Help me identifing the Wires of Steppers

[Khalid]

Okay, Here are the Two Motors I found from EPSON Printer.. I got them from Printer Repair Shop for $6US.. One is Bipolar 3.7 degree/Step and Other is Unipolar with 1.8 degree/Step..

I didn't found the complete specifications from internet...

The small Bipolar (4-wires) one is STH-39H112
and a little biger Unipolar (5 wires) is STP-42D221-01

I have to check the Dir/Pin cables...Following is the some spad work i did on..Kindly help me recognising the common and Step/Dir pairs...

Am I right to say
5 wire motor:
-------------
Group A and B Common: 5
Group A phases : 1 2
Group B phases : 3 4

[wildwestpat]

From the resistance table you have compiled this is not a simple quadrature stepper motor. From the resistances you have measured wire 5 appears to be the common for a four phase drive with pins 1 through 4 going low in turn the shaft might rotate. However the drive circuit may have cycled the pins 1 through 4 both positive and negative with respect to pin 5. From the information you have gleaned from examining the motor you will be unable to ascertain the firing order other than by experimentation. Physical turning of the shaft with now power and all leads unconnected should reveal the magnetic dent or number of steps for a completed turn. The drive electronics used is likely to be a custom chip so that would not have helped decide on the drive sequence and service would probably be provided by board and or motor replacement if not regarded as making the entire machine scrap. The cost of spares and information provision makes printers and other gadgets that use therse small motors uneconomic to repair hence there is unlikely to be any information available as these tend to be oem special to application devices.

Hope this gets you turning - Pat

[george4657]

The 5 wire motor is a common 6 wire unipolar motor with the center taps joined together so only 5 wires come out of motor.
See this web page for an explanation of how to connect:
http://www.piclist.com/techref/io/stepper/wires.
The motor is small so will not have much power.

The bipolar motor can not be 3.7 degree/Step as this does not divide into 360
For example 360/1.8 = 200 steps , 360/3.7 = 92.3 steps??

George

[Khalid]

Thanks George and Pat...

This is a unipolar motor and the common is center tap inside the motor.. I will drive them with Arduino +Adafruit shield.. I hope i will get no trouble out of it..

As far as 4-phase motors concerned , can't it be controlled by Gecko etc.. I do know that the 5-phase motors require special controller / chip to drive in sequence...

[wildwestpat]

Try and complete the help page which George has pointed you at. This will help confirm that it is a stepper and the drive notation required. You won't need the Gecko current capability as this is a very small motor. Look towards using an IC direct drive.

George that Java sheet is brill - thanks.

Regards

Pat