TM 55-4920-399-13&P
CHAPTER 4
AVIATION INTERMEDIATE MAINTENANCE INSTRUCTIONS
Section I. PREPARATION FOR MAINTENANCE,
STORAGE, AND RESHIPMENT
4-1. Preparation For Maintenance. Preparation
a. If the original shipping container is available,
for maintenance proceed as follows:
repack the Test Set as originally received, using
the styrofoam corners in eight places to cushion
a. Carefully remove the lid from the shipping
the Test Set in the wooden container.
container and remove the packing material.
b. If the original container is not available, ob-
b. Remove the Test Set from the shipping con-
tain or make a wooden container with sufficient
tainer.
room for supportive packing materials inside the
container. Allow space on the bottom, around the
4-2. Preparation For Storage. Preparation for
sides, and on the top so that the Test Set will be
storage proceed as follows:
held securely in place during shipment.
a. All knobs and controls shall be set to zero,
Insert an adequate amount of prepackaged
C.
neutral, null, or off position and all cables, cable
dissicant material (item 1, Table 1-4) in the ship-
adaptors, shorting plugs, and switchbox shall be
ping container.
secured in the carrying case.
d. Secure the container lid in place. Mark the
b. Clean any visible dust and dirt from the Test
container FRAGILE.
Set.
e. If the Test Set is being returned to the factory,
c. Close the lid and secure the four clamps and
affix a label containing the following information.
close the air valve on the cover.
Test Set Part Number
4-3. Preparation For Reshipment. Follow instruc-
Serial Number
tions for PREPARATION FOR STORAGE except
Contract Number
partially open the air valve.
Name of Contractor
National Stock Number
Section II. CHECKOUT AND ANALYSIS
4-4. Checkout And Trouble Analysis. The follow-
counter and should produce a binary counting se-
ing procedures are necessary to verify proper
quency from 0000 to 1001 (0-9).
operation of the designated circuit cards.
a. Three other sets of pins (24-27, 20-23, 16-19)
should also produce a binary counting sequence
necessary to check the waveforms in the following
from 0000 to 1001 (0-9). Each set of four pins is a
checkouts.
higher frequency and represents less significant
b. The checkouts consist of verifying that the
digits.
outputs at the pins on each board are within
b. Pins 5, 7 and 10 are outputs of the three-phase
specification, If not within specification, replace
clock and should show the following waveforms
board. Refer to Figure 4-1 for circuit card location.
(refer to fig. 4-2).
c. Pins 8, 6, 9 should produce the complement
4-5. Digital Board A1. (Refer to FO-1 and FO-2.)
(refer to fig. 4-3).
FO-1 shows the Al schematic used on serial
d. Pins 32 and 33 should produce complemen-
numbers 104, 106, 107, 109, 111, 112, 113, 117, and
tary square waves of approximately 5 Khz, related
123. FO-2 shows the Al schematic used on all other
to LO Z voltage (refer to fig. 4-4).
units. Pins 1, 2, 3 and 4 are outputs of the MSD
4-1
