TM 5-6350-280-23&P
Table 4-2. Troubleshooting Table - continued.
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
3. TWO MODULE (MOD) FAILURES ON SAME BACKPLANE - continued.
NOTE
Refer to figure 4-4, Appendix E and tables 4-6 through 4-10 for schematics and
wiring diagrams.
Step 5.
Set oscilloscope to settings specified in figure 4-3, connect A probe ground to ground pin on CPU CCA
and connect A probe to RXD pin on either CPU CCA. Refer to figure 4-3 and check for RX signal input,
upper waveform figure 4-3.
If RX input signal is present go to step 8, otherwise go to step 6.
NOTE
Oscilloscope settings do not change.
Step 6.
Position A probe ground on terminal 4 and A probe on terminal 5 of connector P2, left backplane, or
connector P3, right backplane. Refer to figure 4-3 and check for RX signal input, upper waveform
figure 4-3.
If RX input signal is present go to step 7, otherwise refer to paragraph 4.6.5 and replace RX-TX cable
assembly.
NOTE
·
Do not remove CPU CCA(s) while equipment power is on.
·
Oscilloscope settings do not change.
Step 7.
Refer to TM 5-6350-280-10 turn equipment off, refer to paragraph 4.6.8 remove CPU CCAs, refer to
TM 5-6350-280-10 turn equipment on. Position A probe ground on terminal 26, RX signal return, connect
A probe to terminal 27 of CPU CCA connector on backplane. Refer to figure 4-3 and check for RX input
signal, upper waveform of figure 4-3.
If RX input signal is present refer to paragraph 4.6.8 and replace CPU CCAs, otherwise refer to
paragraph 4.6.9 and replace backplane.
NOTE
Oscilloscope settings do not change.
Step 8.
Connect B probe to TXD pin on either CPU CCA. Refer to figure 4-3 and check for TX output signal,
lower waveform figure 4-3.
If TX output signal is present go to step 9, otherwise refer to paragraph 4.6.8 and replace CPU CCA.
4-9
