Emco 5PC steppers

[ptjw7uk]

Only thing I can say then is that the only driver I have that exhibits those symptoms is kaputt!!
I even tried other motors on the driver - same result!
Peter

[Ian Hart]

Thanks anyway.

Ian

[irving2008]

some steppers are reverse wound... mine are wired A+ = Orange + Yellow/white A- = Yellow + Orange/White etc... try swapping them... or it could be that you need to pair them differently e.g. not Red + Brown, but Red + Yellow or Red + Orange (and then it might be Red + Y/W or Red + O/W!) Basically try all combinations till you find the right one...

[John S]

Don't try swapping wires and connecting to the driver, you can blow drivers that way.

Basically you have 4 coils, 8 ends so you can measure continuity between two wires and that's one coil.

The stepper may be kaput if when all the leads are twisted together you can still turn the motor easily. I bought one off ebay that did this, sent it back.

.

[ptjw7uk]

Ian,
Are you wiring in series or parallel, try as John said first, then ...
I remember reading on the web that you could find out how the coils were wound using a meter although not sure how you find out to what pair they belong!
Last resort is try to find a data sheet.

Peter

[Ian Hart]

Thanks all

I'm at a show over the weekend so it'll be next week before I try. Ill post progress.

Thanks again

Ian

[irving2008]

The point is you have 4 windings A1 A2 B1 B2. You need to parallel A1 and A2 in the same magnetic phase and B1 & B2 ditto. While continuity testing with a meter can validate that say, Orange + Orange/White is a winding it wont tell you whether it is A1 A2 B1 or B2 or whether A1 is reverse wired to A2. The only sure way to do that is consult the datasheet or observe the voltage generated in the windings with a 'scope while rotating the motor by hand. It is possible to work it out another way with the aid of a power supply of around 5v and 1A capability. This assumes the stepper has a winding resistance of 2.5ohm or more per individual coil.

1. Pick a winding.. lets say Brown. call it A1-1 (Brown) and A1-2 (Brown/White).
2. Pick another one lets say Orange. wire it Brown to supply +, brown/white to Orange, orange/white to supply minus. This puts two winding in series. Turn on the power, make sure the current is OK (~1A). Is the rotor locked? If it isnt then this second winding is A2 and is reverse wound to A1 (i.e Orange is A2-2, Ornage/White is A2-1). verify this by reversing A2 and checking the rotor locks. Repeat with remaining 2 coils to verify same behaviour (B1, B2)
3. If the rotor was locked in step 2 then the Orange winding is either a normally wound A2 or is B1 or B2. In this case first reverse the Orange winding. If its now not locked then Orange is A2-1 and Orange/White is A2-1. Repeat test for the remaining 2 windings to determine orientation of B1 and B2. If it remains locked in both cases, pick another winding and try again. Repeat until you find two windings that lock in one direction but don't lock when one is reversed.

The diagrams might help explain this...

[Ian Hart]

Thanks

I'll get to that next week. I have a CNC mill, so I intend to connect a driver to a known working stepper, on the mill, first to confirm that this is a wiring issue.

Ian