Originally Posted by drsparky
DC servo needs a feedback signal and normal use a square wave for control of position. You may need to view the output on a scope meter or an oscilloscope. A normal millimeter will not give you a true picture of the output.
Doc, I think he has a 90 volt permanent magnet DC motor, not a servo motor. He did not mention any feedback.
OP. The small power supply you speak of is most likely a mini DC drive. Does it have a pot on it to adjust the speed? Heres how to set it up correctly.
Put your meter leads on the connections at the motor or control. (you have only 2 wires, right?) A1 & A2?
Turn speed pot fully clockwise (full speed) and check voltage. It should be at 90 VDC. If not adjust pot (Max) until you achieve 90 VDC.
Now turn the speed pot all the way CCW until the motor stops. Now turn the (Min) pot CW just until it tries to turn. Back off just a tiny bit and your set.
10% over speed is fine. The true way to test speed is with voltage. If the motor does a good job at 90 volts leave it at 90. If you need a little more speed just adjust the (max) pot, not to exceed 10% of full voltage.