Fadal 904-1 does not respond to inputs

[tigerinnovation]

Have 1988 model Fadal 904-1 with 88 control.
Initially had problem with an occasional runnaway. Then machine quit operating. All boards from this machine have been put in a similar machine and the other machine operates fine with all these boards installed. (This included memory expansion, cpu, video, bus interface, x, y and z axis, spindle controller, clock card, mill interface). The amp cards were checked but were not put in the #2 machine.
Screen says amplifier fault. When handwheel is rotated the readout shows movement, but no movement occurs.
Will not cold start, jog in any axis and creeps slowly.
Any ideas?

[Al_The_Man]

Sounds like it could be amplifier/drive or drive power supply problem, that age of machine, most likely DC servo's.
Check the analogue intput to the drive when you crank the handwheel, if the axis is not turning the analogue signal should go up to +or- 10vdc, if it does and the axis does not move then it is either the drive or P.S..
If you do not get an analogue command, then it is in the controller.
Also make sure the drive enable is at the correct logic level, (i.e. ON).
The display generally displays the anticipated position, not the actual.
Al.