Nasa mill with Fenner DC drives & SEM motors

[dresda]

Just picked a up Nasa knee mill with Fenner DC drives and SEM motors and Fagor 8025 control.
I finally got the control running, still putting in some parameters, got the Y & Z to move and home but nothing on the X axis. The motor is powered up and in torque but no movement when I try to jog, slight drift on the readout display but no movement on the following error and no alarms.
Anybody have any info on these drives.
Regards,

[dresda]

So I did a few more checks today. The motor is a SEM MT30 with Heidenhain ERO 120 encoder and built in tach. When I power up the X it just sits there in torque, when I grab the belt and pull the motor will pull back, but movement and no flickering on the following error.
I switched the drives, same thing. I reversed the tach wires the motor ran away but did register a value on the X position display when it ran away which leads me to believe the encoder is ok?
I can’t see the tach because it’s inside the motor behind the encoder and I don’t see any brushes, I was hoping I could clean the com and brushes.
Can I put a 12 v battery charger to the motor and check the tach, or more to the point, how can I check the tach, it looks too difficult to remove the encoder and knowing my look, the tach will be good but I will break the encoder getting it off the motor.
Regards.

[Al_The_Man]

If it is a DC tach you should see a DC output the level of which will be proportional to RPM and polarity depending on direction.
Spin the motor by feeding it with an external supply such as a automotive battery.
Al.

[mike_Kilroy]

=dresda;860772]So I did a few more checks today. The motor is a SEM MT30 with Heidenhain ERO 120 encoder and built in tach. When I power up the X it just sits there in torque, when I grab the belt and pull the motor will pull back, but movement and no flickering on the following error.

seems if you MOVE the motor some by hand and you don't see f-error yoru encoder is not working or wires back to control bad...... but motor/tach will try to hold position even without control or encoder but you should see FE if you move motor by hand. why not try turning off power or command to drive so it does not fight you and move motor by hand and watch display - does the encoder work or not. black and white.

I switched the drives, same thing. I reversed the tach wires the motor ran away but did register a value on the X position display when it ran away which leads me to believe the encoder is ok?

Hmmmm. see above.... and reverse tach and it runs away; sure tells me the tach is FINE - dont mess with it! your symptoms do NOT match a bad tach symptom at all. What does 'register a value on x display' mean? how much? Your symptoms are really saying you have no command to drive to move when you say move.

I can’t see the tach because it’s inside the motor behind the encoder and I don’t see any brushes, I was hoping I could clean the com and brushes. Can I put a 12 v battery charger to the motor and check the tach, or more to the point, how can I check the tach, it looks too difficult to remove the encoder and knowing my look, the tach will be good but I will break the encoder getting it off the motor.

I would not touch the tach. If encoder or its wiring was bad, then when control told it to move, it would run away. it does not run away it just doesnt move. so u r not even getting command from control to drive in my opinion. check there instead. tell it to jog while watching the +/-10vdc speed command to the drive at its terminal strip with a voltmeter - if there, the drive is bad, if not there as I suspect, the control analog output is bad.

[dresda]

I think there is a problem in the control (fagor 8025) I did change the master board from a lathe and switched some of the chips over, maybe I bent a leg on one of the chips, just got to find out which chip controls the axis.
Thanks for the reply.
ray.