Corona charge is deposited either as a 20ms pulse or while the brief push-button is pressed. The plate is then released by its push button, at the top right hand corner of the instrument, to swing away and uncover the sensing aperture of the JCI 140. Check in good lighting. Mount the JCI 140 Static Monitor into the JCI 149 and secure by finger tightening of the two mounting screws. With the two mounting screws fully retracted, the sensing aperture spigot of the JCI 140 is matched into the hole in the middle of the JCI 149 base unit and the body of the JCI 140 then moved towards the extrusion section until the pins on the two mounting screws can be screwed to engage with the socket heads of the two screws securing the backplate of the JCI 140.
Finger tighten the two mounting screws.
Rest JCI 149 assembly on a clean conducting surface and check that the reading of the JCI 140 is close to zero both with the swinging plate in the open and closed positions. Adjust zero setting if necessary. In general it is useful to leave the swinging plate in the closed position to protect the sensing aperture of JCI 140. This can be either a direct connection or a connection via a JCI 141 if the likely duration of the studies makes it sensible to use mains operation. This will give a more consistent pattern of charge with minimum risk of damage to the surface tested - or airflow disturbance by ionic wind when handling fine light powders.