Symmetricom 5071A, Assembly And Service Manual

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2. Service
Assembly/Module Diagnostic Trees (Diagnostic Section 3)
84
A2 Hot-Wire Ionizer Diagnostic Tree
This functional subsection describes the A2 hot-wire ionizer diagnostic tree
for the 5071A Primary Frequency Standard. Performance of these tests is
indicated by the presence of either a self-test or fatal error that reports a hot-
wire ionizer fault.
3.1.1.1.0 CBT Hot-Wire Resistance Test
1 Power off the 5071A.
2 Unplug cable from A2J1 and A2J2.
3 Using a 4-wire Ohm Meter, measure the resistance across pins
1 and 6 on the CBT cable.
QUESTION: Is the resistance between 0.1 and 0.25
Ω
?
If Yes: Go to, 3.1.1.1.1.
If No: Recheck results and Ohmmeter, then replace CBT.
3.1.1.1.1 CBT Hot-wire Resistance-to-Ground Test
1 Measure the resistance across pins 1 and 4 on the CBT cable.
QUESTION: Is the resistance greater than 200 k
Ω
?
If Yes: Go to, 3.1.1.1.2.
If No: Recheck results and DMM, then replace CBT.
3.1.1.1.2 Hot-Wire Monitor Test (No Current)
1 Remove instrument power.
2 Remove A2 CBT Controller.
3 Install the long extender board (05071-60052) into A2 slot.
4 Turn on the 5071A.
5 Use SCPI command
syst:print?
.
(Terminal-to-instrument via RS-232C data communication required.)
QUESTION: Is
HW Ionizer:
between -0.5 and +0.5 V?
If Yes: Go to, 3.1.1.1.3.
If No: Remove power, replace A7, and retest.