Can washing machine start capacitor test good - and still be bad?

[Home Guy]

About a year ago the motor in my kenmore washing machine was acting up -
buzzing but not turning. I suspected the start capacitor and picked up
a used one for $10 at a local repair shop. These are black, about the
size of a D-cell battery.

The original was 270 - 324 mfd, 110 vac. Model 3348058.

The one I got as a replacement was 189 - 227 mfd, 357021.

Even though I had a capacitance meter at work, I just went out and
picked up the used cap, installed it and bingo - the washing machine
works. That was a year ago.

So more recently, over the past week or two, the motor was acting up
again. It would buzz, I'd bump the machine, and it would start. But
yesterday even bumping / rocking the machine didn't work.

So I took the capacitor out and measured the original and this
replacement. The original measured 298 mdf (micro-farad) and the
replacement was 211. Both numbers pretty much exactly what they should
be according to their labels.

So maybe the problem wasn't / isin't the capacitor - but a centrifugal
contact in the motor? Do these motors have such contacts (start
winding) ?

Or can hand-held digital capacitance meters perform correct measurements
on these big caps?

I'm cross-posting this to alt.hvac, because my question about this
washing machine motor capacitor and how well or accurately a capacitance
meter can measure them if they're bad might also apply to compressor or
fan motors.

As far as I can tell, there is just this one capacitor connected to this
motor, so I don't think there are separate start and run capacitors.

[Tony Hwang]

Hi,
Rule of thumb, you don't replace cap. with lesser value. If same one is
not available, use one with larger value. Even tho meter shows it OK,
under voltage in circuit it can go bad.

[Home Guy]

Tony Hwang wrote:

> Hi,
> Rule of thumb, you don't replace cap. with lesser value. If same one
> is not available, use one with larger value. Even tho meter shows it
> OK, under voltage in circuit it can go bad.

But why could I get the motor to start by bumping the machine?

Are there centrifugal contacts in the motor?

Or was the bump enough to get the spindle turning?

[hrho...@sbcglobal.net]

I would suspect the starting motor contacts equally likely with the starting capacitor. The mfd value of the replacement capacitor you bought a year ago is apppreciably less than the mfd of the original capacitor, and that would make the starting torque less than the original design. Then, if things get marginal/sticky, the motor might not be able to have enough torques to start. Shaking the machine could provide just enough oompf to get things moving. I would buy the correct value capacitor and try that. At $15 bucks or so, it is much easier than to take things apart to get to the starting contacts on the motor.

[Tony Hwang]

Hi,
You're doing the job of the cap.(shifting(leading) current phase)
Motor winding is inductive, with cap. you counter the inductance.
That cap. is called PSC(Phase shift capacitor). Most new appliance,
even garage door opener, vacuum cleaner, furnace blower, nowadays use
smaller more powerful DC motors. DC motor's efficiency is higher than
AC motor using PSC. Also Diesel electric locomotive propulsion is
by DC motor. Diesel engine drives generator, which in turn it drives
DC motor. That is why it is called Diesel electric locomotive.

[Tony Hwang]

hrho...@sbcglobal.net wrote:
> I would suspect the starting motor contacts equally likely with the starting capacitor. The mfd value of the replacement capacitor you bought a year ago is apppreciably less than the mfd of the original capacitor, and that would make the starting torque less than the original design. Then, if things get marginal/sticky, the motor might not be able to have enough torques to start. Shaking the machine could provide just enough oompf to get things moving. I would buy the correct value capacitor and try that. At $15 bucks or so, it is much easier than to take things apart to get to the starting contacts on the motor.
>

Hi,
I was surprised to hear OP bought used cap. I'd never do that.

[philo]

On 03/03/2014 03:28 PM, Home Guy wrote:
> About a year ago the motor in my kenmore washing machine was acting up -
> buzzing but not turning. I suspected the start capacitor and picked up
> a used one for $10 at a local repair shop. These are black, about the
> size of a D-cell battery.
>
> The original was 270 - 324 mfd, 110 vac. Model 3348058.
>
> The one I got as a replacement was 189 - 227 mfd, 357021.
>
> Even though I had a capacitance meter at work, I just went out and
> picked up the used cap, installed it and bingo - the washing machine
> works. That was a year ago.

Motor start capacitors are internally fused ...occasionally the link can
break but the contacts still touch and will measure OK...but not work
under load.


I worked on industrial equipment for 38 years that had such capacitors
in them...but it's a condition I've only seen a few times.

[micky]

On Mon, 03 Mar 2014 16:28:49 -0500, Home Guy <"Home"@Guy. com> wrote:

>
>So more recently, over the past week or two, the motor was acting up
>again. It would buzz, I'd bump the machine, and it would start.

Are you sure it wasn't running all the time, but the belt was slipping.
That can sound like a hum too iirc.

Before I tightened it, I would give the edge of the drum a shove and
that would start it on the spin cycle. (I think it's a sub-cycle
really. Why is it called a cycle?)

On my Whirlpool I have to tighten the belt every 30 years, but some
belts might loosen more quickly.

[Home Guy]

Tony Hwang wrote:

> I was surprised to hear OP bought used cap. I'd never do that.

Locally, the price of a new cap is around $60. There's no internet
source that after customs/brokerage charges I'm going to get this new
for under $30.

So here's what I've done so far:

Connect both caps in parallel and the meter reads 500 mfd - which is
expected. The original was 300 and the replacement was 200.

Connect both up to the motor - and the machine works (drum turns) when
machine is set to spin cycle. Motor hums (drum doesn't turn) when
machine is set to agitate.

Remove the 200 mfd cap and just connect the original 300 mfd - and get
same result. Spin works, agitate hums.

Swap the caps so that only the 200 mfd is connected, and motor hums with
spin and agitate.

This is with an empty drum. The problem arose while the drum was full
of water, about to start a spin cycle (with the 200 mfd cap).

So are these caps so weak that even combined they don't have the energy
to turn an empty drum set to agitate?

Or is agitate using different windings of the motor, and something else
is going on?

micky wrote:

> Are you sure it wasn't running all the time, but the belt was
> slipping.

There's no belt in this washing machine. It's direct-drive.

Maybe you're thinking of a dryer.

[philo]

On 03/03/2014 07:10 PM, Home Guy wrote:
> Tony Hwang wrote:
>
>> I was surprised to hear OP bought used cap. I'd never do that.
>
> Locally, the price of a new cap is around $60. There's no internet
> source that after customs/brokerage charges I'm going to get this new
> for under $30.
>
> S

That price is way out of line ...don't buy it.


Test your capacitor by wiring it in series with a light bulb (100 watt
incandescent)


If it lights, the capacitor is ok

[hrho...@sbcglobal.net]

On Monday, March 3, 2014 3:28:49 PM UTC-6, Home Guy wrote:
Does the cycle difference spin vs wash)depend on the direction of motor rotation? It's been 20+ years since I worked on a Kenmore washing machine.

[Home Guy]

philo wrote:

> Test your capacitor by wiring it in series with a light bulb
> (100 watt incandescent)
>
> If it lights, the capacitor is ok

Ok, I didn't do that (but would have if the following didn't work).

Turns out that you have to have water in the drum for the agitate to
work.

To make a long story short, I had to hook up both capacitors in parallel
to get the washer to function for all settings and cycles and get no
motor buzzing or stalling.

These are complicated motors with lots of wires, and I thought I was
going to have to dick around with it as in this thread:

http://www.applianceblog.com/mainforums/threads/
35555-Top-Load-Kenmore-WON-T-Agitate-but-WILL-spin-and-pump-Motor-hums-when-it-should-agitate

So I'm using short wires with alligator clips to connect the
capacitors. Tommorrow I'm going to solder them together and finish the
repair.

I'm glad I didn't throw away the original capacitor, and extra glad I
was able to find it...

[hrho...@sbcglobal.net]

Ok - So it looks like using the two capacitors in parallel is increasing the starting torque of the motor and all is well(for now). But something is/was/has changed and I wouldn't feel too comfortable.

[nestork]

Home Guy:

If bumping the washer caused it to work properly, I expect your
capacitors are OK, but the connections are dirty. I don't believe you
have a slipping belt. If you did, your laundry room would be full of
smoke and you'd smell burning rubber.

I expect you can find the correct capacitor online for under $10. You
may have to import it from the States, but that's no big deal, I import
stuff all the time and I can tell you how to fill out the Canadian
Border Services B3 form, and the procedure to follow to get it across
the border. However, keep in mind that even a $10 item will cost $10 to
20 in shipping costs.

The easiest way to understand how a start capacitor works is to
understand that there's no such thing as capacitor start or split phase
electric motors that use 3 phase electric power. With three phase
electric power you simply arrange the poles around the stator 120
degrees apart and you create a rotating magnetic field.

With 120 volt single phase power, you can normally only create an
oscillating magnetic field. To create a rotating magnetic field, you
have to use some kind of trick to create a rotating magnetic field for
the rotor to follow.

The way this is done with a capacitor start motor is to have two
identical windings wired in parallel and arranged at a 90 degree spacing
around the stator. So you have North pole of winding 1, South pole of
Winding 2, South pole of Winding 1 and North pole of winding 2 all
spaced 90 degrees from each other around the stator.

Now, we simply wire a capacitor in series with ONE of those windings.

With a resistor, the current is highest when the AC voltage sine wave is
highest, and the current is instantaneously zero when the applied AC
voltage sine wave is zero.

With a capacitor in series with the start winding, things are totally
different. With a capacitor, the current out of the capacitor (and
hence through the start winding) is highest when the RATE OF CHANGE IN
VOLTAGE of the applied voltage sine wave is highest, and that occurs on
the applied sine wave when the instantaneous voltage is ZERO volts.
That is when the voltage is changing from a positive voltage to a
negative voltage and vice versa. That's 90 degrees out of phase with
the winding that doesn't have a capacitor.

Similarily, with a capacitor in the start winding, the current out of
the capacitor (and hence through the start winding) is at a minimum when
the applied voltage sine wave is at a maximum or a minimum. That is
when one plate of the capacitor is fully energized and the voltage on it
is starting to drop, the instantaneous current out of the capacitor will
be zero. That's 90 degrees out of phase with the winding that doesn't
have a capacitor.

Consequently with the start and run winding wired in parallel, the
capacitor in the start winding will have it's current sine wave 90
degrees out of phase with the run winding, and as a result, the magnetic
field of the start winding occurs 90 degrees sooner or later than the
run winding. And, that's true even though both windings have the same
voltage sine wave applied to them.

So, the capacitance of the capacitor you use is important. You can just
take one from one motor and use it in another.

There is also another kind of induction motor that doesn't use a
capacitor. Instead, in a "split phase" motor, winding #1 will be made
with a small number of coils of thick copper wire, and winding #2 will
be made with a large number of coils of thin copper wire. Because of
the difference in resistance of these coils, they have different
resulting impedances, and that results in one coil developing it's
magnetic field earlier than the other, and that's what creates the
illusion of a rotating magnetic field for the rotor to follow.

In both capacitor start motors and split phase motors, the motor is
perfectly happy to turn in the reverse direction if you simply reverse
the polarity of one of the windings. So, if you switch the wires going
to Winding #1, the motor will start with the same torque, and it'll
reach the same operating speed, only it'll be turning backwards. Never
reverse the polarity of both windings in an induction motor. That will
cause a singularity in the space time continuum with the result that you
finish doing the switch before you began, and hence the motor turns in
it's original direction again.

Maytag washing machines have a reversing relay that automatically
switches the wires going to the run winding. That relay is controlled
by the timer, and it reverses the terminals to the run winding so that
the motor spins in one direction during the wash cycle (where the
agitator oscillates) and in the reverse direction during the spin cycles
(where the wash basket spins). Most washing machines use this
reversible characteristic of induction motors to reverse the direction
of rotation of the motor from the wash cycle to the spin cycle. In
Maytag's case the motor turns a belt that causes a pulley to rotate up
or down a helical shaft. When the pully rides up the shaft it engages
clutches in the transmission that lock the transmission up so that the
spinning of the pully directly results in the spinning of the wash
basket. And, when the motor reverses direction, that pulley turns the
opposite way and rides down the helical shaft to unlock the transmission
and allow the rotation of the pulley to cause the oscillation of the
agitator.

In a case like this, I think your best bet is to got to a factory
authorized Kenmore repair depot to buy your parts. It's true that
you'll pay more for each part, but you also get all the expert technical
support tossed in free of charge. So, you spend a bit more on parts,
but you save all the labour by doing it yourself under the tuteledge of
a Kenmore appliance repairman.




--
nestork

[Tony Hwang]

hrho...@sbcglobal.net wrote:
> Ok - So it looks like using the two capacitors in parallel is increasing the starting torque of the motor and all is well(for now). But something is/was/has changed and I wouldn't feel too comfortable.
>

Hi,
Paralleling them creates a cap. value of sum of two.

[KLayt...@aol.com]

You can buy the exact replacement here:

http://www.hottubwarehouse.com/Motor-Start-Capacitor-270-324-MFD-PMJ270-p/bc-270.htm?gclid=CMXZ5oOj-LwCFYdgfgodHWQAmg

http://www.newark.com/cornell-dubilier/psu27015a/capacitor-alum-elec-270-324uf/dp/72K6679?mckv=sJAWZe4xc|pcrid|33870213381|plid|&CMP=KNC-GPLA

http://www.galco.com/buy/NTE-Electronics/MSC125V270

http://www.shop.clean-mart.net/Start-Capacitor-270-324-MFD-12112.htm

http://www.refrisource.com/index.php?page=shop.product_details&product_id=189&flypage=flypage.tpl&pop=0&vmcchk=1&option=com_virtuemart&Itemid=64

[philo]

Hope it stays working.

I have seen capacitors lose value too, but again that is very rare.


--- news://freenews.netfront.net/ - complaints: ne...@netfront.net ---

[Stormin Mormon]

Lets see if any math nerds out there: The
hippopotomus cap is the sum of the farads
of the other two hides.

Very obscure and dificult to follow
hints at a very old math joke.

--
.
Christopher A. Young
Learn about Jesus
www.lds.org
.

[Stormin Mormon]

On 3/3/2014 5:42 PM, Home Guy wrote:
>
> Or was the bump enough to get the spindle turning?
>

Probably that. Glad you got it running, though.

[Luke C Feur]

My American Standard had capacitor problems. The manufacturer reccommended a kickstart to retain enough jolt.

[micky]

On Tue, 4 Mar 2014 03:58:52 +0100, nestork
<nestork...@diybanter.com> wrote:

>
>Home Guy:
>
>If bumping the washer caused it to work properly, I expect your
>capacitors are OK, but the connections are dirty. I don't believe you
>have a slipping belt. If you did, your laundry room would be full of
>smoke and you'd smell burning rubber.

That makes a lot of sense, but somehow I never had any smoke or any
burning rubber smell. For a while, when it was time for the spin
cycle, I guess I would hear a noise and I would go there and push the
basket with my hand to get it started. Either that or I'd just go
check on the machine and find it stuck not yet having spun. I think
it often started the 2nd spin cycle on its own.

When that was getting less reliable, I tried to tighten the belt but did
a bad job. The basket still woulnd't start on its own, but I was able
to push start it again.

A few loads later, I got a jack handle from on old GM car and used that
as a better lever to tighten the belt and it's been fine for about 10 or
more loads now.

I don't understand it but one can't always assume theory is reality --
well maybe it somehow went quickly** from working well to having a belt
so loose it didn't rub, but still grabbed on when I pushed it!! --



and it will only take a minute or two to see if the motor really is not
turning.



Mine is a Sears Whirlpool fwiw. It always agitated properly and did
everything but spin. I was kidding about tightening it again in 30
years. I think some day I will need a new belt.

**I've been away for a couple months at a time. Maybe it loosened then.

[micky]

On Mon, 03 Mar 2014 20:10:21 -0500, Home Guy <"Home"@Guy. com> wrote:

>micky wrote:
>
>> Are you sure it wasn't running all the time, but the belt was
>> slipping.
>
>There's no belt in this washing machine. It's direct-drive.
>
>Maybe you're thinking of a dryer.

No, I was thinking of a washer. You didn't say before that it was
direct drive.