Gould Gettys Servo Amplifier Drifting User Guide

Hello Mates,
my milling machine is based on 3 N360 / A121 (I guess) servo amplifiers from gould. I believe they need a little adjustment to reduce drift (about 12 to 16V whe 0V at analog in). Thing is I can not find their manuals anywhere! Gould gettys has been dissolved, their tech support could no care less about my request. There is a guy selling one manual on ebay, but he will not ship to Brazil. Can anyone help? 



Greetings!

tommylight wrote:

Do NOT fix drift!
All analog servo systems will have a bit of drift at 0V input.
Wire the control, it takes care of it when encoders are in use.
 

Well, I wouldn't go that far.  Make sure the velocity DAC is outputting zero, and then adjust the "balance" or velocity offset put to get minimum drift.  You will not be able to get it down to absolute zero, but any drift in the amp will offset your position when not commanding movement.  If you really have 12 - 16 V output to the motor with zero in, then something is QUITE wrong!  That could be an open connection to the tachometers.  If the machine has been sitting a long time, the commutator of the tachs might be oxidized, maybe running the motors a bit might clean them.  Or, it could be a dirty connector contact.
Jon