Balance Procedure

To balance the instrument it is convenient to use the rotation secondary limit bypass system.  In short, with the instrument rotated such that it is not near a secondary limit (i.e., the puck near the middle of travel), one needs to open the circuit breaker cabinet and flip the Normal/Bypass switch into the Bypass position. Note, this will disconnect the Galil servo drive system so when you are done it must be put back into the Normal position.  Now, you will need a helper to push the red bypass pushbuttons while you monitor the ammeter on the circuit breaker panel. When the pushbuttons are pushed the ammeter gives you a reading of the current flowing to the rotation motor.  When the instrument is in balance, the current reading will be within about 0.1 - 0.2 amperes when rotating in either direction.

Loosen cylindrical cover (D8801) over counterweight assembly (D4096). This cover must be in place while measuring balance and must be lifted up or removed to change weights.

Rotate DEIMOS to mechanical position angle 180 per drawing D0002. Use procedure above to measure balance. Add or remove weights to balance instrument. Rotate to mechanical position angle 270. Balance by moving weights from one end of counterweight assembly to the other. Iterate as required.