The Gorton 2-28 milling machine that I put in my shop recently, works
great, with one exception: its power feed for the X axis is not
working.

The way it is supposed to work is via a DC motor, controlled by a
simple DC drive. The DC motor has a field winding.

The problem is that the motor does not run.

The DC drive does supply voltage to both F1-F2 and A1-A2. I interpret
those as field and motor windings. F2 and A2 are connected together
and voltage between that point and F1 or A1 is 50 volts.

I opened the motor up. When opened, I tested voltage between brushes
and found out that there is 0 volts between brushes, or brushes and
armature.

How can I interpret this finding and what is the usual cause of such
behaviour.

The motor was really dirty inside, I washed it in a parts washer, but
have not yet reassembled, since I could not find the problem.

Thanks

"Ignoramus9202" wrote in message
...
The Gorton 2-28 milling machine that I put in my shop recently, works
great, with one exception: its power feed for the X axis is not
working.

The way it is supposed to work is via a DC motor, controlled by a
simple DC drive. The DC motor has a field winding.

The problem is that the motor does not run.

The DC drive does supply voltage to both F1-F2 and A1-A2. I interpret
those as field and motor windings. F2 and A2 are connected together
and voltage between that point and F1 or A1 is 50 volts.

I opened the motor up. When opened, I tested voltage between brushes
and found out that there is 0 volts between brushes, or brushes and
armature.

How can I interpret this finding and what is the usual cause of such
behaviour.

The motor was really dirty inside, I washed it in a parts washer, but
have not yet reassembled, since I could not find the problem.

Thanks

Sounds like one of the flex wires connecting the carbon part of the brush
to the brush holder is open. Or the connection between A1 or A2 and the
brush holder is open.
Art

"Artemus" fired this volley in news:kmmj0j$8a5$1
@dont-email.me:

Sounds like one of the flex wires connecting the carbon part of the
brush
to the brush holder is open. Or the connection between A1 or A2 and
the
brush holder is open.
Art

Yup.

There's not much can go wrong there, Ig. Check the voltage between the
inlet terminal for A1 or A2 and its corresponding brush holder.

If there's anything more than a nuisance couple of volts, you've got a
break between the A1 or A2 terminal and its corresponding brush.


LLoyd

On May 11, 6:50*pm, Ignoramus9202
wrote:

The problem is that the motor does not run.

e.

How can I interpret this finding and what is the usual cause of such
behaviour.


Thanks

You might check to see if the brushes are worn so much that they do
not quite contact the armature.


Dan

" fired this volley in news:4ed26075-
:

You might check to see if the brushes are worn so much that they do
not quite contact the armature.

How would that result in zero voltage between the brushes themselves or
between their guides/housings?

Yes, worn brushes would cause the symptom. But he's already reported a
troubleshooting symptom that indicates that would not be the problem.

LLoyd

On Sat, 11 May 2013 17:50:58 -0500, Ignoramus9202
wrote:

The Gorton 2-28 milling machine that I put in my shop recently, works
great, with one exception: its power feed for the X axis is not
working.

The way it is supposed to work is via a DC motor, controlled by a
simple DC drive. The DC motor has a field winding.

The problem is that the motor does not run.

The DC drive does supply voltage to both F1-F2 and A1-A2. I interpret
those as field and motor windings. F2 and A2 are connected together
and voltage between that point and F1 or A1 is 50 volts.

I opened the motor up. When opened, I tested voltage between brushes
and found out that there is 0 volts between brushes, or brushes and
armature.

How can I interpret this finding and what is the usual cause of such
behaviour.

The motor was really dirty inside, I washed it in a parts washer, but
have not yet reassembled, since I could not find the problem.

Thanks

Sounds like your armature is burned out.


--
"You guess the truth hurts?

Really?

"Hurt" aint the word.

For Liberals, the truth is like salt to a slug.
Sunlight to a vampire.
Raid® to a cockroach.
Sheriff Brody to a shark
Bush to a Liberal

The truth doesn't just hurt. It's painful, like a red hot poker shoved
up their ass. Like sliding down a hundred foot razor blade using their
dick as a brake.

They HATE the truth."

On 2013-05-11, Artemus wrote:

"Ignoramus9202" wrote in message
...
The Gorton 2-28 milling machine that I put in my shop recently, works
great, with one exception: its power feed for the X axis is not
working.

The way it is supposed to work is via a DC motor, controlled by a
simple DC drive. The DC motor has a field winding.

The problem is that the motor does not run.

The DC drive does supply voltage to both F1-F2 and A1-A2. I interpret
those as field and motor windings. F2 and A2 are connected together
and voltage between that point and F1 or A1 is 50 volts.

I opened the motor up. When opened, I tested voltage between brushes
and found out that there is 0 volts between brushes, or brushes and
armature.

How can I interpret this finding and what is the usual cause of such
behaviour.

The motor was really dirty inside, I washed it in a parts washer, but
have not yet reassembled, since I could not find the problem.

Thanks

Sounds like one of the flex wires connecting the carbon part of the brush
to the brush holder is open. Or the connection between A1 or A2 and the
brush holder is open.
Art



Makes sense, great idea

On 2013-05-12, Lloyd E. Sponenburgh lloydspinsidemindspring.com wrote:
" fired this volley in news:4ed26075-
:

You might check to see if the brushes are worn so much that they do
not quite contact the armature.

How would that result in zero voltage between the brushes themselves or
between their guides/housings?

Yes, worn brushes would cause the symptom. But he's already reported a
troubleshooting symptom that indicates that would not be the problem.

Right. No voltage between brushes.

Additionally, the armature is worn quite a bit. This mill, it seems,
has this design that the power feed motor runs all the time, and is
engaged and disengaged with a mechanical gear, it does not really turn
off.

i

On Sat, 11 May 2013 17:50:58 -0500, Ignoramus9202
wrote:

The Gorton 2-28 milling machine that I put in my shop recently, works
great, with one exception: its power feed for the X axis is not
working.

The way it is supposed to work is via a DC motor, controlled by a
simple DC drive. The DC motor has a field winding.

The problem is that the motor does not run.

The DC drive does supply voltage to both F1-F2 and A1-A2. I interpret
those as field and motor windings. F2 and A2 are connected together
and voltage between that point and F1 or A1 is 50 volts.

I opened the motor up. When opened, I tested voltage between brushes
and found out that there is 0 volts between brushes, or brushes and
armature.

Check the armature. (My VOM has a beeper mode which speeds things up
in cases like this.) Opposite commutators usually connected by a
winding (180 degrees apart when the brushes are set in that position.)
Also verify that none of the commutators are shorted to the shaft,
then verify that the commutator is connected to the wire it's
supposedly soldered to. Sometimes the brush can wear off the solder
and lose a connection, but that just ends in a motor which won't start
in certain positions. Verify that each brush and its connector are
actually intact. Some had carbon rather than wire inside and it can
degrade.


How can I interpret this finding and what is the usual cause of such
behaviour.

Logically, as you usually do.


The motor was really dirty inside, I washed it in a parts washer, but
have not yet reassembled, since I could not find the problem.

Sometimes it's just dirty and cleaning/reassembly fixes it. Do the
individual tests. If you find nothing, assemble and try again. I've
brought home dozens of "broken" or "burned out" electrical products
which had a grain of sand between working and not working. I've made
hundreds (if not thousands) of dollars reselling the working product.

--
Cogito, ergo armatum sum.

(I think, therefore I am armed.)

Ignoramus9202 fired this volley in
:

Additionally, the armature is worn quite a bit. This mill, it seems,
has this design that the power feed motor runs all the time, and is
engaged and disengaged with a mechanical gear, it does not really turn
off.

Armatures don't wear, Ig, unless the bearings are so bad that it's been
rubbing on the field steel.

COMMUTATORS wear. If they're made of thick enough copper, they can be
trued up and undercut like new. If not, you toss it.

Lloyd

On 2013-05-12, Larry Jaques wrote:
On Sat, 11 May 2013 17:50:58 -0500, Ignoramus9202
wrote:

The Gorton 2-28 milling machine that I put in my shop recently, works
great, with one exception: its power feed for the X axis is not
working.

The way it is supposed to work is via a DC motor, controlled by a
simple DC drive. The DC motor has a field winding.

The problem is that the motor does not run.

The DC drive does supply voltage to both F1-F2 and A1-A2. I interpret
those as field and motor windings. F2 and A2 are connected together
and voltage between that point and F1 or A1 is 50 volts.

I opened the motor up. When opened, I tested voltage between brushes
and found out that there is 0 volts between brushes, or brushes and
armature.

Check the armature. (My VOM has a beeper mode which speeds things up
in cases like this.) Opposite commutators usually connected by a
winding (180 degrees apart when the brushes are set in that position.)
Also verify that none of the commutators are shorted to the shaft,
then verify that the commutator is connected to the wire it's
supposedly soldered to. Sometimes the brush can wear off the solder
and lose a connection, but that just ends in a motor which won't start
in certain positions. Verify that each brush and its connector are
actually intact. Some had carbon rather than wire inside and it can
degrade.


How can I interpret this finding and what is the usual cause of such
behaviour.

Logically, as you usually do.


The motor was really dirty inside, I washed it in a parts washer, but
have not yet reassembled, since I could not find the problem.

Sometimes it's just dirty and cleaning/reassembly fixes it. Do the
individual tests. If you find nothing, assemble and try again. I've
brought home dozens of "broken" or "burned out" electrical products
which had a grain of sand between working and not working. I've made
hundreds (if not thousands) of dollars reselling the working product.


(I think, therefore I am armed.)

Yep. I will post updates when I am done figuring it out. Thanks

i

It would be worthwhile to include more details in your posts, as you've been
criticised for previously.. so days later someone may realize what it is
your talking about.

This drive got a name, p/n, or voltage marked on it? Someone may have a
schematic/wiring diagram or other useful info for a similar drive if you
would give details.

It appears that a voltage is present for the field (but it may not be the
correct voltage).
The motor also needs an armature voltage A1-A2.

The armature voltage isn't getting to the armature.
Failed drive circuitry.
Switch device open.
Half-assed previous repair/anything.
The armature voltage is the one that's controlled by the circuit.. any of
the components associated with the motor speed could have failed.
I've read more than a couple of times that speed pots had failed in a
certain table drive.. Enco maybe. There may be some info and/or a schematic
in the dropbox archives.

It may be that the drive motor runs all the time because it failed before
and some motor monkey found a way to make it run.

You've seen considerable wear present, but you'll likely spend hours trying
to make the old drive work, possibly poorly or only briefly, then hold out
for another used drive for cheap.
Possibly you were thinking you'd get an old machine that you'd be able to
use for years without ever spending a dime on it.

The machine probably didn't cost much but if you aren't willing to spend
some money on it, you probably just dragged it back to scrap it.

Plan B.. put a handwheel on the feedscrew.. which is a good plan, that may
even dissuade the operator from walking away from an operating machine.

--
WB
..........


"Ignoramus9202" wrote in message
...
The Gorton 2-28 milling machine that I put in my shop recently, works
great, with one exception: its power feed for the X axis is not
working.

The way it is supposed to work is via a DC motor, controlled by a
simple DC drive. The DC motor has a field winding.

The problem is that the motor does not run.

The DC drive does supply voltage to both F1-F2 and A1-A2. I interpret
those as field and motor windings. F2 and A2 are connected together
and voltage between that point and F1 or A1 is 50 volts.

I opened the motor up. When opened, I tested voltage between brushes
and found out that there is 0 volts between brushes, or brushes and
armature.

How can I interpret this finding and what is the usual cause of such
behaviour.

The motor was really dirty inside, I washed it in a parts washer, but
have not yet reassembled, since I could not find the problem.

Thanks

On May 11, 9:31*pm, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:
" fired this volley in news:4ed26075-
:

You *might check to see if the brushes are worn so much that they do
not quite contact the armature.

How would that result in zero voltage between the brushes themselves or
between their guides/housings?

Yes, worn brushes would cause the symptom. *But he's already reported a
troubleshooting symptom that indicates that would not be the problem.

LLoyd


I kind of assumed that Iggy would have also checked the voltage
between A1 and both of the brushes and between A2 and both of the
brushes while he had the meter in his hands. If he did and did not
find the problem, then his readings do not make sense and something
was mismeasured. So time to recheck what he thinks he knows. There is
always the possibility that there are two problems , which makes it a
bit harder to figure out what is happening.

Besides he needs to check the brushes for excessive wear while he has
it apart.


Dan

Ignoramus9202 fired this volley in
:

Yep. I will post updates when I am done figuring it out. Thanks

Ig,
It's somewhere near worthless and a waste of time to post any details
until you get it solved.

Ig, it's apparent that some folks refuse to read your first post, wanting
instead to make the problem fit their solution. However, three people
all suggested the same, useful thing.

Ig... those who suggested checking continuity between the "A", leads and
the brush holders shouldn't have had to make that suggestion. That check
should have been a natural part of your protocol to begin with, as soon
as you saw power to the A leads, but none on the brushes themselves.
(just a small finger-wagging G)

LLoyd

On 2013-05-12, jeff wrote:
On Sat, 11 May 2013 22:01:48 -0400, jeff wrote:

On Sat, 11 May 2013 17:50:58 -0500, Ignoramus9202
wrote:

The Gorton 2-28 milling machine that I put in my shop recently, works
great, with one exception: its power feed for the X axis is not
working.

The way it is supposed to work is via a DC motor, controlled by a
simple DC drive. The DC motor has a field winding.

The problem is that the motor does not run.

The DC drive does supply voltage to both F1-F2 and A1-A2. I interpret
those as field and motor windings. F2 and A2 are connected together
and voltage between that point and F1 or A1 is 50 volts.

I opened the motor up. When opened, I tested voltage between brushes
and found out that there is 0 volts between brushes, or brushes and
armature.

How can I interpret this finding and what is the usual cause of such
behaviour.

The motor was really dirty inside, I washed it in a parts washer, but
have not yet reassembled, since I could not find the problem.

Thanks
F1and F2 Field A1 and A2 armature. Unhook all wires and check
continuity across f1 and f2 a1 and a2. Both should have very low
resistance. If your getting 50 volts in and out then sounds like
your missing the negative from the drive.
Is the motor fed voltage from the drive with two or four wires?

Three wires from the drive, connecting to four wires to the motor.

i

On 2013-05-12, Lloyd E. Sponenburgh lloydspinsidemindspring.com wrote:
Ignoramus9202 fired this volley in
:

Yep. I will post updates when I am done figuring it out. Thanks

Ig,
It's somewhere near worthless and a waste of time to post any details
until you get it solved.

Ig, it's apparent that some folks refuse to read your first post, wanting
instead to make the problem fit their solution. However, three people
all suggested the same, useful thing.

Ig... those who suggested checking continuity between the "A", leads and
the brush holders shouldn't have had to make that suggestion. That check
should have been a natural part of your protocol to begin with, as soon
as you saw power to the A leads, but none on the brushes themselves.
(just a small finger-wagging G)

LLoyd

You are right. I decided to take the stator off and wash it before
proceeding, due to it being extremely dirty.

i

jeff fired this volley in
:

Guess I can't help you then. Most dc motors I work on require
either two or four power leads. Waiting to see what you find.


Didn't read the post? It HAS two windings, and four leads. Two to
field, two to armature.

It just _happens_ that the field and armature power supplies share a
common. That does just occasionally happen in electrical stuff -- that
two supplies might share a common ground... even bipolar supplies are
usually ground-referenced.

Lloyd

On Sun, 12 May 2013 20:37:08 -0400, jeff wrote:

On Sun, 12 May 2013 08:22:58 -0500, Ignoramus5857
wrote:

On 2013-05-12, jeff wrote:
On Sat, 11 May 2013 22:01:48 -0400, jeff wrote:

On Sat, 11 May 2013 17:50:58 -0500, Ignoramus9202
wrote:

The Gorton 2-28 milling machine that I put in my shop recently, works
great, with one exception: its power feed for the X axis is not
working.

The way it is supposed to work is via a DC motor, controlled by a
simple DC drive. The DC motor has a field winding.

The problem is that the motor does not run.

The DC drive does supply voltage to both F1-F2 and A1-A2. I interpret
those as field and motor windings. F2 and A2 are connected together
and voltage between that point and F1 or A1 is 50 volts.

I opened the motor up. When opened, I tested voltage between brushes
and found out that there is 0 volts between brushes, or brushes and
armature.

How can I interpret this finding and what is the usual cause of such
behaviour.

The motor was really dirty inside, I washed it in a parts washer, but
have not yet reassembled, since I could not find the problem.

Thanks
F1and F2 Field A1 and A2 armature. Unhook all wires and check
continuity across f1 and f2 a1 and a2. Both should have very low
resistance. If your getting 50 volts in and out then sounds like
your missing the negative from the drive.
Is the motor fed voltage from the drive with two or four wires?

Three wires from the drive, connecting to four wires to the motor.

i
???? Guess I can't help you then. Most dc motors I work on require
either two or four power leads. Waiting to see what you find.
Common ground externally excited field shunt motor.. Speed changes
as the ballance between the feild and armature changes - the stronger
the field, the slower the engine.

To test the motor check continuity between f1 and f2, and between a1
and a2 with the motor assembled. If you have armature continuity and
not field continuity, you are likely to burn out the armature quite
quickly as the armature will be pretty close to a short. An open
field is pretty well indicative of a burned out field.

If the armature is open, turn the motor and see if it is intermittent.
If so, the armature is burned out. If not, there is a bad connection
from either A1 or A2 and the brush assigned to it.

Really a pretty simple thing to test - not necessarilly easy to fix..

If you have continuity on both, connect a1 to f1 and a2 to f2, and
connect jumper cables from 12 volt battery to the a1f1 and a2f2
connections and the motor should run.. Connect a1f2 and a2f1 and the
motor should reverse.

If that works, your "drive" or controller is damaged.

On 2013-05-13, wrote:
On Sun, 12 May 2013 20:37:08 -0400, jeff wrote:

On Sun, 12 May 2013 08:22:58 -0500, Ignoramus5857
wrote:

On 2013-05-12, jeff wrote:
On Sat, 11 May 2013 22:01:48 -0400, jeff wrote:

On Sat, 11 May 2013 17:50:58 -0500, Ignoramus9202
wrote:

The Gorton 2-28 milling machine that I put in my shop recently, works
great, with one exception: its power feed for the X axis is not
working.

The way it is supposed to work is via a DC motor, controlled by a
simple DC drive. The DC motor has a field winding.

The problem is that the motor does not run.

The DC drive does supply voltage to both F1-F2 and A1-A2. I interpret
those as field and motor windings. F2 and A2 are connected together
and voltage between that point and F1 or A1 is 50 volts.

I opened the motor up. When opened, I tested voltage between brushes
and found out that there is 0 volts between brushes, or brushes and
armature.

How can I interpret this finding and what is the usual cause of such
behaviour.

The motor was really dirty inside, I washed it in a parts washer, but
have not yet reassembled, since I could not find the problem.

Thanks
F1and F2 Field A1 and A2 armature. Unhook all wires and check
continuity across f1 and f2 a1 and a2. Both should have very low
resistance. If your getting 50 volts in and out then sounds like
your missing the negative from the drive.
Is the motor fed voltage from the drive with two or four wires?

Three wires from the drive, connecting to four wires to the motor.

i
???? Guess I can't help you then. Most dc motors I work on require
either two or four power leads. Waiting to see what you find.
Common ground externally excited field shunt motor.. Speed changes
as the ballance between the feild and armature changes - the stronger
the field, the slower the engine.

To test the motor check continuity between f1 and f2, and between a1
and a2 with the motor assembled. If you have armature continuity and
not field continuity, you are likely to burn out the armature quite
quickly as the armature will be pretty close to a short. An open
field is pretty well indicative of a burned out field.

If the armature is open, turn the motor and see if it is intermittent.
If so, the armature is burned out. If not, there is a bad connection
from either A1 or A2 and the brush assigned to it.

Really a pretty simple thing to test - not necessarilly easy to fix..

If you have continuity on both, connect a1 to f1 and a2 to f2, and
connect jumper cables from 12 volt battery to the a1f1 and a2f2
connections and the motor should run.. Connect a1f2 and a2f1 and the
motor should reverse.

If that works, your "drive" or controller is damaged.

Yep. I will check all that tomorrow.

On Mon, 13 May 2013 20:36:58 -0400, jeff wrote:

On Sun, 12 May 2013 19:47:19 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

jeff fired this volley in
m:

Guess I can't help you then. Most dc motors I work on require
either two or four power leads. Waiting to see what you find.


Didn't read the post? It HAS two windings, and four leads. Two to
field, two to armature.

It just _happens_ that the field and armature power supplies share a
common. That does just occasionally happen in electrical stuff -- that
two supplies might share a common ground... even bipolar supplies are
usually ground-referenced.

Lloyd
Lloyd, I did read his post, several times in fact. I did not fire a
volley, one shot only, trying to hit the target.....

I am not trying to cause problems here, just trying to help where I
think I can as I do have experience in things DC albeit in the
forklift trade.

If I'm reading it correctly his motor sounds like any other dc motor
that is not a permanent magnet motor. It has a field winding F1 F2
and an armature with a commutator that brushs ride on A1 A2.

The fact that it only has three leads is what confuses me.

Either way supply voltage out the controller + or - will enter the
armature go through the fields and then back to the controller causing
the armature to rotate. Pulse Width Modulation will control the speed
and torque of said motor.

You are assuming it is a series traction motor - which would be
useless on a feed screw because it has no speed regulation. This is
almost CERTAINLY a shunt motor - with variable field current to
control the speed - quite accurately in fact - independent of load.
Your fork lift experience is helpfull as far as it goes, but it
doesn't go far enough.

If by any chance this is a separately excited motor, the field cables
are normally smaller then the armature cables. The fields and armature
would each be supplied voltage via the controller which would to my
knowledge take four motor leads. Seeing as this has
( THREE ) motor leads with one connected to both A2 and F2 the other
two must go to A1 and F1. The single wire to A2 F2 would be the
positive in, according to Iggy 50 volts and the other two would be
would be pulsed negatve from the controller but since Iggy said it was
a SIMPLE DC DRIVE I didn't think it was that kind of motor.

The fact that he has fifty volts at A2 F2 out to A1 and also F1 would
suggest that the motor is ok.

My thoughts are that the drive is bad. To test the motor I would hook
up a car battery to it, POSITVE lead to A1 NEGATIVE lead to F1
Install a jumper to connect A2 and F2 together and will turn one
direction, reverse the power cables on A1 and F1 and it will turn the
other direction although slower then at 50 volts.



Is the X and Y travel on this thing fed through one or separate
controller? That would seem to be a good way of checking where the
problem lies

jeff fired this volley in
:

Either way supply voltage out the controller + or - will enter the
armature go through the fields and then back to the controller causing
the armature to rotate. Pulse Width Modulation will control the speed
and torque of said motor.

No, I think you mis-read that.
He said there was 50V across the field, and ALSO 50V across the armature.

It's entirely possible for a drive to supply a steady-state voltage to
the field, and vary the armature voltage -- even to the point of
inverting the polarity of that second one.

Not all DC drives are "simple". I have a golf cart (personally) that
accepts DC from the battery into the (electronic) drive, and supplies +-V
(plus OR minus polarity) to the motor armature at full battery voltage
(without relays), and pulse-width-modulates the field at a single
polarity.

That provides both directions and variable speed without switches or
relays... from a 'single' 36V storage battery.

LLoyd


LLoyd

On Mon, 13 May 2013 21:45:50 -0400, jeff wrote:

On Mon, 13 May 2013 20:22:23 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

jeff fired this volley in
m:

Either way supply voltage out the controller + or - will enter the
armature go through the fields and then back to the controller causing
the armature to rotate. Pulse Width Modulation will control the speed
and torque of said motor.

No, I think you mis-read that.
He said there was 50V across the field, and ALSO 50V across the
armature.

**** I should have read it one more time, I missed across.... open
circuit.... Sorry


Likely, but you would have 50 volts across either one, open circuit or
not.

It's entirely possible for a drive to supply a steady-state voltage to
the field, and vary the armature voltage -- even to the point of
inverting the polarity of that second one.

Not all DC drives are "simple". I have a golf cart (personally) that
accepts DC from the battery into the (electronic) drive, and supplies +-V
(plus OR minus polarity) to the motor armature at full battery voltage
(without relays), and pulse-width-modulates the field at a single
polarity.

That provides both directions and variable speed without switches or
relays... from a 'single' 36V storage battery.

LLoyd


LLoyd

On 2013-05-14, jeff wrote:
On Sun, 12 May 2013 19:47:19 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

jeff fired this volley in
m:

Guess I can't help you then. Most dc motors I work on require
either two or four power leads. Waiting to see what you find.


Didn't read the post? It HAS two windings, and four leads. Two to
field, two to armature.

It just _happens_ that the field and armature power supplies share a
common. That does just occasionally happen in electrical stuff -- that
two supplies might share a common ground... even bipolar supplies are
usually ground-referenced.

Lloyd
Lloyd, I did read his post, several times in fact. I did not fire a
volley, one shot only, trying to hit the target.....

I am not trying to cause problems here, just trying to help where I
think I can as I do have experience in things DC albeit in the
forklift trade.

If I'm reading it correctly his motor sounds like any other dc motor
that is not a permanent magnet motor. It has a field winding F1 F2
and an armature with a commutator that brushs ride on A1 A2.

The fact that it only has three leads is what confuses me.

Actually -- the *motor* itself has your four terminals/wires,
A1, A2, F1 and F2.

The wiring from the driver/power-supply/WhatEverYouWantToCallIt
is three wires. One of them goes to one Armature terminal, one goes to
one Field terminal, and the third wire goes to both the remaining
Armature and Field terimnals. They're saving one wire, and tying
together one end of the Field and one end of the Armature power, a
common low voltage point for both.

Perhaps the currents are too high in the ones which you work on
to allow that sharing of leads. But his is not nearly that high a
power, and perhaps the distance from the motor to the supply is long
enough so it is worth while doing it that way.

Good Luck,
DoN.

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