Heavy sparking fr brushes in a vac clnr.

A

Andy

Guest
I have a very rugged vacuum cleaner which started to behave strangely the
other day. When running, all of a sudden it just died. A gentle kick made it
run again! This went on for a while and then it started to run very badly,
like a 4 cyl engine running on 2 or 3. A smell of ozone was present as
well...
This convinced me to open it up and it didn't take long to find out that one
of the leads to the filter cap (x+2y) had broken. This was due to the cap
being a bit loose making it vibrate.
It was an easy task to find a new, similar, capacitor and assemble it all.
Then the test run made me disappointed. The motor ran, but badly as before
and the brushes was sparking *heavily*. What could it be?

Any tips or ideas are most welcome!
 
"Andy" <poyui@mmb.com> writes:

I have a very rugged vacuum cleaner which started to behave strangely the
other day. When running, all of a sudden it just died. A gentle kick made it
run again! This went on for a while and then it started to run very badly,
like a 4 cyl engine running on 2 or 3. A smell of ozone was present as
well...
This convinced me to open it up and it didn't take long to find out that one
of the leads to the filter cap (x+2y) had broken. This was due to the cap
being a bit loose making it vibrate.
It was an easy task to find a new, similar, capacitor and assemble it all.
Then the test run made me disappointed. The motor ran, but badly as before
and the brushes was sparking *heavily*. What could it be?

Any tips or ideas are most welcome!
Click to expand...
Are the brushes free to move and firmly against the commutator?

--- sam | Sci.Electronics.Repair FAQ Home Page: 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 Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
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"Sam Goldwasser" <sam@saul.cis.upenn.edu> skrev i meddelandet
news:6wzn8stl1z.fsf@saul.cis.upenn.edu...
"Andy" <poyui@mmb.com> writes:

I have a very rugged vacuum cleaner which started to behave strangely
the
other day. When running, all of a sudden it just died. A gentle kick
made it
run again! This went on for a while and then it started to run very
badly,
like a 4 cyl engine running on 2 or 3. A smell of ozone was present as
well...
This convinced me to open it up and it didn't take long to find out that
one
of the leads to the filter cap (x+2y) had broken. This was due to the
cap
being a bit loose making it vibrate.
It was an easy task to find a new, similar, capacitor and assemble it
all.
Then the test run made me disappointed. The motor ran, but badly as
before
and the brushes was sparking *heavily*. What could it be?

Any tips or ideas are most welcome!

Are the brushes free to move and firmly against the commutator?

--- sam | Sci.Electronics.Repair FAQ Home Page: 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 Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work.
To
contact me, please use the feedback form on the S.E.R FAQ Web sites.
Click to expand...
Yes, they are free to move and their surfaces look OK.
 
"Andy" <poyui@mmb.com> wrote in message
news:c6vuv3$vih$1@news.solace.mh.se...
I have a very rugged vacuum cleaner which started to behave strangely the
other day. When running, all of a sudden it just died. A gentle kick made
it
run again! This went on for a while and then it started to run very badly,
like a 4 cyl engine running on 2 or 3. A smell of ozone was present as
well...
This convinced me to open it up and it didn't take long to find out that
one
of the leads to the filter cap (x+2y) had broken. This was due to the cap
being a bit loose making it vibrate.
It was an easy task to find a new, similar, capacitor and assemble it all.
Then the test run made me disappointed. The motor ran, but badly as before
and the brushes was sparking *heavily*. What could it be?

Any tips or ideas are most welcome!
Click to expand...

The commutator segments on the armature of the motor may have been damaged
by the sparking. Disassemble the motor sufficiently so that you can get
access to the brushes and commutator. Get a small piece of emery paper or
emery cloth of about 400 grit and polish the commutator. Hold the emery
firmly against the commutator and rotate the armature so that the copper
segments are polished until they are smooth and shiny.

Make sure that the brushes are not pitted or grooved. If they are, replace
them. You should be able to get replacement brushes at an appliance parts
store.

--
Dave M

Good judgment comes from experience, and a lot of that comes from bad
judgement
 
Never use emery abrasives on non-ferrous metals. Clean up the commutator
with a file to smooth it; and, clean out the area between the segments
carefully with a small scraper. Replace the brushes with new ones. Flush out
any debris w/ electrical motor cleaner, but do not ruin the motor bearings
lubrication.
 
"Tweetldee" <masondg4499@comcast99.net> writes:

"Andy" <poyui@mmb.com> wrote in message
news:c6vuv3$vih$1@news.solace.mh.se...
I have a very rugged vacuum cleaner which started to behave strangely the
other day. When running, all of a sudden it just died. A gentle kick made
it
run again! This went on for a while and then it started to run very badly,
like a 4 cyl engine running on 2 or 3. A smell of ozone was present as
well...
This convinced me to open it up and it didn't take long to find out that
one
of the leads to the filter cap (x+2y) had broken. This was due to the cap
being a bit loose making it vibrate.
It was an easy task to find a new, similar, capacitor and assemble it all.
Then the test run made me disappointed. The motor ran, but badly as before
and the brushes was sparking *heavily*. What could it be?

Any tips or ideas are most welcome!


The commutator segments on the armature of the motor may have been damaged
by the sparking. Disassemble the motor sufficiently so that you can get
access to the brushes and commutator. Get a small piece of emery paper or
emery cloth of about 400 grit and polish the commutator. Hold the emery
firmly against the commutator and rotate the armature so that the copper
segments are polished until they are smooth and shiny.
Click to expand...
Probably better to use sandpaper - emery is conductive to some degree
and may leave all sorts of conductive stuff in the motor! Of course, so
is graphite so maybe it doesn't matter. You need to get as much of the
dust as possible out in any case.

Make sure that the brushes are not pitted or grooved. If they are, replace
them. You should be able to get replacement brushes at an appliance parts
store.
Click to expand...
Just wrap a piece of sandpaper around the commutation and rotate the
armature with some pressure on the brushes. That should form fit them
and remove the damage.

It's also possible that there are shorted turns in the coils which is
the real cause of the sparking.

If the sanding and polishing doesn't help and the brushes seat firmly
against the armature, then electrical problems are likely.

--- sam | Sci.Electronics.Repair FAQ Home Page: 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 Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the feedback form on the S.E.R FAQ Web sites.
 
Sam Goldwasser <sam@saul.cis.upenn.edu> wrote in message news:<6wzn8stl1z.fsf@saul.cis.upenn.edu>...
"Andy" <poyui@mmb.com> writes:

I have a very rugged vacuum cleaner which started to behave strangely the
other day. When running, all of a sudden it just died. A gentle kick made it
run again! This went on for a while and then it started to run very badly,
like a 4 cyl engine running on 2 or 3. A smell of ozone was present as
well...
This convinced me to open it up and it didn't take long to find out that one
of the leads to the filter cap (x+2y) had broken. This was due to the cap
being a bit loose making it vibrate.
It was an easy task to find a new, similar, capacitor and assemble it all.
Then the test run made me disappointed. The motor ran, but badly as before
and the brushes was sparking *heavily*. What could it be?

Any tips or ideas are most welcome!


Are the brushes free to move and firmly against the commutator?

--- sam | Sci.Electronics.Repair FAQ Home Page: 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 Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the feedback form on the S.E.R FAQ Web sites.

I face the same proplum. It was due the Armature short on one of the coil.
Click to expand...
 
OK, I will try that. One thing struck me, though. Is it possible that small
grains of copper could be between the segments, thus making a short?
Second: What is the expected resistance of the rotor. 1000 watts @ 230 volts
should yield 53 ohms, but I guess that AC makes things
complicated...XL=jwL...

"Sam Goldwasser" <sam@saul.cis.upenn.edu> skrev i meddelandet
news:6woep78x8d.fsf@saul.cis.upenn.edu...
"Tweetldee" <masondg4499@comcast99.net> writes:

"Andy" <poyui@mmb.com> wrote in message
news:c6vuv3$vih$1@news.solace.mh.se...
I have a very rugged vacuum cleaner which started to behave strangely
the
other day. When running, all of a sudden it just died. A gentle kick
made
it
run again! This went on for a while and then it started to run very
badly,
like a 4 cyl engine running on 2 or 3. A smell of ozone was present as
well...
This convinced me to open it up and it didn't take long to find out
that
one
of the leads to the filter cap (x+2y) had broken. This was due to the
cap
being a bit loose making it vibrate.
It was an easy task to find a new, similar, capacitor and assemble it
all.
Then the test run made me disappointed. The motor ran, but badly as
before
and the brushes was sparking *heavily*. What could it be?

Any tips or ideas are most welcome!


The commutator segments on the armature of the motor may have been
damaged
by the sparking. Disassemble the motor sufficiently so that you can get
access to the brushes and commutator. Get a small piece of emery paper
or
emery cloth of about 400 grit and polish the commutator. Hold the emery
firmly against the commutator and rotate the armature so that the copper
segments are polished until they are smooth and shiny.

Probably better to use sandpaper - emery is conductive to some degree
and may leave all sorts of conductive stuff in the motor! Of course, so
is graphite so maybe it doesn't matter. You need to get as much of the
dust as possible out in any case.

Make sure that the brushes are not pitted or grooved. If they are,
replace
them. You should be able to get replacement brushes at an appliance
parts
store.

Just wrap a piece of sandpaper around the commutation and rotate the
armature with some pressure on the brushes. That should form fit them
and remove the damage.

It's also possible that there are shorted turns in the coils which is
the real cause of the sparking.

If the sanding and polishing doesn't help and the brushes seat firmly
against the armature, then electrical problems are likely.

--- sam | Sci.Electronics.Repair FAQ Home Page: 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 Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work.
To
contact me, please use the feedback form on the S.E.R FAQ Web sites.
Click to expand...
 
"Andy" <poyui@mmb.com> writes:

OK, I will try that. One thing struck me, though. Is it possible that small
grains of copper could be between the segments, thus making a short?
Second: What is the expected resistance of the rotor. 1000 watts @ 230 volts
should yield 53 ohms, but I guess that AC makes things
complicated...XL=jwL...
Click to expand...
Yes indeed. As someone else suggested, clean the communatator including
between segments.

And yes indeed, AC does change things. What you can check is that the
resistance between segments on opposite sides of the commutator should
be about the same for all (well, 1/2) the segments.

--- sam | Sci.Electronics.Repair FAQ Home Page: 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 Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the feedback form on the S.E.R FAQ Web sites.
 
Damn, this thing makes me crazy! I have measured all the windings. 0.2 ohms
between to neighboring segments yielding a total of ca 2 ohms between
opposite segments. Everything seems to be in order, and still, the brushes
spark more than the sky on New Years Eve...

"Sam Goldwasser" <sam@saul.cis.upenn.edu> skrev i meddelandet
news:6whduzxckm.fsf@saul.cis.upenn.edu...
"Andy" <poyui@mmb.com> writes:

OK, I will try that. One thing struck me, though. Is it possible that
small
grains of copper could be between the segments, thus making a short?
Second: What is the expected resistance of the rotor. 1000 watts @ 230
volts
should yield 53 ohms, but I guess that AC makes things
complicated...XL=jwL...

Yes indeed. As someone else suggested, clean the communatator including
between segments.

And yes indeed, AC does change things. What you can check is that the
resistance between segments on opposite sides of the commutator should
be about the same for all (well, 1/2) the segments.

--- sam | Sci.Electronics.Repair FAQ Home Page: 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 Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work.
To
contact me, please use the feedback form on the S.E.R FAQ Web sites.
Click to expand...
 
"Andy" <poyui@mmb.com> wrote in message
news:c7gq2b$kqj$1@news.solace.mh.se...
Damn, this thing makes me crazy! I have measured all the windings. 0.2
ohms
between to neighboring segments yielding a total of ca 2 ohms between
opposite segments. Everything seems to be in order, and still, the brushes
spark more than the sky on New Years Eve...

"Sam Goldwasser" <sam@saul.cis.upenn.edu> skrev i meddelandet
news:6whduzxckm.fsf@saul.cis.upenn.edu...
"Andy" <poyui@mmb.com> writes:

OK, I will try that. One thing struck me, though. Is it possible that
small
grains of copper could be between the segments, thus making a short?
Second: What is the expected resistance of the rotor. 1000 watts @ 230
volts
should yield 53 ohms, but I guess that AC makes things
complicated...XL=jwL...

Yes indeed. As someone else suggested, clean the communatator including
between segments.

And yes indeed, AC does change things. What you can check is that the
resistance between segments on opposite sides of the commutator should
be about the same for all (well, 1/2) the segments.

--- sam | Sci.Electronics.Repair FAQ Home Page:
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 Site Info:
http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work.
To
contact me, please use the feedback form on the S.E.R FAQ Web sites.




The conventional test is to put the armature on a 'growler' and test for
Click to expand...
shorts and opens, however if the sparkes are 'heavy' and strong there would
be shorts in it, open circuit windings give long trailing sparkes around the
commy and also the edges of the open circuit comm bars will be burnt. Since
you have tested for continuity I would guess there are shorts, they are hard
to find with a VOM.

--
Regards ........... Rheilly Phoull
 
On Fri, 7 May 2004 22:03:00 +0200 "Andy" <poyui@mmb.com> wrote:

Damn, this thing makes me crazy! I have measured all the windings. 0.2 ohms
between to neighboring segments yielding a total of ca 2 ohms between
opposite segments. Everything seems to be in order, and still, the brushes
spark more than the sky on New Years Eve...
Click to expand...
A commutator that is rough, or out of round, will also cause sparking.

I don't know, but if it is a series wound motor with shorts in the
field winding, then it would draw excessive current thru the brushes
which could also cause sparking even if there was nothing wrong with
the commutator or the brushes.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------
 
"Andy" <poyui@mmb.com> wrote in message news:<c7gq2b$kqj$1@news.solace.mh.se>...
Damn, this thing makes me crazy! I have measured all the windings. 0.2 ohms
between to neighboring segments yielding a total of ca 2 ohms between
opposite segments. Everything seems to be in order, and still, the brushes
spark more than the sky on New Years Eve...
Click to expand...
What everybody has overlooked is that a single shorted turn on any one
of the commutator coils is not going to lower the apparent resistance
of that coil enough to be detectable, but it will kill the inductance
of that coil and cause fireworks as described by the poster. If
anyone has an extra motor, just try it and see. :)

H. R. (Bob) Hofmann
 
I noticed that the new x-y filter is configured as 2 x 4700pF + 0.10uF
whereas the old was 2 x 4700pF + 0.15uF. I assume that this gizmo is only
there to reduce RFI but could the lower capacitance cause the sparking as
well?

Thanks for all your contributions on this neverending story! :)

"Rheilly Phoull" <Rheilly@bigpong.com> skrev i meddelandet
news:2g3bbfF3tt83U1@uni-berlin.de...
"Andy" <poyui@mmb.com> wrote in message
news:c7gq2b$kqj$1@news.solace.mh.se...
Damn, this thing makes me crazy! I have measured all the windings. 0.2
ohms
between to neighboring segments yielding a total of ca 2 ohms between
opposite segments. Everything seems to be in order, and still, the
brushes
spark more than the sky on New Years Eve...

"Sam Goldwasser" <sam@saul.cis.upenn.edu> skrev i meddelandet
news:6whduzxckm.fsf@saul.cis.upenn.edu...
"Andy" <poyui@mmb.com> writes:

OK, I will try that. One thing struck me, though. Is it possible
that
small
grains of copper could be between the segments, thus making a short?
Second: What is the expected resistance of the rotor. 1000 watts @
230
volts
should yield 53 ohms, but I guess that AC makes things
complicated...XL=jwL...

Yes indeed. As someone else suggested, clean the communatator
including
between segments.

And yes indeed, AC does change things. What you can check is that the
resistance between segments on opposite sides of the commutator should
be about the same for all (well, 1/2) the segments.

--- sam | Sci.Electronics.Repair FAQ Home Page:
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 Site Info:
http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer
work.
To
contact me, please use the feedback form on the S.E.R FAQ Web sites.




The conventional test is to put the armature on a 'growler' and test for
shorts and opens, however if the sparkes are 'heavy' and strong there
would
be shorts in it, open circuit windings give long trailing sparkes around
the
commy and also the edges of the open circuit comm bars will be burnt.
Since
you have tested for continuity I would guess there are shorts, they are
hard
to find with a VOM.

--
Regards ........... Rheilly Phoull
Click to expand...
 
"H. R. Bob Hofmann" <hrhofmann@att.net> wrote in message
news:deadaa59.0405080552.475f7335@posting.google.com...
"Andy" <poyui@mmb.com> wrote in message
news:<c7gq2b$kqj$1@news.solace.mh.se>...
Damn, this thing makes me crazy! I have measured all the windings. 0.2
ohms
between to neighboring segments yielding a total of ca 2 ohms between
opposite segments. Everything seems to be in order, and still, the
brushes
spark more than the sky on New Years Eve...

What everybody has overlooked is that a single shorted turn on any one
of the commutator coils is not going to lower the apparent resistance
of that coil enough to be detectable, but it will kill the inductance
of that coil and cause fireworks as described by the poster. If
anyone has an extra motor, just try it and see. :)

H. R. (Bob) Hofmann
Click to expand...
An ESR meter or flyback transformer tester should work to test for shorted
turns.
 
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