Emerson 404B Quick Start Manual page 18

Quick Start Guide
3. The gain control is a multi-turn "clutched" control. Turn it clockwise until
there is a clicking sound indicating that the control is all the way in. Then,
turn the control counterclockwise two full turns.
4. Replace the clear plastic cover.
If you still have erratic signals after making these adjustments, back out the
gain control another full turn or more until you obtain a satisfactory signal.
Note
Refer to the Balancing chapter of the AMS 2140 Machinery Health Analyzer
User Manual for more operating instructions for the 404B Infrared Phototach.
18
June 2018
MHM-97921, Rev 0