3 pole DC motor failure mode?

[N_Cook]

Or internalised self destruction of one pair of drivers and nothing to do
with motor playing up?
Motor supply is 33V and 3 amp fuse , main drive motor for a photocopier, 3
poles and magnets. I have a parts mule for this copier but do not want to
take all the frame apart to change the motor unnecessarily, the driver board
is easy to get to.
Other than lubricate the motor bearings and change the
driver+speed/direction processing board over , anything else to check?
Both motors measure 1.5 ohms all 3 ways between coils , also inside is 3 off
4 pin, presumably hall effect devices, can only see the pins. The
electronics is for speed control, direction and braking. One pair of NPN+PNP
TO220 drivers , 3 pairs in all, is all-pin shorted , well 1 to 3 ohm. Failed
at switch on , knocking out fuses , no overheating or odd noises/smoke etc,
Of course may have failed at final braking of the motor at last useage but
as presumably braking is once per sheet cycle as not used for batch copying,
seems unlikely it would happen to fail on the last of dozens of sheets

 

[Phil Allison]

"Nutcase Kook"

Or internalised self destruction of one pair of drivers and nothing to do
with motor playing up?
Motor supply is 33V and 3 amp fuse ....

** There is no way a 3 pole DC motor can handle 33V and survive.

6V is normal, 9V at most.

All got to do with arcing across the contacts on the comm.



.... Phil

 

[N_Cook]

Maybe something to do with lack of lubrication, seems to run quiter now,
perhaps a bearing stuck enough for overload. Seems to turn, by finger
,easier than before.
Decided to solder 3 tell-tale small 28V bulbs to each coil and ground and
power up with changed board. Overdriven by 33V at power up and half
brightness but balanced in operation.
3 coil ,36 degree stepper motor rather than DC motor to be more exact. Will
power up a few more times and then remove the telltales
The hall-effect presumably for phase monitoring and an external 12 vane
interupted slotted opto for speed and a PTO solenoid clutch to transfer
power presumably at the right operational speed. Must vary that speed for
different size paper and magnification. Anyone know where the braking
fusnction comes in? perhaps the PTO system will not disengage reliably at
speed and operational torque.

 

[Jamie]

N_Cook wrote:

Maybe something to do with lack of lubrication, seems to run quiter now,
perhaps a bearing stuck enough for overload. Seems to turn, by finger
,easier than before.
Decided to solder 3 tell-tale small 28V bulbs to each coil and ground and
power up with changed board. Overdriven by 33V at power up and half
brightness but balanced in operation.
3 coil ,36 degree stepper motor rather than DC motor to be more exact. Will
power up a few more times and then remove the telltales
The hall-effect presumably for phase monitoring and an external 12 vane
interupted slotted opto for speed and a PTO solenoid clutch to transfer
power presumably at the right operational speed. Must vary that speed for
different size paper and magnification. Anyone know where the braking
fusnction comes in? perhaps the PTO system will not disengage reliably at
speed and operational torque.


If that truly is a stepper motor, the motor is the braking function.

It simply keeps the last step phase energized. And being a stepper
motor, you'll have either 4 or 6 wires and maybe a ground wire.

I would be willing to bet you have a servo motor there. If so, it
most likely would have 3 wires in it and an internal feed back system.
It could also have a mechanical brake, too. But I would venture to say
the servo drive electronics is locking the motor in place as a function
of brake.

Jamie

 

[Phil Hobbs]

Jamie wrote:

N_Cook wrote:

Maybe something to do with lack of lubrication, seems to run quiter now,
perhaps a bearing stuck enough for overload. Seems to turn, by finger
,easier than before.
Decided to solder 3 tell-tale small 28V bulbs to each coil and ground and
power up with changed board. Overdriven by 33V at power up and half
brightness but balanced in operation.
3 coil ,36 degree stepper motor rather than DC motor to be more exact. Will
power up a few more times and then remove the telltales
The hall-effect presumably for phase monitoring and an external 12 vane
interupted slotted opto for speed and a PTO solenoid clutch to transfer
power presumably at the right operational speed. Must vary that speed for
different size paper and magnification. Anyone know where the braking
fusnction comes in? perhaps the PTO system will not disengage reliably at
speed and operational torque.


If that truly is a stepper motor, the motor is the braking function.
It simply keeps the last step phase energized. And being a stepper
motor, you'll have either 4 or 6 wires and maybe a ground wire.

I would be willing to bet you have a servo motor there. If so, it
most likely would have 3 wires in it and an internal feed back system.
It could also have a mechanical brake, too. But I would venture to say
the servo drive electronics is locking the motor in place as a function
of brake.

Jamie

Anybody using a stepper as the only brake in the system had better not
be holding any significant weight against gravity. A stepper that's
lost sync might as well not even be there. Whatever that load is, one
day it's _going_ to fall.

Cheers

Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

 

[N_Cook]

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote in message
news:4F9C9ECF.3FD13B0A@electrooptical.net...

Jamie wrote:

N_Cook wrote:

Maybe something to do with lack of lubrication, seems to run quiter
now,
perhaps a bearing stuck enough for overload. Seems to turn, by finger
,easier than before.
Decided to solder 3 tell-tale small 28V bulbs to each coil and ground
and
power up with changed board. Overdriven by 33V at power up and half
brightness but balanced in operation.
3 coil ,36 degree stepper motor rather than DC motor to be more exact.
Will
power up a few more times and then remove the telltales
The hall-effect presumably for phase monitoring and an external 12
vane
interupted slotted opto for speed and a PTO solenoid clutch to
transfer
power presumably at the right operational speed. Must vary that speed
for
different size paper and magnification. Anyone know where the braking
fusnction comes in? perhaps the PTO system will not disengage reliably
at
speed and operational torque.


If that truly is a stepper motor, the motor is the braking function.
It simply keeps the last step phase energized. And being a stepper
motor, you'll have either 4 or 6 wires and maybe a ground wire.

I would be willing to bet you have a servo motor there. If so, it
most likely would have 3 wires in it and an internal feed back system.
It could also have a mechanical brake, too. But I would venture to say
the servo drive electronics is locking the motor in place as a function
of brake.

Jamie

Anybody using a stepper as the only brake in the system had better not
be holding any significant weight against gravity. A stepper that's
lost sync might as well not even be there. Whatever that load is, one
day it's _going_ to fall.

Cheers

Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

If there is no binding of bearings etc there should be no load to speak of.
It just turns the OPC drum and some rollers that feed paper through the
system. The main load is probably the fuser roller as it is pushed against a
backing roller to fuse the toner into the paper. Worst normal situation
would be scrunched up paper jamming in the fuser section

 

[N_Cook]

Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in message
news:Tx%mr.167138$KQ2.92589@newsfe15.iad...

N_Cook wrote:

Maybe something to do with lack of lubrication, seems to run quiter now,
perhaps a bearing stuck enough for overload. Seems to turn, by finger
,easier than before.
Decided to solder 3 tell-tale small 28V bulbs to each coil and ground
and
power up with changed board. Overdriven by 33V at power up and half
brightness but balanced in operation.
3 coil ,36 degree stepper motor rather than DC motor to be more exact.
Will
power up a few more times and then remove the telltales
The hall-effect presumably for phase monitoring and an external 12 vane
interupted slotted opto for speed and a PTO solenoid clutch to transfer
power presumably at the right operational speed. Must vary that speed
for
different size paper and magnification. Anyone know where the braking
fusnction comes in? perhaps the PTO system will not disengage reliably
at
speed and operational torque.


If that truly is a stepper motor, the motor is the braking function.
It simply keeps the last step phase energized. And being a stepper
motor, you'll have either 4 or 6 wires and maybe a ground wire.

I would be willing to bet you have a servo motor there. If so, it
most likely would have 3 wires in it and an internal feed back system.
It could also have a mechanical brake, too. But I would venture to say
the servo drive electronics is locking the motor in place as a function
of brake.

Jamie

I could not divide 360 by 12, it is 30 degree steps and turning by hand it
has a stepper motor feel against the magnets and 12 magnetic steps. Ground
is mechanical to the frame if any ground. 11 wires 3 are related to the
coils, 1.5R between each to the other leaving 8 ,
the 3 hall effect have one common I could detect by probing with a needle,
probably one other in common leaving 2 for each sensing part of the Halls.
Separately there is a slotted opto.
Without scoping or strobing or something I cannot tell whether PTO is
coincident with starting or stopping. When I had the tell-tales in there
(from common collector of each driver pair to ground)
bright at startup, half bright for motor run , then off or too low a voltage
to light the lamps for half a second then a second of half bright. Perhaps
the bulbs off is the braking stage.
In normal operation you see the axial fan which is directly coupled to this
motor , ie not via PTO, kicks back before stopping.
The motor control chippery is TC9192P, TA75358, NEC uPC494C, TA7712 and a
4013

 

[Phil Hobbs]

N_Cook wrote:

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote in message
news:4F9C9ECF.3FD13B0A@electrooptical.net...
Jamie wrote:

N_Cook wrote:

Maybe something to do with lack of lubrication, seems to run quiter
now,
perhaps a bearing stuck enough for overload. Seems to turn, by finger
,easier than before.
Decided to solder 3 tell-tale small 28V bulbs to each coil and ground
and
power up with changed board. Overdriven by 33V at power up and half
brightness but balanced in operation.
3 coil ,36 degree stepper motor rather than DC motor to be more exact.
Will
power up a few more times and then remove the telltales
The hall-effect presumably for phase monitoring and an external 12
vane
interupted slotted opto for speed and a PTO solenoid clutch to
transfer
power presumably at the right operational speed. Must vary that speed
for
different size paper and magnification. Anyone know where the braking
fusnction comes in? perhaps the PTO system will not disengage reliably
at
speed and operational torque.


If that truly is a stepper motor, the motor is the braking function.
It simply keeps the last step phase energized. And being a stepper
motor, you'll have either 4 or 6 wires and maybe a ground wire.

I would be willing to bet you have a servo motor there. If so, it
most likely would have 3 wires in it and an internal feed back system.
It could also have a mechanical brake, too. But I would venture to say
the servo drive electronics is locking the motor in place as a function
of brake.

Jamie

Anybody using a stepper as the only brake in the system had better not
be holding any significant weight against gravity. A stepper that's
lost sync might as well not even be there. Whatever that load is, one
day it's _going_ to fall.



If there is no binding of bearings etc there should be no load to speak of.
It just turns the OPC drum and some rollers that feed paper through the
system. The main load is probably the fuser roller as it is pushed against a
backing roller to fuse the toner into the paper. Worst normal situation
would be scrunched up paper jamming in the fuser section

Sure, in a printer or something there's no big problem...over in the
design group we've been having an argument about the applicability of
steppers, and how their apparent simplicity and reliability is mostly an
illusion, so it's sort of on the top of my mind just now. People have
gotten killed by systems with steppers and no fail-safe brake.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

 

[Jamie]

N_Cook wrote:

Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in message
news:Tx%mr.167138$KQ2.92589@newsfe15.iad...

N_Cook wrote:


Maybe something to do with lack of lubrication, seems to run quiter now,
perhaps a bearing stuck enough for overload. Seems to turn, by finger
,easier than before.
Decided to solder 3 tell-tale small 28V bulbs to each coil and ground

and

power up with changed board. Overdriven by 33V at power up and half
brightness but balanced in operation.
3 coil ,36 degree stepper motor rather than DC motor to be more exact.

Will

power up a few more times and then remove the telltales
The hall-effect presumably for phase monitoring and an external 12 vane
interupted slotted opto for speed and a PTO solenoid clutch to transfer
power presumably at the right operational speed. Must vary that speed

for

different size paper and magnification. Anyone know where the braking
fusnction comes in? perhaps the PTO system will not disengage reliably

at

speed and operational torque.



If that truly is a stepper motor, the motor is the braking function.
It simply keeps the last step phase energized. And being a stepper
motor, you'll have either 4 or 6 wires and maybe a ground wire.

I would be willing to bet you have a servo motor there. If so, it
most likely would have 3 wires in it and an internal feed back system.
It could also have a mechanical brake, too. But I would venture to say
the servo drive electronics is locking the motor in place as a function
of brake.

Jamie



I could not divide 360 by 12, it is 30 degree steps and turning by hand it
has a stepper motor feel against the magnets and 12 magnetic steps. Ground
is mechanical to the frame if any ground. 11 wires 3 are related to the
coils, 1.5R between each to the other leaving 8 ,
the 3 hall effect have one common I could detect by probing with a needle,
probably one other in common leaving 2 for each sensing part of the Halls.
Separately there is a slotted opto.
Without scoping or strobing or something I cannot tell whether PTO is
coincident with starting or stopping. When I had the tell-tales in there
(from common collector of each driver pair to ground)
bright at startup, half bright for motor run , then off or too low a voltage
to light the lamps for half a second then a second of half bright. Perhaps
the bulbs off is the braking stage.
In normal operation you see the axial fan which is directly coupled to this
motor , ie not via PTO, kicks back before stopping.
The motor control chippery is TC9192P, TA75358, NEC uPC494C, TA7712 and a
4013



That is a 3 phase servo/synchronous DC brushless motor.

Made pretty much the same way as your basic cooling fans with extra
feed back to be able to lock rotor and slowly turn either direction to
keep a lock.

These motors work very nicely in regards to holding things in position.

It's possible you have a 12 pole motor which would make it not the
fastest motor but give you some torque and tight tracking.

That first chip in the list is a Phase lock Loop controller that can
handle 2 motors.

The nice thing about these motors is due to the integrated feed back
which has to be mechanically position correctly so the controller knows
exactly where the rotor is in relation to the poles.


Jamie

 

[N_Cook]

Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in message
news:jQcnr.13563$em4.6205@newsfe21.iad...

N_Cook wrote:

Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in
message
news:Tx%mr.167138$KQ2.92589@newsfe15.iad...

N_Cook wrote:


Maybe something to do with lack of lubrication, seems to run quiter
now,
perhaps a bearing stuck enough for overload. Seems to turn, by finger
,easier than before.
Decided to solder 3 tell-tale small 28V bulbs to each coil and ground

and

power up with changed board. Overdriven by 33V at power up and half
brightness but balanced in operation.
3 coil ,36 degree stepper motor rather than DC motor to be more exact.

Will

power up a few more times and then remove the telltales
The hall-effect presumably for phase monitoring and an external 12 vane
interupted slotted opto for speed and a PTO solenoid clutch to transfer
power presumably at the right operational speed. Must vary that speed

for

different size paper and magnification. Anyone know where the braking
fusnction comes in? perhaps the PTO system will not disengage reliably

at

speed and operational torque.



If that truly is a stepper motor, the motor is the braking function.
It simply keeps the last step phase energized. And being a stepper
motor, you'll have either 4 or 6 wires and maybe a ground wire.

I would be willing to bet you have a servo motor there. If so, it
most likely would have 3 wires in it and an internal feed back system.
It could also have a mechanical brake, too. But I would venture to say
the servo drive electronics is locking the motor in place as a function
of brake.

Jamie



I could not divide 360 by 12, it is 30 degree steps and turning by hand
it
has a stepper motor feel against the magnets and 12 magnetic steps.
Ground
is mechanical to the frame if any ground. 11 wires 3 are related to the
coils, 1.5R between each to the other leaving 8 ,
the 3 hall effect have one common I could detect by probing with a
needle,
probably one other in common leaving 2 for each sensing part of the
Halls.
Separately there is a slotted opto.
Without scoping or strobing or something I cannot tell whether PTO is
coincident with starting or stopping. When I had the tell-tales in there
(from common collector of each driver pair to ground)
bright at startup, half bright for motor run , then off or too low a
voltage
to light the lamps for half a second then a second of half bright.
Perhaps
the bulbs off is the braking stage.
In normal operation you see the axial fan which is directly coupled to
this
motor , ie not via PTO, kicks back before stopping.
The motor control chippery is TC9192P, TA75358, NEC uPC494C, TA7712 and
a
4013



That is a 3 phase servo/synchronous DC brushless motor.

Made pretty much the same way as your basic cooling fans with extra
feed back to be able to lock rotor and slowly turn either direction to
keep a lock.

These motors work very nicely in regards to holding things in position.

It's possible you have a 12 pole motor which would make it not the
fastest motor but give you some torque and tight tracking.

That first chip in the list is a Phase lock Loop controller that can
handle 2 motors.

The nice thing about these motors is due to the integrated feed back
which has to be mechanically position correctly so the controller knows
exactly where the rotor is in relation to the poles.


Jamie

Are you saying there could be microstepping involved, not perhaps with a
copier but if that sort of motor was used in a plotter say

 

[Jamie]

N_Cook wrote:

Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in message
news:jQcnr.13563$em4.6205@newsfe21.iad...

N_Cook wrote:


Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in

message

news:Tx%mr.167138$KQ2.92589@newsfe15.iad...


N_Cook wrote:



Maybe something to do with lack of lubrication, seems to run quiter

now,

perhaps a bearing stuck enough for overload. Seems to turn, by finger
,easier than before.
Decided to solder 3 tell-tale small 28V bulbs to each coil and ground

and


power up with changed board. Overdriven by 33V at power up and half
brightness but balanced in operation.
3 coil ,36 degree stepper motor rather than DC motor to be more exact.

Will


power up a few more times and then remove the telltales
The hall-effect presumably for phase monitoring and an external 12 vane
interupted slotted opto for speed and a PTO solenoid clutch to transfer
power presumably at the right operational speed. Must vary that speed

for


different size paper and magnification. Anyone know where the braking
fusnction comes in? perhaps the PTO system will not disengage reliably

at


speed and operational torque.



If that truly is a stepper motor, the motor is the braking function.
It simply keeps the last step phase energized. And being a stepper
motor, you'll have either 4 or 6 wires and maybe a ground wire.

I would be willing to bet you have a servo motor there. If so, it
most likely would have 3 wires in it and an internal feed back system.
It could also have a mechanical brake, too. But I would venture to say
the servo drive electronics is locking the motor in place as a function
of brake.

Jamie



I could not divide 360 by 12, it is 30 degree steps and turning by hand

it

has a stepper motor feel against the magnets and 12 magnetic steps.

Ground

is mechanical to the frame if any ground. 11 wires 3 are related to the
coils, 1.5R between each to the other leaving 8 ,
the 3 hall effect have one common I could detect by probing with a

needle,

probably one other in common leaving 2 for each sensing part of the

Halls.

Separately there is a slotted opto.
Without scoping or strobing or something I cannot tell whether PTO is
coincident with starting or stopping. When I had the tell-tales in there
(from common collector of each driver pair to ground)
bright at startup, half bright for motor run , then off or too low a

voltage

to light the lamps for half a second then a second of half bright.

Perhaps

the bulbs off is the braking stage.
In normal operation you see the axial fan which is directly coupled to

this

motor , ie not via PTO, kicks back before stopping.
The motor control chippery is TC9192P, TA75358, NEC uPC494C, TA7712 and

a

4013




That is a 3 phase servo/synchronous DC brushless motor.

Made pretty much the same way as your basic cooling fans with extra
feed back to be able to lock rotor and slowly turn either direction to
keep a lock.

These motors work very nicely in regards to holding things in position.

It's possible you have a 12 pole motor which would make it not the
fastest motor but give you some torque and tight tracking.

That first chip in the list is a Phase lock Loop controller that can
handle 2 motors.

The nice thing about these motors is due to the integrated feed back
which has to be mechanically position correctly so the controller knows
exactly where the rotor is in relation to the poles.


Jamie




Are you saying there could be microstepping involved, not perhaps with a
copier but if that sort of motor was used in a plotter say


There are different types of feed back systems and you must have the

correct drive electronics per motor.

One of the most common ones I can think of that we use at work is
that using a A+B and Z channel.
The A+B can be used for both, direction detection and position. The Z
is a index pulse and in the case of that motor, it could be at the
corner of each pole. Or, it could be just one rotation and the driver
just knows the number of poles there are and the PPR count and does the
count after initial rotation.

Some systems simply generate a gray code which works very nicely too!
In your case, it could be a 3 bit code which gives you an absolute
position of rotor per pole. The 3 bit code should yield a combination of
8 places. Put that together with a 12 pole motor and you can have 96
positions for holding index. That's strange, that almost looks like the
Font size per inch in windows by default!

You see the problem with using a 3 phase system like that for
positioning and hold, the torque changes on the rotor are depending on
what position of the pole you're in. So, it is common for a drive
electronics to bias the drive to over come jitters between the poles and
to do this, it needs to know exactly where the poles with relation to
the PM is.

You said you had R's in the coils? that tells me the Q has been
lowered so less ringing will develop, maybe.

Jamie

 

[N_Cook]

Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in message
news:Jiknr.8$1R4.1@newsfe17.iad...

N_Cook wrote:
Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in
message
news:jQcnr.13563$em4.6205@newsfe21.iad...

N_Cook wrote:


Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in

message

news:Tx%mr.167138$KQ2.92589@newsfe15.iad...


N_Cook wrote:



Maybe something to do with lack of lubrication, seems to run quiter

now,

perhaps a bearing stuck enough for overload. Seems to turn, by finger
,easier than before.
Decided to solder 3 tell-tale small 28V bulbs to each coil and ground

and


power up with changed board. Overdriven by 33V at power up and half
brightness but balanced in operation.
3 coil ,36 degree stepper motor rather than DC motor to be more
exact.

Will


power up a few more times and then remove the telltales
The hall-effect presumably for phase monitoring and an external 12
vane
interupted slotted opto for speed and a PTO solenoid clutch to
transfer
power presumably at the right operational speed. Must vary that speed

for


different size paper and magnification. Anyone know where the braking
fusnction comes in? perhaps the PTO system will not disengage
reliably

at


speed and operational torque.



If that truly is a stepper motor, the motor is the braking function.
It simply keeps the last step phase energized. And being a stepper
motor, you'll have either 4 or 6 wires and maybe a ground wire.

I would be willing to bet you have a servo motor there. If so, it
most likely would have 3 wires in it and an internal feed back system.
It could also have a mechanical brake, too. But I would venture to say
the servo drive electronics is locking the motor in place as a
function
of brake.

Jamie



I could not divide 360 by 12, it is 30 degree steps and turning by hand

it

has a stepper motor feel against the magnets and 12 magnetic steps.

Ground

is mechanical to the frame if any ground. 11 wires 3 are related to the
coils, 1.5R between each to the other leaving 8 ,
the 3 hall effect have one common I could detect by probing with a

needle,

probably one other in common leaving 2 for each sensing part of the

Halls.

Separately there is a slotted opto.
Without scoping or strobing or something I cannot tell whether PTO is
coincident with starting or stopping. When I had the tell-tales in
there
(from common collector of each driver pair to ground)
bright at startup, half bright for motor run , then off or too low a

voltage

to light the lamps for half a second then a second of half bright.

Perhaps

the bulbs off is the braking stage.
In normal operation you see the axial fan which is directly coupled to

this

motor , ie not via PTO, kicks back before stopping.
The motor control chippery is TC9192P, TA75358, NEC uPC494C, TA7712 and

a

4013




That is a 3 phase servo/synchronous DC brushless motor.

Made pretty much the same way as your basic cooling fans with extra
feed back to be able to lock rotor and slowly turn either direction to
keep a lock.

These motors work very nicely in regards to holding things in
position.

It's possible you have a 12 pole motor which would make it not the
fastest motor but give you some torque and tight tracking.

That first chip in the list is a Phase lock Loop controller that can
handle 2 motors.

The nice thing about these motors is due to the integrated feed back
which has to be mechanically position correctly so the controller knows
exactly where the rotor is in relation to the poles.


Jamie




Are you saying there could be microstepping involved, not perhaps with a
copier but if that sort of motor was used in a plotter say


There are different types of feed back systems and you must have the
correct drive electronics per motor.

One of the most common ones I can think of that we use at work is
that using a A+B and Z channel.
The A+B can be used for both, direction detection and position. The Z
is a index pulse and in the case of that motor, it could be at the
corner of each pole. Or, it could be just one rotation and the driver
just knows the number of poles there are and the PPR count and does the
count after initial rotation.

Some systems simply generate a gray code which works very nicely too!
In your case, it could be a 3 bit code which gives you an absolute
position of rotor per pole. The 3 bit code should yield a combination of
8 places. Put that together with a 12 pole motor and you can have 96
positions for holding index. That's strange, that almost looks like the
Font size per inch in windows by default!

You see the problem with using a 3 phase system like that for
positioning and hold, the torque changes on the rotor are depending on
what position of the pole you're in. So, it is common for a drive
electronics to bias the drive to over come jitters between the poles and
to do this, it needs to know exactly where the poles with relation to
the PM is.

You said you had R's in the coils? that tells me the Q has been
lowered so less ringing will develop, maybe.

Jamie

With this copier there is paper size selection from A5 to A3 nut more
interestingly reduction or magnification from 64 percent to 154 percent by 1
percent steps, so need some pretty precise control of speed. I always
thought it was feather action microswitches that set other parts of the
operation as paper goes through the machine but they may be for timeout
error determination and the real sequence process timing done via the
hall-effects and slotted opto/vane system around the motor
The motor is this, from the stock number, but no technical info known about
the internals/specs
http://www.eatik.org/index.php?page=shop.product_details&category_id=0&flypa
ge=flypage-ask.tpl&product_id=218&option=com_virtuemart&Itemid=1