Washing machine motor won't start, bad triac ?

[Andre Majorel]

After reflowing everything on the controller board and reseating
the connectors it still won't work.

The motor of the washing machine spins for a few degrees and
stops. You can get it to spin (slowly) by pulling on the belt
but only in one direction ! Lots of sparks inside the motor.

The brushes are good and the motor seems mechanically fine.
I suspect the triac (ST BTB16 600CI). Plausible ?

Thanks in advance.

 

[Jeffrey Angus]

After reflowing everything on the controller board and reseating
the connectors it still won't work.

The motor of the washing machine spins for a few degrees and
stops. You can get it to spin (slowly) by pulling on the belt
but only in one direction ! Lots of sparks inside the motor.

The brushes are good and the motor seems mechanically fine.
I suspect the triac (ST BTB16 600CI). Plausible ?

Thanks in advance.

does the motor have a start capacitor and a centrifugal
speed switch to disconnect it?

Jeff

 

[Andre Majorel]

does the motor have a start capacitor and a centrifugal
speed switch to disconnect it?

I thought that was mutually exclusive with having brushes.

 

[PeterD]

After reflowing everything on the controller board and reseating
the connectors it still won't work.

The motor of the washing machine spins for a few degrees and
stops. You can get it to spin (slowly) by pulling on the belt
but only in one direction ! Lots of sparks inside the motor.

Lot's of sparks inside the motor doesn't sound like a bad triac to me.
Sounds like a bad motor.

 

[Jamie]

I thought that was mutually exclusive with having brushes.

I didn't know washing machines had brushed motors?

They do have variable speed controllers that do fail, along with
shorting the motor windings with them!



Jamie

 

[Jamie]

See video showing washing machine brushes and how to replace them.
<

> (5 min)

interesting, I don't work on such things but the few I have looked
at always had induction motors on them. I've never owned nor do I
even know any one that's ever had brushes replaced on their washing
machine..

Ours gets used almost every day and I replace them on the average
of every 5 years or so due to other problems, but never a motor..

In fact, I scabbed the motors from the last 2 I junked and both were
just AC induction. (squirrel cage types).

Jamie

 

[Andre Majorel]

To be very sure you disconect the motor and test it on the mains at a
reduced voltage.

The BTB15-600C is hard to find but RS carry the BTB16-600C.
Swapping in a new triac made no difference, though.

So I tried exactly what you're suggesting : motor on a big 24 V
transformer. If the rotor is a certain angle (or 180° from it),
the motor doesn't start when power is applied.

When you reverse the phase on the stator (for reverse), you
still have a pair of diametrically opposed "dead spots" but
they're at an angle from the original ones.

 

[Sylvia Else]

The BTB15-600C is hard to find but RS carry the BTB16-600C.
Swapping in a new triac made no difference, though.

So I tried exactly what you're suggesting : motor on a big 24 V
transformer. If the rotor is a certain angle (or 180° from it),
the motor doesn't start when power is applied.

When you reverse the phase on the stator (for reverse), you
still have a pair of diametrically opposed "dead spots" but
they're at an angle from the original ones.

That doesn't really sound right. Reversing the stator winding current
should reverse the force on the rotor, not change a zero force into a
non-zero force or vice versa.

I'd have to wonder whether one of the rotor windings has failed
open-cicuit. I think that could even account for the sparks. The
magnetic field for a winding that is becoming disconnected by the brush
action has to collapse because the broken winding that's being connected
cannot maintain the field.

Sylvia.

 

[Baron]

Sylvia Else Inscribed thus:

That doesn't really sound right. Reversing the stator winding current
should reverse the force on the rotor, not change a zero force into a
non-zero force or vice versa.

I'd have to wonder whether one of the rotor windings has failed
open-cicuit. I think that could even account for the sparks. The
magnetic field for a winding that is becoming disconnected by the
brush action has to collapse because the broken winding that's being
connected cannot maintain the field.

Sylvia.

Sounds like OC segments on the comm...

 

[Andre Majorel]

Sylvia Else Inscribed thus:


Sounds like OC segments on the comm...

The old man and I don't know enough about motors to be sure but
we did suspect something along the same lines.

We thought that even if we determined which winding is damaged,
attempting a fix would be risky and a lot of work. So we got a
used (but working) motor from electrodocas.fr. That fixed it.

Thanks folks.

 

[Baron]

Andre Majorel Inscribed thus:

The old man and I don't know enough about motors to be sure but
we did suspect something along the same lines.

Its easy enough to test. In the old days a buzz box was used, nowadays
no one bothers ! Its far cheaper just to throw it in the scrap box and
buy a new one.

I'll bet that if you look very carefully at the commutator segments, you
will find that one or more are loose and its likely that the loose
segment is OC.

We thought that even if we determined which winding is damaged,
attempting a fix would be risky and a lot of work.

Its very rare for the windings themselves to get damaged. Open or short
circuits at the commutator segments is very common.
I don't remember the last time I saw anybody repair a bad commutator !
Not on fractional motors/generators anyway.

So we got a used (but working) motor from electrodocas.fr. That fixed
it.

Thanks folks.

I reckon that you took the best course of action.

 

[Baron]

Michael A. Terrell Inscribed thus:

A 'Growler' was used to test the armature in a brush type motor.

Wow ! I haven't heard that term for a long time. Same kit or similar
though.

 

[PeterD]

Michael A. Terrell Inscribed thus:


Wow ! I haven't heard that term for a long time. Same kit or similar
though.

A growler is used to test for shorts, but won't test for opens. To test
for opens, one uses a simple ohm meter.