AC synchronous stepper motor question

[TF and the wire]

At the factory where I work, we have a machine with a pair of motors that traverse a couple of guides across a machine using push buttons. They are connected to a PCB containing 6 relays and 7 diodes. The external connections to this board are the push buttons, a 120v AC supply and the motors.

The PCB has failed and I am looking at replacing it with hard wired relays or contactors. It looks like all the board does is switch the 120v through to the motors to make them travel in either direction.

The motors are US made and have a label "AC synchronous stepper motor". I am trying to figure out how to connect to the motors. Each has 3 connections, and the drawing shows 2 windings in each motor, one end of each winding is connected to a common connection. the other ends are to their own terminal.

How is the 120v applied? How is the motor reversed? In GB a stepper motor would require a drive full of electronics, transistors etc and a synchronous motor would have different connections to what are on our motors. So I am thinking the terminology is different across the atlantic.

 

[Knobhead]

What do the machine makers have to say about it?

 

[TF and the wire]

The machine is nearly 20 years old and they say they don't support the parts fitted. However they can offer a modified system with new motors etc for silly money and they can do it in around 2 months time. Meanwhile my production manager wants it working next week, and the finance director says there is no money spare. Usual sort of reply.

 

[Knobhead]

Can the tracks on the PCB be traced out? I know it’s a ball ache but it’s the only way to make a drawing of what’s needed.

What do these motors look like? They wouldn’t have a liner actuator attached would they? There’s something lurking in the horrible dark recesses of my mind. A picture would help.

 

[Knobhead]

If it's the kind of motor I'm thinking of this may help

View attachment 11973

 

[TF and the wire]

There is no capacitor that I can see. When I first saw the internal diagram of the motor I immediately thought that one winding was forward rotation, the other reverse. It's the label stating that it is a stepper motor that is throwing me. Surely if it was a stepper motor it would have a more complicated drive unit.

I intend tracing out the PCB when get a chance, it just needs someone to sit down for an hour or so to do this. Easier said than done in a busy factory.