2. Service
Top-Level Diagnostic Tree (Diagnostic Section 1)
37
Top-Level Diagnostic Tree
(Diagnostic Section 1)
This section describes the top-level diagnostic procedures for the 5071A
Primary Frequency Standard and provides pointers to lower-level procedures.
It is complete and must be performed sequentially. The procedures are
designed to troubleshoot an instrument that has failed in normal operation,
and is no longer able to lock-up correctly at power on.
When the complete procedure is performed on a functional 5071A, it will end
at section 1.0.8.2 with no errors or failures. The operational verification and
Performance Test procedures described in Chapter 1 of this manual must be
performed successfully on a repaired instrument before it is placed back in
service.
A transient error condition is evident when an instrument generates an error
or warning but subsequently passes the operational verification procedure
without any repair. This could for example occur when the cesium beam tube
(CBT) nears the end of its life.
In case of difficulty, contact Symmetricom for assistance.
1.0.0 First Power On
1 Remove the instrument from service.
2 Remove all external power.
3 Disconnect the internal-standby battery. (See Operating and Programming
manual, pg 2-15). (For Opt. 048, ensure that the rear-panel dc-line fuse
holder has a good fuse of the correct rating).
4 Ensure that rear-panel ac-line filter/cable assembly has a good fuse.
5 Remove 5071A top/bottom covers and top inner shield (see pg 4-3).
6 Power on the 5071A by applying dc or ac power.
7 Verify that all front-panel LEDs, the LCD, beeper, and keypad work:
a. Observe the large red seven-segment and small amber LEDs
momentarily illuminate.
b. Observe the LCD illuminate its top row of pixels followed by normal two-
row-display operation.
c. Check each key by pressing it and either hear or observe a confirming
response.
NOTE a & b above should occur within first few seconds of
operation.
QUESTION: Is the front-panel functional (beeper, LEDs, keyboard
operational)?
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