by defective current transformers. Both 60 Hz and 1400 Hz
b. Disassembly. After inspection and testing,
ammeters read full scale for 100 ma. Check alumel-chromel
disassemble the wire harness only as required for repair or
leads, resistor, and exhaust gas thermocouple at the engine
replacement.
before replacement of the exhaust gas temperature indicator.
c. Cleaning and Inspection.
(4) Test switches and relays by. continuity check.
(1) Clean wire harness with a clean, lint-free cloth
Refer to the power plant schematic and wiring diagram in TM
moistened with an approved solvent and dry thoroughly.
5-6155-586-12 for switch and relay contact arrangement.
(2) Inspect for damaged or loose connector pins
(5) Replace all parts that are damaged beyond
and damaged wires. Check for any evidence of burned areas
simple repair and all parts that are proven defective by
indicating shorts. Inspect connectors for damaged or stripped
testing.
threads.
c. Reassembly and Installation. Refer to TM 56115-
d. Testing. Refer to the wire run chart in figure 525 and
586-12 for reassembly and installation instructions.
check individual wires for continuity.
5-27. Conditioned Air System
Electrical Components
e. Repair, Replacement and Reassembly.
Panel
a. Removal and Disassembly. Refer to TM 56115-586-
(1) Solder connections will be made in
12 for removal and disassembly instructions.
accordance with MIL-S-6872 using solder Type SN60WRP2
per Fed Spec QQ-S-571.
b. Cleaning and Inspection. Refer to TM 56115-586-12
and perform cleaning and inspection procedures as
(2) Replace defective wires with wire in
instructed.
accordance with MIL-W-5086, Type II.
Wire size and
approximate length in inches is provided in figure 5-25.
c. Testing.
(3) If self-clinching cable straps are removed to
(1)
Test time delay (K17, K18) as follows:
facilitate repairs, install new cable straps at two inch intervals
and at all cable breakouts.
(a) Connect the negative side of a 24 VDC
source to pin E of the relay connector.
f. Installation. Install the wire harness assembly in
reverse order of removal procedure.
After installing
(b) Connect +24 VDC to pin C; then check
connectors, safety wire in accordance with MS35540 using
for closed circuit between pin D and pin H, and an open circuit
lockwire MS20995C20.
between pin D and pin G.
5-26. Instrument Panel Assembly
(c) Connect +24 VDC to pin A (-24 VDC
lead remains at pin E); then check that circuit opens between
a. Removal, Disassembly, Cleaning and Inspection.
pin D and pin H, and closes between pin I) and pin G.
Refer to TM 5-6115-586-12 for these instructions.
(d) Check the time delay by connecting
b. Repair, Testing, and Adjustments.
ohmmeter across pin A and pin F. The ohmmeter should
(1) Test and repair the panel wire harness
indicate an open circuit. Connect -24 VDC lead to pin B and
assembly as follows.
+24 VDC lead to pin D and check the ohmmeter indicates
closing of pin A to pin F circuit within 30 3 seconds for K17
(a) Refer to the wire run chart in figure FO-
and within 60 6 seconds for K18.
1 (located in back of manual) and check individual wires for
continuity.
(e) If the relay does not operate properly in
any of the above tests, it is defective and must be replaced.
(b) Replace defective wires with wire in
accordance with MIL-W-5086, Type II.
Wire size and
(2) Test relays K23, K24, K25 and K26 by
approximate length in inches is provided in figure FO-1.
applying a source of 24 VDC across the coil (observe polarity:
positive to terminal X 1; negative to terminal X2) and checking
(c) Solder connections in accordance with
that the three sets of N.O. contacts (L1-T1, L2-T2, and L3-
MIL-S-6872 using solder Type SN60WRP2 per Fed Spec QQ-
T3) close with power applied and that there are no short
S-571.
circuits between them. Check that circuits open when 24 VDC
(d) If self-clinching cable straps are
source is disconnected.
removed to facilitate repairs, install new straps at two inch
(3) Test relays K19, K20, K27 with 24 VDC
intervals and all cable breakouts.
source across the coil (observe polarity, positive to terminal
(2) Meters may be electrically tested by
X1; negative to NEG). Contact arrangement is A1-A2 N.O.,
comparison with calibrated standard meters. Adjust meters
B1-B2 N.O., CI-C2 N.O., 11-12 N.O. and 12-13 N.C.
by turning adjustment screw, located in face of meter, until
meters read the same as the calibrated standard meters. If
synchronization of meters is unobtainable, replace inoperative
meter.
(3) Test ammeters before replacement
as
incorrect readings during operation may be caused
5-36
