TM 9-4935-294-15/2
Caution. Exercise extreme care when removing
in paragraph 4-17 e.
BWO tube to avoid damage to adjacent and related
f. Disassembly and Assembly of the Counter
electronic, electrical and mechanical components
Assembly.
and assemblies.
(1) Disassembly. To disassemble the counter
(1) Remove left side cover (1, fig. 4-31) by
assembly,
follow the order of removal shown in
removing 10 screws (2) attaching it to rf head chassis
exploded view, figure 4-30, and refer to wiring diagram,
(41).
Caution. The soldering iron used should be pencil
(2) Assembly.
To assemble the counter
type, 15 watts or less, connected through a
assembly, refer to exploded view, figure 430, and wiring
thermostatically controlled stand. Apply soldering
diagram,
and reverse the order of
iron so it touches solder point only.
disassembly. Observe the following procedures:
(2) Unsolder and remove the green, orange,
(a) Cement counter window (23, figure 4-30)
and blue harness leads from connector bracket
to counter assembly (19) with type III, MIL-E-5092A
assembly (3) solder lug (. over to 17, fig. 4-12).
adhesive.
(3) Free connector bracket assembly (3, fig.
(b) Obtain gears (16) and (17). If they are
replacements, ascertain that they are the proper parts
(4) Place connector bracket assembly on the
and have been inspected.
adjacent work surface so that back of connector and
(c) Turn variable resistor R1502 (18) fully
back of dispersion PC board assembly (refer to 1, fig.
ccw.
(d) Set dials of counter assembly (19) to low
further disassembly.
end of frequency band.
(5) Unsolder and remove red harness lead
(e) Install gear (17) on counter assembly (19)
from terminal 2 on dispersion PC board assembly (refer
shaft and engage with gear (16). Do not tighten
to 1, fig. 4-12).
setscrew.
(6) Remove male connector contacts 7, 16,
(f) Install gear (16) on shaft of variable
and 19 (refer to 13, fig. P12) from connector (10, fig.
resistor (18). Do not tighten setscrew.
P12).
Follow applicable procedures outlined in
(g) Check counter setting and position of
paragraph 417 e (1).
variable resistor (18). Both settings must be as specified
(7) Remove the following attaching hardware
in (c) and (d) above.
from waveguide support (39, fig. 431) and directional
(h) Secure gears to respective shafts
coupler (18) flange engagement in indicated order:
with setscrews.
(a) Four hex nuts (6).
4-23. Disassembly and Assembly of A-Band Rf Head
(b) Four washers (7).
To disassemble the A-band rf head, refer to exploded
(c) Two screws (8) from waveguide support
view, figure 4-31, and wiring diagram, figure 4-32, and
side.
follow procedures a through d below.
(d) Two screws (9) from flange engagement.
Note. Systems with serial nos. 127 and up use PC
(8) Remove four screws (4) from tube support
board assembly 7923063-1 for item 23 and systems with
brackets.
serial nos. 101-126 use 7923067-8.
(9) Slide BWO tube (5) and waveguide
a. Removal of BWO Tube 7923S11. Before removing
assembly (11) from rf head chassis (41).
BWO tube, read and observe all instructions appearing
(10) Disassemble waveguide assembly
on the tube and rf head case. Since BWO tube
(11) and BWO tube (5) by removing four hex
emanates strong magnetic fields, all work must be
nuts (6), four washers (7), and screws (9).
performed in a location free from possible magnetic
b. Replacement of BWO Tube 7923113.
fields. Work surfaces and tools must be non-magnetic.
(1) Obtain a replacement BNWO tube; unpack and
Refer to exploded view, figure 4-31, and wiring diagram,
inspect for possible shipping and/or handling damage. If
Remove BWO tube as follows:
BWO tube is in satisfactory condition, proceed with the
installation.
4-49
