TM-9-1200-215-34-P
AUTOMATIC FIRE CONTROL SYSTEM (AFCS)
TECHNICAL MANUAL; DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE MANUAL
FEBRUARY 1999
TM-9-1200-215-34-P - Page 142 of 266
TM 9–1200–215–34&P
5–4
(2)
The VMS Modem Heatsink Assembly circuit card supplies conditioned +5 Vdc to the VMS Modem and
the VMS from the unconditioned +24 Vdc vehicle power.
The Heatsink Assembly also contains the phase locked
loop circuitry used to detect the individual frequencies of the signal transmitted across the slip rings.
(3)
The Cable Assembly connects the circuit card assembly receptacles to the J1 and J2 receptacles.
They
transmit and receive data for BIT, odometer, loopback, power, voltage, test commands, and ground, via the
internal wiring.
(4)
LRU interface.
The J1 connector provides the operational interface with the VMS Modem CCA and the
VMS Modem cable.
The pin assignments, given in figure 5–2, reflect the schematic nomenclature.
(5)
Test interface.
The J2 connector provides the VMS Modem CCA test interface.
The pin assignments,
given in figure 5–2, reflect the schematic nomenclature.
5–10.
MANUAL TROUBLESHOOTING PROCEDURE
DESCRIPTION
This task covers:
Manual Troubleshooting
INITIAL SETUP
Tools:
Tool Kit, JTK–17LAL, TK–101/G, and TK–105/G
(items 37, 38, & 39, Appendix E)
Pin Adapters, Test #16, #20, and #22 (items 4, 5, &
6, Appendix E)
Socket Adapters, Test #16, #20, and #22 (items 7, 8,
& 9, Appendix E)
Electrical Lead (item 14, Appendix E)
Equipment Condition:
Unenergized VMS Modem is on workbench
Personnel Required:
One MOS 35Y
NOTE
•
The following manual troubleshooting procedures consists of wiring diagrams locating box
edge connector pins to internal harness connector terminations.
Continuity checks using this
chart are intended to be used when replacement of internal components (i.e. CCAs) fail to
correct an Electronic Shop, Transportable, AN/TSM–191(V)3 indicated fault.
All other
internal troubleshooting will be performed by automated testing.
Refer to TPS 12958912 for
specific CP troubleshooting procedures.
•
The continuity check is performed to test for the existence of a connection between two
contacts on the cable.
The two probes from an ohmmeter are touched to the appropriate pair
of contacts and the ohmmeter is monitored.
Low resistance readings (approaching 0 ohms)
show a good connection, high resistance readings (approaching infinity) show a degraded or
broken connection.
Figure 5–2 shows what contacts the probes should be placed on to
check for continuity on the VMS Modem cable assembly.
MANUAL TROUBLESHOOTING
1.
Check for continuity using figure 5–2.
Change 1
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