree.html


STOP IT STOP IT STOP IT

You're giving me ideas

--
geoff

In uk.d-i-y powerstation wrote:

If the motor does not have a brush/commutator arrangement, I'd check all
connections are secure and check the control board for dry/cracked solder
joints before suspecting component failure.

Dave
nonsense it is clearly an induction motor.

According to my Electrical Engineering professor at university *all*
electrical machines (including transoformers) are really induction
motors.

--
Chris Green

wrote in message ...
In uk.d-i-y powerstation wrote:

If the motor does not have a brush/commutator arrangement, I'd check
all
connections are secure and check the control board for dry/cracked
solder
joints before suspecting component failure.

Dave
nonsense it is clearly an induction motor.

According to my Electrical Engineering professor at university *all*
electrical machines (including transoformers) are really induction
motors.

--
Chris Green

Motors with squirrel-cage rotors can be used on single-phase alternating
current by means of various arrangements of inductance and capacitance that
alter the characteristics of the single-phase voltage and make it resemble a
two-phase voltage. Such motors are called split-phase motors or condenser
motors (or capacitor motors), depending on the arrangement used.
Single-phase squirrel-cage motors do not have a large starting torque, and
for applications where such torque is required, repulsion-induction motors
are used. A repulsion-induction motor may be of the split-phase or condenser
type, but has a manual or automatic switch that allows current to flow
between brushes on the commutator when the motor is starting, and
short-circuits all commutator segments after the motor reaches a critical
speed. Repulsion-induction motors are so named because their starting torque
depends on the repulsion between the rotor and the stator, and their torque
while running depends on induction. Series-wound motors with commutators,
which will operate on direct or alternating current, are called universal
motors. They are usually made only in small sizes and are commonly used in
household appliances.

Andy Dingley wrote:

How many tumble driers use brushed motors?

I don't know, never had one apart, but I assumed they all did. Every
washing machine I've ever repaired had a brush motor, why would they use
induction on a tumble fryer as a matter of interest?

Dave

Andy Dingley wrote:

On Wed, 21 Dec 2005 15:09:16 -0000, "Dave D" wrote:

Probably, but I'm not at the OP's house to take a look and be certain this
is the case, and as the symptoms are classic signs of worn brushes, I
thought I'd mention it in case.

How many tumble driers use brushed motors?

How many brushed motors also have a capacitor?

Now this assumes that it _is_ a capacitor of course. If it does have a
brushed motor, I wouldn't be surprised if it had a line filter instead
and these can look very similar to capacitors.

Nope. Definitely an 8 micro-Farad capacitor.

There is a TB regarding capacitors on White Knight TD's, the fault is caused
by the capacitor being affixed too close to the motor, the spare part now
includes a bracket to move it further away. Sometimes even when the part is
replaced the motor subsequently burns out if the windings have been damaged
by a stalled motor.

TB ? (Technical Brief?)

Where can I see this info?

"paulfoel" wrote in message
ups.com...
There is a TB regarding capacitors on White Knight TD's, the fault is
caused
by the capacitor being affixed too close to the motor, the spare part now
includes a bracket to move it further away. Sometimes even when the part
is
replaced the motor subsequently burns out if the windings have been
damaged
by a stalled motor.

TB ? (Technical Brief?)

Where can I see this info?

Sent to your email if it genuine
Peter

On Thu, 22 Dec 2005 10:12:06 GMT, "david lang"
wrote:

I don't know, never had one apart, but I assumed they all did. Every
washing machine I've ever repaired had a brush motor, why would they use
induction on a tumble fryer as a matter of interest?

You use induction motors whenever you can - they're quieter (this is a
domestic appliance after all) and they're cheaper. The advantage of the
brushed motor is that they have much higher torque at low speeds or when
stalled (why they appear on power tools) and they're also more easily
controllable for variable speeds etc. There's a lot of things a washing
machine does that a tumble drier just doesn't need.

In article ,
david lang wrote:

Andy Dingley wrote:
How many tumble driers use brushed motors?

I don't know, never had one apart, but I assumed they all did.
Every washing machine I've ever repaired had a brush motor, why
would they use induction on a tumble fryer as a matter of
interest?

Relatively constant speed operation under variable load,
without the expense of speed-sensor and controller?

--
Tony Williams.