c. Install new lamp.
3-21. Low Pass Filter Bypassing. Under
certain conditions, the antenna cables
Reinstall indicator into control
are to be connected directly to the SAM
unit so that keyway tab is at
receiver. When the cables are connected
bottom and the word TOP is at top.
in this way, the low pass filter is com-
pletely bypassed. Your supervisor will
3-20. Removal and Replacement of
know when the filter is to be bypassed
Volume Control Knob. Remove and re-
and will tell you to make the connections
place the knob of the VOLUME control
that are needed. The procedure for
making the connections to bypass the
filter is as follows:
Rotate VOLUME control to full
counterclockwise position. This
puts the white dot on knob at
approximately 7 o'clock. It also
puts two knob setscrews at approx-
imately 10 o'clock and 1 o'clock.
Using 0.050-inch (across the flats)
hex key, loosen both setscrews
two or three turns and slip knob
off VOLUME CONTROL shaft.
With knob removed, make sure
Because specific locations of
that VOLUME control shaft is still
components vary from one air-
at its full counterclockwise posi-
craft to another, you may have
to look up the cables that con-
Slip replacement knob onto VOLUME
receiver in aircraft technical
control shaft. Keep approximately
manual to be sure you have
1/32-inch clearance (about thick-
ness of paper match) between back
of knob and edge-lit panel. Then
At SAM receiver, disconnect both
rotate knob counterclockwise to
rf cables that come from filter.
position white dot to approxi-
mately 7 o'clock.
At filter, disconnect two cables
Using 0.050-inch hex key, tighten
both setscrews with only enough
connect them to SAM receiver front
tension to make firm contact with
Check your work against connec-
Check for free rotation of knob and
tions shown here.
shaft in both directions.