M
Mike
Hi All,
Our 2-year old vacuum cleaner (Kenmore Whispertone model - cannister type),
seized up recently with a burner odor coming from the cannister compartment.
I pulled the unit apart and measured the voltage at the input terminals to
this integrated motor fan unit and it was in fact 120V as it should be.
The on/off switch is on the handle of the vacuum cleaner and with the switch
open, the motor armature still makes an intermittment revolutions while
connected to grid power. But then eventually stops. Looking at the carbon
brushes, they seem fine. There is a little bit of a build up around the
brushes at the brush/slip ring interface. I ran it down to a local Vacuum
repair shop and the fellow looked at it ever so briefly and said its a throw
away and tried to sell me another vacuum. He indicated that the "field
unit" was dead. Now from my understanding of electric motors (which is
limited I admit), is that terminals connect to a series of field coil pairs
with lots of copper windings which ultimately creates magnetic flux between
these corresponding pole pairs causing the armature to rotate in the
presence of the flux lines, so the principle concept here is
electromagnetism as I understand it. Hence, I believe the primary
components are magnetic pole pairs affixed to the stator, lots of copper
windings, an armature connected to the fan, carbon brushes and slip rings.
Now, I am assuming that this motor is constructed in a similar fashion.
Can anyone suggest some of the potential failure points in this motors? Are
they typically field serviceable? How does a "field unit" (not really
knowing what he meant and I asked for clarification but didn't get any from
the fellow) die? Is it possibly a case where the windings from a given
field coil are shorting to another set of windings? Can you rebuild these
units easily? The replacement unit from Sears is $115 which accounts for
33% of the vacuum brand new. I have an electronics engineering background
buts its been a while. I do have a fully equipped bench at home if
necessary but I think this probably requires me to physically rewind the
field coils more than anything else ... ? Am I on the right track? Or
have i missed something?
Do these types of units typically have any capacitors in them which would
potentially introduce a safety concern when opening it up while unplugged
.... would need to discharge them accordingly? I wouldn't think so but not
sure. Any / all info would be great. I would much rather fix it myself if
possible.
What would account for the burning odor? copper melting? Are the windings
typically enamaled or insulated? From what I could see, peering inside, it
didn't look like it. It almost smelt like rubber???
Thanks in advance!
--Mike
Our 2-year old vacuum cleaner (Kenmore Whispertone model - cannister type),
seized up recently with a burner odor coming from the cannister compartment.
I pulled the unit apart and measured the voltage at the input terminals to
this integrated motor fan unit and it was in fact 120V as it should be.
The on/off switch is on the handle of the vacuum cleaner and with the switch
open, the motor armature still makes an intermittment revolutions while
connected to grid power. But then eventually stops. Looking at the carbon
brushes, they seem fine. There is a little bit of a build up around the
brushes at the brush/slip ring interface. I ran it down to a local Vacuum
repair shop and the fellow looked at it ever so briefly and said its a throw
away and tried to sell me another vacuum. He indicated that the "field
unit" was dead. Now from my understanding of electric motors (which is
limited I admit), is that terminals connect to a series of field coil pairs
with lots of copper windings which ultimately creates magnetic flux between
these corresponding pole pairs causing the armature to rotate in the
presence of the flux lines, so the principle concept here is
electromagnetism as I understand it. Hence, I believe the primary
components are magnetic pole pairs affixed to the stator, lots of copper
windings, an armature connected to the fan, carbon brushes and slip rings.
Now, I am assuming that this motor is constructed in a similar fashion.
Can anyone suggest some of the potential failure points in this motors? Are
they typically field serviceable? How does a "field unit" (not really
knowing what he meant and I asked for clarification but didn't get any from
the fellow) die? Is it possibly a case where the windings from a given
field coil are shorting to another set of windings? Can you rebuild these
units easily? The replacement unit from Sears is $115 which accounts for
33% of the vacuum brand new. I have an electronics engineering background
buts its been a while. I do have a fully equipped bench at home if
necessary but I think this probably requires me to physically rewind the
field coils more than anything else ... ? Am I on the right track? Or
have i missed something?
Do these types of units typically have any capacitors in them which would
potentially introduce a safety concern when opening it up while unplugged
.... would need to discharge them accordingly? I wouldn't think so but not
sure. Any / all info would be great. I would much rather fix it myself if
possible.
What would account for the burning odor? copper melting? Are the windings
typically enamaled or insulated? From what I could see, peering inside, it
didn't look like it. It almost smelt like rubber???
Thanks in advance!
--Mike