(1) To trace a circuit on a board assembly, as
(c) Coat the threads of the screws (121) with glyptal.
instructed in a signal substitution test procedure
(d) Check the end play of the sprocket, gear, and flange
connector on the interconnecting board from which the
assembly (119). Add shims as necessary to limit the
board assembly was withdrawn. The symbol 1A will be
end play between 0.001 and 0.003 inch.
found inscribed on the interconnecting board to the
upper left of the connector. This indicates that the prefix
(e) Install the belt (116) and secure with the retaining
1 must be assigned to all the letters in the top row of the
connector and the prefix 2 to all the letters in the bottom
row. The letters are stamped into the face of the
(f) Secure the block (34) to the housing (198) with the
connector at both rows, beginning with an upper case A
two screws (35). Secure the shield (32) to the block (34)
at the left and the lower case letters on the right.
with the two screws (33). Coat the threads of the screws
However, it must be noted that all letters of the alphabet
(33) and (35) with glyptal.
are not included.
(2) Further identification of interconnecting
e. Removal of Sprocket Wheel, Gear, and Pinion Shaft
board assembly connector contacts can be made in
figures 6-8 and 6-29.
Use these illustrations in
conjunction with an assembly schematic, as it
designates each connector contact by number or letter
(a) Remove the two screws (101, fig. 34 (4)) and two
and shows those that are tied together and those which
screws (103) securing the support pad (100) to the
(3) To locate a specific "pin" on a board assembly, first
(b) Remove the retaining ring (124, fig. 3-4 (5)) the shim
locate the pin letter on the interconnecting board
connector and starting from either side of the connector
(c) Support the sprocket and flange assembly (122) and
count the number of contacts to its location. Orient the
carefully tap out the pin (123).
board assembly to the position into which it is inserted
(d) Withdraw the shaft (127) with the pinion gear (128)
into the interconnecting board connector and count off
the same number of contacts, as was done to locate the
"pin" on the interconnecting board.
(a) The replacement of the sprocket wheel, gear, and
pinion shaft is a reversal of the removal procedures of
the components and connections of the various board
(1) above and the special instructions described below.
assemblies and indicate the positions of the parts by
(b) Use the shim (125) to obtain an end play of 0.0002
Assemblies, parts, and
to 0.0022 inch under 3.50 + 0.25 pounds reversal axial
connections can thus be identified on a board assembly
by reference to its wiring diagram.
4-38. Repair and Alinement of Control, Aircraft
4-39. Disassembly and Reassembly of an AEC
Camera LA-412A Components
Board Assembly a. Disassembly.
a. General. Procedures for the repair and alinement of
camera control assemblies and parts by general support
installation of an aec board assembly.
(2) Before starting the removal of a part or assembly,
47. The removal and replacement of assemblies and
refer to figures 622 and 6-23 to identify or confirm by
parts from a board assembly involves the removal of an
reference designation the location of each unit.
electrical insulating compound that is used to coat the
identifying the "pin" contacts of the board assembly and
concerning the compound and also for additional
to trace circuits.
instructions that pertain to repair and alinement
(4) Exercise great care in the removal of the electrical
Tracing Circuits on Board Assemblies.
insulating compound (para 3-7) that coats the wiring and
components of the board.
connector contacts on each board assembly have no
"pin" markings but they can be easily identified, as