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Mk5 motor troubleshooting/Viejo
Posted: Sun Jun 10, 2018 10:52 pm
by Viejo
JPG- you're right, the motor did not jerk but simply stopped after a very brief attempt at rotation and then continued to hum until I opened the switch (~1.5 seconds).
Cheers,
Dave
Re: Mk5 motor troubleshooting/Viejo
Posted: Sun Jun 10, 2018 11:25 pm
by JPG
1.5 seconds is good news! Not long enough to cause damage.
The motor 'start' circuit consists of three things.
1) the start windings.
2) the start capacitor
3) the start switch.
Those three things are connected in series(daisy chained)
The motor 'run' windings are directly connected to the external wires.
It is the 'run' windings that create the hum.
When power is applied to the external wires, both the run windings and the series start circuit are energized.
The most likely culprit to fail in the start circuit is the start switch.
At rest the switch contacts are closed and complete the series circuit so current flows to the start windings through the capacitor. This causes the armature to start to rotate(ain't really all that simple, but for current purposes it will suffice).
As the armature increases rpms a centrifugal mechanism opens the start switch contacts and the start circuit becomes non energized.
When it is turned off, the centrifugal mechanism closes the start switch and the cycle is set to repeat.
So we need to take a close look at the start switch. It is inside the motor(unless it is a GE motor with an external start relay).
Nuf fer now!
Re: Mk5 motor troubleshooting/Viejo
Posted: Mon Jun 11, 2018 10:28 am
by Viejo
JPG wrote:1.5 seconds is good news! Not long enough to cause damage.
The motor 'start' circuit consists of three things.
1) the start windings.
2) the start capacitor
3) the start switch.
Those three things are connected in series(daisy chained)
The motor 'run' windings are directly connected to the external wires.
It is the 'run' windings that create the hum.
When power is applied to the external wires, both the run windings and the series start circuit are energized.
The most likely culprit to fail in the start circuit is the start switch.
At rest the switch contacts are closed and complete the series circuit so current flows to the start windings through the capacitor. This causes the armature to start to rotate(ain't really all that simple, but for current purposes it will suffice).
As the armature increases rpms a centrifugal mechanism opens the start switch contacts and the start circuit becomes non energized.
When it is turned off, the centrifugal mechanism closes the start switch and the cycle is set to repeat.
So we need to take a close look at the start switch. It is inside the motor(unless it is a GE motor with an external start relay).
Nuf fer now!
JPG- got it, thanks!... will update when the dust settles.