Agilent Technologies 89410A Service Manual page 39

6
Check A102 Fan assembly.
a
Set the power switch to off ( O ) and disconnect the power cord
from the rear panel.
b
Remove the top cover.
c
Wait five minutes to allow time for the power supply capacitors to
discharge.
d Remove the power supply shield located on top of the analyzer
behind the display.
e
Disconnect the fan power cable from A95 P353 (red and black
cable).
f Connect 10 Vdc to the fan cable. The fan should be turning
slowly.
g
Increase the voltage to 24 Vdc. The fan should turn faster as the
voltage increases.
The power to the A102 Fan assembly is controlled by a thermistor
which varies the fan voltage between
cold and 28 V when the analyzer is hot. The thermistor is on the
+
A95 Main Power Supply assembly.
h
If the fan did not respond correctly, the Fan assembly is probably
faulty.
7 Check A95 Main Power Supply assembly voltages.
a Set the power switch to off ( O ) and disconnect the power cord
from the rear panel.
b
Place the analyzer on the side closest to the keypad.
c Remove the bottom cover.
d
Wait five minutes to allow time for the power supply capacitors to
discharge.
e Remove the black power supply shield.
f Connect the power cord and set the power switch to on ( l ).
g
Check the voltages in following table.
The ripple should be no more than 50 mVp-p. Do not include high
frequency line noise when measuring ripple. See
test locations.
Troubleshooting the Analyzer
To troubleshoot the power supply
8 V when the analyzer is
+
page 1-19 for
1-21