IET Labs, Inc. 1864-1644, User And Service Manual, Page: 36 / 46

SERVICE AND MAINTENANCE
1864-1644 Positive Polarity Megohmmeter
26
Figure 6-2. Top interior view of 1864 Megohmmeter
Figure 6-3. Bottom interior view of 1864
Megohmmeter
* or any commercial equivalent
6.6 Knob Removal
If it should be necessary to remove the knob on a
front-panel control, either to replace one that has
been damaged or to replace the associated control,
proceed as follows:
1. 1. Grasp the knob fi rmly with the fi ngers,
close into the panel (or the indicator dial, if
applicable), and pull the knob straight away
from the panel.
CAUTION
Do not pull on the dial to remove a dial/knob as-
sembly. Always remove the knob
fi rst. To avoid
damage to the knob and other parts of the control,
do not pry the knob loose with a screwdriver or
similar
fl at tool, and do not attempt to twist the
Knob from the dial.
2. Observe the position of the setscrew in the
bushing, with respect to any panel
markings (or at the full ccw position of
a continuous control).
3. Release the setscrew and pull the bushing
off the shaft.
4. Remove and retain the black nylon thrust
washer,
NOTE
To separate the bushing from the knob, if for any
reason they should be combined off the instru-
ment, drive a machine tap a turn or two into the
bushing for a suf
fi cient grip for easy separation.