
8712ET/ES and 8714ET/ES Troubleshooting and Block Diagrams
RF Network Analyzers Category 1 Failures: Dead or No Display
Service Guide 4-9
2. If the voltages are correct, but there is a probe power problem
Remove the front panel and check the fuses on the back of the front-panel PC board.
Continue with the section “Troubleshooting Digital Group Problems”.
Removing the Assemblies
If your problem has not been solved at this point in the troubleshooting process, it is highly
probable that one of the assemblies is causing the power supply to shut down. This may be
caused by the other boards having bad contact with the backplane. Give each board a push
to make sure it is firmly seated. If the problem persists, remove the assemblies one at a
time, and note which one is causing the shutdown. Refer to Chapter 3, “Assembly
Replacement” for disassembly instructions.
NOTE It is possible for the flexible metal “fingers” or a backplane connector pin to
break off and cause a short, so check for loose pieces of metal.
Verify that none of the pins on the back-panel connector are bent. This is a
common cause of shorted supplies or other nonfunctional problems.
Suggested order for assembly removal (easiest to most difficult):
1. front panel assembly (A1)
2. display assembly (A7) (remove the ribbon cable while it is outside the analyzer;
reinstall and see if the power supply is still shut down). If the A7 display assembly
appears to be causing shutdown, open the display enclosure cover (see Table 7-12, “A7
Display Assembly and Cable Locations,” on page 7-17) and make sure the board
assembly is firmly seated.
3. fractional-N/reference assembly (A3)
4. source assembly (A4)
5. receiver assembly (A5)
6. CPU (A2) and the disk drive assembly (A8)
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