2. Service
Functional-Group-Diagnostic Trees (Diagnostic Section 2)
72
2.1.3.2.0 Rule Out Shorted Assemblies/Modules
1 Remove each printed circuit board assembly from A1 in a stepwise manner
and observe whether the resistance value for the faulty supply voltage returns
to normal.
2 Disconnect all module connectors to A1 in a stepwise manner and observe
whether the resistance value for the faulty supply voltage returns to normal.
3 Verify the Assembly/Module that causes the faulty supply voltage resistance
to return to normal.
QUESTION: Which assembly/module appears at fault?
If a specific assembly/module is isolated, replace, and retest.
If, after removing all loads from the motherboard, the resistance is still below
specification, replace A1, and retest.
2.1.4.0.0 Ext. DC Input Fuse Fault
The Ext. DC Input fuse blows when powering-on or running the
5071A. The assumption here is that ONLY the dc fuse blows, with the
instrument operating normally from the ac line or internal standby battery for
non-Opt. 048.
1 Remove all power and disconnect A11P101.
2 Replace the blown fuse.
3 Reapply dc instrument power.
4 Check the dc fuse immediately for possible open condition.
QUESTION: Did the fuse blow?
If Yes: The problem is either on A1 or in the wiring of the Ext. DC
connector which can be visually inspected for faults,
or in cable assembly 05071-60253
If No: Remove power, replace A11, and retest.
2.1.5.0.0 No Operation From Internal Standby Battery
(Note: Sections 2.1.5.0.0 through 2.1.5.2.0 do not apply for Opt. 048
instruments)
QUESTION: Does the 5071A operate at all from the
internal battery?
If Yes: Go to, 2.1.5.1.0.
If No: Go to, 2.1.5.2.0.
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