trouble with the Mesa 7i76 connected to an AMC drive for the spindle

I am trying to operate a spindle with an AMC drive and the Mesa 7i76.
The AMC drive has an onboard +-10 voltage (@ 3ma) source for use as speed control.
Originally tried connecting for bi directional control - always went one direction and couldn't vary the speed.
Then tried for just single direction control and that didn't work.
Then connected the voltage source to the 7i76 and used a multimeter to read the output from the 7i76.
Couldn't get the voltage to change.
I then connected a wall wart (5 volt probably 500ma+) and I could change the voltage output from the 7i76.

So my immediate question is - is it possible that the current of the onboard voltage source is not enough?
Next question is that the AMC drive gives no maximuim current rating on the input of the velocity signal - could I use the 5 volt 500ma source directly?

Thank you.
Chris M

Yes 3 ma is not enough for the 7I76s analog output circuitry
I would use a 10VDC or 12VDC isolated supply (possible a wall wart)
The 7I76 needs about 8 mA so almost any supply will do, just make sure
its filtered DC and never greater than 15V