Agilent Technologies 4352B, Service Manual

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FIND OUT WHY THE F AN IS NOT ROT A TING
If the fan is not rotating, the problem may be in the A40 pre-regulator , the A50 DC-DC
Converter , the A2 post-regulator , or the fan.
1. Check the Line V oltage , Selector Switch Setting, and Fuse
Check the main power line cord, line fuse , and actual line voltage to see that they are all
correct. Figure 5-5 shows how to remove the line fuse , using a small at-bladed screwdriver to
pry o the fuse holder . F or more information about the line cord and line fuse , see the P ower
R equirements in Appendix B .
Figure 5-5. Removing Line Fuse
2. Check the A50 SHUTDO WN LED
When the fan stops , the A50 SHUTDOWN LED is o. See the Figure 5-11 P ower Supply Block
Diagram 1. The fan generates a F AN LOCK signal. The signal is fed into the F AN LOCK SENSE
circuit in the A50 DC-DC converter . If the F AN stops , the F AN LOCK signal is missing. Then
the F AN LOCK SENSE circuit activates the A50 shutdown circuitry , resulting the SHUTDOWN
LED turned o.
P erform the following procedure to check the A50 SHUTDOWN LED on.
a. Remove the analyzer's top cover and shield plate .
b. Make sure the A2 post-regulator is rmly seated and the cables are connected properly .
c. Turn the analyzer power on.
d. Look at the A50 SHUTDOWN LED . The LED location is shown in Figure 5-1.
If the SHUTDOWN LED is on, replace the A50 DC-DC Converter .
If the SHUTDOWN LED is o, check the cable connection between A50J2 and A2J4. If
the connection is good, continue with the TROUBLESHOO T THE F AN AND THE A50
DC-DC CONVERTER in this chapter .
P ower Supply T roubleshooting 5-7