Stepper motor controller help please

Guest
I recently acquired a programmable stepper motor controller. It was
made by Richmill Manufacturing Company Ltd. around 1982. It is
designed to drive a unipolar stepper motor. The guy I got it from said
it worked fine when he put it away and then upon trying it about a
year later it only works intermittently. I did discover one wire in
the cable that goes to the motor does not have continuity. This wire
is one of the two common wires that are the center taps of the motor
windings. I do not have the motor. I do not have a schematic and so
far have not been able to find one. I have not applied power to it
yet. It has a 3.6 volt ni-cad battery that is used for memory backup
and it needs to be replaced. I need advice about replacing
electrolytics. Though none are bulging they are old and have not had
power running through them for a long time. Should I just replace them
as a preventative measure? I have heard about "re-forming"
electrolytics. Should I even bother trying this? There are only about
10 ofthem so they would be cheap to replace. Another question is would
it be safe to try to power up and run the control without connecting a
stepper motor? Looking at the board it appears that 4 power
transistors switch rectified 50 volts AC to the motor coils. I thought
about just trying to turn the thing on and trying to program it and
see if it at least thinks it is doing something. Since I don't have
any large steppers I thought about connecting a 12 VDC 500 mA power
supply in lieu of the rectified 50 VAC to the circuit board and using
a small unipolar stepper to test the controller. Finally, what I would
like to do is connect the controller to a circuit that would convert
the unipolar switching signals to step and direction so that I can use
a Geckodrive servo amp and a servo motor. This way I can run whatever
size motor I want connected to an indexer that I am building.
Thanks,
Eric
 
etpm@whidbey.com wrote:

I recently acquired a programmable stepper motor controller. It was
made by Richmill Manufacturing Company Ltd. around 1982. It is
designed to drive a unipolar stepper motor. The guy I got it from said
it worked fine when he put it away and then upon trying it about a
year later it only works intermittently. I did discover one wire in
the cable that goes to the motor does not have continuity. This wire
is one of the two common wires that are the center taps of the motor
windings. I do not have the motor. I do not have a schematic and so
far have not been able to find one. I have not applied power to it
yet. It has a 3.6 volt ni-cad battery that is used for memory backup
and it needs to be replaced. I need advice about replacing
electrolytics. Though none are bulging they are old and have not had
power running through them for a long time. Should I just replace them
as a preventative measure? I have heard about "re-forming"
electrolytics. Should I even bother trying this? There are only about
10 ofthem so they would be cheap to replace. Another question is would
it be safe to try to power up and run the control without connecting a
stepper motor? Looking at the board it appears that 4 power
transistors switch rectified 50 volts AC to the motor coils. I thought
about just trying to turn the thing on and trying to program it and
see if it at least thinks it is doing something. Since I don't have
any large steppers I thought about connecting a 12 VDC 500 mA power
supply in lieu of the rectified 50 VAC to the circuit board and using
a small unipolar stepper to test the controller. Finally, what I would
like to do is connect the controller to a circuit that would convert
the unipolar switching signals to step and direction so that I can use
a Geckodrive servo amp and a servo motor. This way I can run whatever
size motor I want connected to an indexer that I am building.
Thanks,
Eric
powering it up with no motor should not be a problem.
Click to expand...

We use some sort of burden load if we don't have a motor to
test them. This is also where a 4 channel scope works well.

Jamie
 
On Thu, 28 Feb 2013 17:05:17 -0800, etpm@whidbey.com wrote:

I recently acquired a programmable stepper motor controller. It was
made by Richmill Manufacturing Company Ltd. around 1982. It is
designed to drive a unipolar stepper motor. The guy I got it from said
it worked fine when he put it away and then upon trying it about a
year later it only works intermittently. I did discover one wire in
the cable that goes to the motor does not have continuity. This wire
is one of the two common wires that are the center taps of the motor
windings. I do not have the motor. I do not have a schematic and so
far have not been able to find one. I have not applied power to it
yet. It has a 3.6 volt ni-cad battery that is used for memory backup
and it needs to be replaced. I need advice about replacing
electrolytics. Though none are bulging they are old and have not had
power running through them for a long time. Should I just replace them
as a preventative measure? I have heard about "re-forming"
electrolytics. Should I even bother trying this? There are only about
10 ofthem so they would be cheap to replace. Another question is would
it be safe to try to power up and run the control without connecting a
stepper motor? Looking at the board it appears that 4 power
transistors switch rectified 50 volts AC to the motor coils. I thought
about just trying to turn the thing on and trying to program it and
see if it at least thinks it is doing something. Since I don't have
any large steppers I thought about connecting a 12 VDC 500 mA power
supply in lieu of the rectified 50 VAC to the circuit board and using
a small unipolar stepper to test the controller. Finally, what I would
like to do is connect the controller to a circuit that would convert
the unipolar switching signals to step and direction so that I can use
a Geckodrive servo amp and a servo motor. This way I can run whatever
size motor I want connected to an indexer that I am building.
Thanks,
Eric
Click to expand...
Why not buy a modern USB stepper motor driver?


--

John Larkin Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation
 
On Thu, 28 Feb 2013 21:30:35 -0500, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

etpm@whidbey.com wrote:

I recently acquired a programmable stepper motor controller. It was
made by Richmill Manufacturing Company Ltd. around 1982. It is
designed to drive a unipolar stepper motor. The guy I got it from said
it worked fine when he put it away and then upon trying it about a
year later it only works intermittently. I did discover one wire in
the cable that goes to the motor does not have continuity. This wire
is one of the two common wires that are the center taps of the motor
windings. I do not have the motor. I do not have a schematic and so
far have not been able to find one. I have not applied power to it
yet. It has a 3.6 volt ni-cad battery that is used for memory backup
and it needs to be replaced. I need advice about replacing
electrolytics. Though none are bulging they are old and have not had
power running through them for a long time. Should I just replace them
as a preventative measure? I have heard about "re-forming"
electrolytics. Should I even bother trying this? There are only about
10 ofthem so they would be cheap to replace. Another question is would
it be safe to try to power up and run the control without connecting a
stepper motor? Looking at the board it appears that 4 power
transistors switch rectified 50 volts AC to the motor coils. I thought
about just trying to turn the thing on and trying to program it and
see if it at least thinks it is doing something. Since I don't have
any large steppers I thought about connecting a 12 VDC 500 mA power
supply in lieu of the rectified 50 VAC to the circuit board and using
a small unipolar stepper to test the controller. Finally, what I would
like to do is connect the controller to a circuit that would convert
the unipolar switching signals to step and direction so that I can use
a Geckodrive servo amp and a servo motor. This way I can run whatever
size motor I want connected to an indexer that I am building.
Thanks,
Eric
powering it up with no motor should not be a problem.

We use some sort of burden load if we don't have a motor to
test them. This is also where a 4 channel scope works well.

Jamie
Thanks for the reply Jamie. Do you think I should replace all the
Click to expand...
electrolytics just to be safe? If none are bulging and they test OK
with my $90.00 DVM do you think it is safe to leave them in?
Eric
 
On Fri, 01 Mar 2013 14:03:52 -0800, John Larkin
<jlarkin@highlandtechnology.com> wrote:

On Thu, 28 Feb 2013 17:05:17 -0800, etpm@whidbey.com wrote:

I recently acquired a programmable stepper motor controller. It was
made by Richmill Manufacturing Company Ltd. around 1982. It is
designed to drive a unipolar stepper motor. The guy I got it from said
it worked fine when he put it away and then upon trying it about a
year later it only works intermittently. I did discover one wire in
the cable that goes to the motor does not have continuity. This wire
is one of the two common wires that are the center taps of the motor
windings. I do not have the motor. I do not have a schematic and so
far have not been able to find one. I have not applied power to it
yet. It has a 3.6 volt ni-cad battery that is used for memory backup
and it needs to be replaced. I need advice about replacing
electrolytics. Though none are bulging they are old and have not had
power running through them for a long time. Should I just replace them
as a preventative measure? I have heard about "re-forming"
electrolytics. Should I even bother trying this? There are only about
10 ofthem so they would be cheap to replace. Another question is would
it be safe to try to power up and run the control without connecting a
stepper motor? Looking at the board it appears that 4 power
transistors switch rectified 50 volts AC to the motor coils. I thought
about just trying to turn the thing on and trying to program it and
see if it at least thinks it is doing something. Since I don't have
any large steppers I thought about connecting a 12 VDC 500 mA power
supply in lieu of the rectified 50 VAC to the circuit board and using
a small unipolar stepper to test the controller. Finally, what I would
like to do is connect the controller to a circuit that would convert
the unipolar switching signals to step and direction so that I can use
a Geckodrive servo amp and a servo motor. This way I can run whatever
size motor I want connected to an indexer that I am building.
Thanks,
Eric

Why not buy a modern USB stepper motor driver?
Greetings John,
Click to expand...
This controller is a programmable controller meant to be interfaced
with a CNC machine tool. So the controller is programmed to make
certain rotary moves when the CNC machine asks it to with an M code.
After finishing the program it sends a signal back to the CNC that is
is finished and the CNC continues with its program. I would rather not
buy a NEMA size 34 stepper when I already have servos and servo amps
slated for use in an indexer I'm building. So this programmable device
came along which will save me the time of building one with an
Arduino. If it works.
Eric
 
etpm@whidbey.com wrote:
On Thu, 28 Feb 2013 21:30:35 -0500, Jamie
jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:


etpm@whidbey.com wrote:


I recently acquired a programmable stepper motor controller. It was
made by Richmill Manufacturing Company Ltd. around 1982. It is
designed to drive a unipolar stepper motor. The guy I got it from said
it worked fine when he put it away and then upon trying it about a
year later it only works intermittently. I did discover one wire in
the cable that goes to the motor does not have continuity. This wire
is one of the two common wires that are the center taps of the motor
windings. I do not have the motor. I do not have a schematic and so
far have not been able to find one. I have not applied power to it
yet. It has a 3.6 volt ni-cad battery that is used for memory backup
and it needs to be replaced. I need advice about replacing
electrolytics. Though none are bulging they are old and have not had
power running through them for a long time. Should I just replace them
as a preventative measure? I have heard about "re-forming"
electrolytics. Should I even bother trying this? There are only about
10 ofthem so they would be cheap to replace. Another question is would
it be safe to try to power up and run the control without connecting a
stepper motor? Looking at the board it appears that 4 power
transistors switch rectified 50 volts AC to the motor coils. I thought
about just trying to turn the thing on and trying to program it and
see if it at least thinks it is doing something. Since I don't have
any large steppers I thought about connecting a 12 VDC 500 mA power
supply in lieu of the rectified 50 VAC to the circuit board and using
a small unipolar stepper to test the controller. Finally, what I would
like to do is connect the controller to a circuit that would convert
the unipolar switching signals to step and direction so that I can use
a Geckodrive servo amp and a servo motor. This way I can run whatever
size motor I want connected to an indexer that I am building.
Thanks,
Eric

powering it up with no motor should not be a problem.

We use some sort of burden load if we don't have a motor to
test them. This is also where a 4 channel scope works well.

Jamie

Thanks for the reply Jamie. Do you think I should replace all the
electrolytics just to be safe? If none are bulging and they test OK
with my $90.00 DVM do you think it is safe to leave them in?
Click to expand...
It depends on what kind of drive system it is. If you have a
ESR meter you could check them for high R, which is common in aged
caps and if the circuit depends on low ESR you could introduce unwanted
noise in the output or maybe even fail under load.

Unless your meter has a ESR/D function on it, it would be hard to
determine this. Of course many of us like to pump a square wave into a
cap and measure the drop across a known R feeding the DUP (device under
test), which would be the cap. The idea is to measure the initial
charge point at the start of the square wave to calculate the level of
volts detected and perform some math to determine the effective Series
resistance in the cap. Caps do not have absolute 0 ohms at the initial
state of charge of a fully drained cap.

If this is going to be for you're own personal use, I wouldn't bother
replacing them if they appear to be ok via a standard cap test. If you
have plans to sell it, I may consider doing so.

Jamie
 
<SNIP>
Thanks for the reply Jamie. Do you think I should replace all the
electrolytics just to be safe? If none are bulging and they test OK
with my $90.00 DVM do you think it is safe to leave them in?


It depends on what kind of drive system it is. If you have a
ESR meter you could check them for high R, which is common in aged
caps and if the circuit depends on low ESR you could introduce unwanted
noise in the output or maybe even fail under load.

Unless your meter has a ESR/D function on it, it would be hard to
determine this. Of course many of us like to pump a square wave into a
cap and measure the drop across a known R feeding the DUP (device under
test), which would be the cap. The idea is to measure the initial
charge point at the start of the square wave to calculate the level of
volts detected and perform some math to determine the effective Series
resistance in the cap. Caps do not have absolute 0 ohms at the initial
state of charge of a fully drained cap.

If this is going to be for you're own personal use, I wouldn't bother
replacing them if they appear to be ok via a standard cap test. If you
have plans to sell it, I may consider doing so.

Jamie


My meter just measures capacitance. The reason I'm worried about the
Click to expand...
caps is that if one is bad could it destroy something like the EPROM
which holds the operating system of the controller. But if that's not
something I need to worry about I'll just power it up and see if it
sends pulses to where and when I think it should. If that tests out OK
then I need a circuit that will convert the unipolar stepping sequence
into step and direction. I could probably figure out how to do this
myself, and maybe I should for the learning experience. But I do have
a job coming up that would benefit from using this programmable
controller.
Eric
 
etpm@whidbey.com wrote:

SNIP

Thanks for the reply Jamie. Do you think I should replace all the
electrolytics just to be safe? If none are bulging and they test OK
with my $90.00 DVM do you think it is safe to leave them in?


It depends on what kind of drive system it is. If you have a
ESR meter you could check them for high R, which is common in aged
caps and if the circuit depends on low ESR you could introduce unwanted
noise in the output or maybe even fail under load.

Unless your meter has a ESR/D function on it, it would be hard to
determine this. Of course many of us like to pump a square wave into a
cap and measure the drop across a known R feeding the DUP (device under
test), which would be the cap. The idea is to measure the initial
charge point at the start of the square wave to calculate the level of
volts detected and perform some math to determine the effective Series
resistance in the cap. Caps do not have absolute 0 ohms at the initial
state of charge of a fully drained cap.

If this is going to be for you're own personal use, I wouldn't bother
replacing them if they appear to be ok via a standard cap test. If you
have plans to sell it, I may consider doing so.

Jamie



My meter just measures capacitance. The reason I'm worried about the
caps is that if one is bad could it destroy something like the EPROM
which holds the operating system of the controller. But if that's not
something I need to worry about I'll just power it up and see if it
sends pulses to where and when I think it should. If that tests out OK
then I need a circuit that will convert the unipolar stepping sequence
into step and direction. I could probably figure out how to do this
myself, and maybe I should for the learning experience. But I do have
a job coming up that would benefit from using this programmable
controller.
Eric
Click to expand...
Just put the two on separate power and drive it with an isolated device.

You should be doing that anyway to make sure you don't get any high
potential coming back into sensitive circuitry.

Jamie
 
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