2. Service
Assembly/Module Diagnostic Trees (Diagnostic Section 3)
98
3.3.4. A8 Front/Rear-Panel Sync Input Test
1 Connect the pulse generator output to the front panel Sync input.
2 Set the pulse generator to apply 0 to 3.0 volt pulses of 1 microsecond length
at a rate of 10 pps.
3 Use the CLOCK/Sync menu to arm the front input.
4 Observe the LCD display and record the displayed message.
5 Repeat steps 1 through 4 using the rear-panel Sync input.
QUESTION: What message was displayed on the LCD?
If the LCD display shows: Caught
a sync pulse for both
Sync inputs, A8 is operational,
continue testing
If the LCD display shows: Sync
timed out for one or both Sync
inputs, Go to, 3.3.4.1.
3.3.4.1 A8 Sync Fault
1 Remove instrument power and replace A8.
2 Repeat procedure 3.3.4.
QUESTION: Does the LCD display Caught a sync pulse
for both inputs?
If Yes: Retain new A8 and retest.
If No: Go to, 3.3.5.
3.3.5. A8-to-Chassis Interconnect Test
1 Remove instrument power.
2 Remove A8 from slot XA8.
3 Carefully remove the five SMB cable connectors (Note their locations first.)
from J14, J15, J16, J17, and J18 on A1.
4 Verify continuity and rule-out short-to-ground for all five cables and their
corresponding front- and rear-panel 1 pps output and Sync input connectors.
Record results.
5 Reconnect the verified cables and BNC connectors.
QUESTION: Are any of the five SMB-to-BNC cable assemblies
open or shorted?
If Yes: Replace the cable assembly as required, reinstall A8 and retest.
If No: A1 may be defective, contact Symmetricom for further assistance.