View Full Version : Looking for some motor specs

10-27-2003, 03:03 AM
Not sure if this is the right place to post this but didn't seam to fit any where else.

Any way,I have 3 steppers that I bought over a year ago. I have just moved and can't find the documentation. I have tried emailing the company that made them but they said they can't help. I have tried google (plus about 15 other search engines) and I have a email in to the company that I bought them from.

The specs that I do know are:
1.8 deg/step
made by Shinano Kenshi
part numbers 127k93840 and sth-54d302
the motor has 5 wires. red, green, white (common), blue, Orange

any more info would be good. I'm looking to wiring pin-out and torq.


10-27-2003, 07:56 PM
Hi, the actual pinouts or wire numbers are not important, it's the order they are in that is.

To find out this order connect the common white lead to (V+) 7.8V, then connect any other lead to ground (-), call this lead number (4). Lets say you have connected WHITE (common), and RED (4). Leave both these wires connected throughout the rest of the process.

Now connect any other wire to ground (-), let's say the green one. If the motor turns a small increment clockwise, call it number (3), for anticlockwise call it (1), if nothing happens call it (2). Assign the appropriate number to the green wire and disconnect the green wire.

repeat the above paragraph for the remaining coloured wires.

You should now have a "Firing order" for your stepper motor. Much like a car engine, it doesn't matter what number you call the cylnders, if you fire them in the right order the engine will run.

Hope this helps...

Mariss Freimanis
10-27-2003, 09:18 PM
5-wire steppers are kind of a bummer because they cannot be used with modern, switching-type bipolar drives. 4, 6 and 8-wire motors can be, but not 5-wire motors. You can only use an R/L drive with it.


10-28-2003, 06:59 PM
I was under the impression that pulse width modulation could be used on 5 wire steppers and not just L/R drives.

Also that 5 wire steppers can be run as Bi-Polar by leaving the centre taps unconnected.

Not only that, but 5 wire unipolars can be run in either hi-torque bi-polar mode, centre taps unconnected. Or they can be run in high speed bi-polar mode by using the centre taps and one half of each coil, ignoring the 2 wires of each other coil half. Higher speed is achieved due to lower inductance, but at the cost of torque.


Mariss Freimanis
10-28-2003, 11:42 PM
You may be confusing 0.72 degree per step 5-phase step motors with 1.8 degree 2-phase step motors having a common center tap.

2-phase step motors require 2 coils, so that's 4 wires. If each winding is center-tapped and these taps are brought out, you have a 6-wire stepper.

If, sadly, these center-taps are internally connected and the resulting common is brought out, you have a 5-wire 2-phase motor that is usable only with an L/R drive.

It cannot be used with any high performance drive because of the interconnection between windings. A manufacturer that does this to a motor just to save the cost of a single wire should be covered with honey and be staked out over an anthill.


10-29-2003, 01:09 AM
Thanks for the info MrBean. That was the main problem I was having, just couldn't get the motor to turn right know matter how I hooked the wires up. Got them working thanks.

Not sure what a L/R driver is but I'm using a homebuilt driver board called a Piker 3x from John Kleinbauer's web-site. Not sure if he still has the schematic up. I got the schematic with the set of plans that I bought from him.

The driver board just uses basic step/dir commands from the printer port. Nothing fancy. Output transistors are tip120.

Thanks again for the info. Hope to have my machine up and running soon.

10-29-2003, 06:38 PM

Surely a 5 wire unipolar is a Bipolar if you ignore the common centre tap. As such, this can be used with the drives you refer to. See diagram.

A 5 wire uni cannot be run in high-speed bipolar mode, but the 6 wire ones can.

I'm still learning this stuff, so correct me if the diagram is wrong, and if so, why can't the 5 wire unipolar be ran as a bipolar.

Thanks for your comments.

10-29-2003, 06:48 PM
Hey, who nicked the picture? Was working a minute ago.


bugger, it happened again. Sorry.

10-29-2003, 06:57 PM
I apologize for hijacking this thread but the damn picture posts in the test forum. Look honest...

I promise this is the last try......

Bugger, and again....

Oh well....

10-29-2003, 11:43 PM
LOL looks like its working now. :-)

Mariss Freimanis
10-30-2003, 10:14 AM
The killer is the common center tap between the windings if the motor is run on a bipolar switching drive. Current that should not will flow between windings.

You can prove it to yourself by running a 6-wire motor using the end wires. Set a multimeter to AC volts and place it across the center taps. If you read a voltage, current will flow should you short the center-taps together.