Agilent Technologies 89410A Service Manual page 38

Troubleshooting the Analyzer
To troubleshoot the power supply
4
Check the A95 Main Power Supply assembly's bias supply voltages.
a
Check the bias supply voltages in the following table.
The ripple should be no more than 50 mVp-p. Do not include high
frequency line noise when measuring ripple.
Test
Location
U341, pin 3
U340, pin 2
U350, pin 3
b
If any of the voltages are incorrect, the A95 Main Power Supply is
probably faulty.
The A95 Main Power Supply assembly has no adjustments.
Therefore if a voltage is incorrect, replace the assembly.
c If the voltages are correct and the fan is turning, go to Step 7.
5
Check the supply voltage fuse for the A102 Fan assembly.
a
Set the power switch to off ( O ).
b Wait five minutes to allow time for the power supply capacitors to
discharge.
c
Measure the resistance across A95 F353.
d
If the resistance is greater than 0
1-20
Nominal Minimum
Voltage Voltage
+5 V +4.5 V
+12 V +11.4 V
−12 V −12.6 V
Ω
, replace the fuse.
Maximum Ripple
Voltage Tolerance
+5.5 V 50 mVp-p
+12.6 V 50 mVp-p
−11.4 V
50 mVp-p