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Stepper motor controller help please

Started by Unknown February 28, 2013
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. 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
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 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, 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? >
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 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
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