Remove Assemblies; Roubleshooting Digital Group Problems; Error During Power-Up - Agilent Technologies 8711C Service Manual

Remove 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. his may be
caused by the other boards having bad contact with the backplane. Give each board a push to
make sure it is rmly seated. If the problem persists, remove the assemblies one at a time, and
note which one is causing the shutdown. Refer to the \Assembly Replacement" chapter of this
guide for disassembly instructions.
Note
It is possible for the exible metal \ ngers" or a backplane connector pin to
break o and cause a short, so check for loose pieces of metal.
Verify that none of the pins on the back-panel connector are bent. his is a
common cause of shorted supplies or other nonfunctional problems.
Suggested order for assembly removal (easiest to hardest):
1. A1 front panel assembly
2. A7 display assembly (remove the ribbon cable while it is outside the analyzer; reinstall and
see if the power supply is still shut down). If A7 display assembly appears to be causing
shutdown, open the display enclosure cover (see able 7-14 titled \A7 Display Assembly and
Cable Locations" in the \Parts List" chapter of this guide) and make sure the board assembly
is rmly seated.
3. A3 fractional-N/reference assembly
4. A4 source assembly
5. A5 receiver assembly
6. A2 CPU/A8 disk drive assembly
Troubleshooting Digital Group Problems
rror During Power-up
If there is no beep at power-up, but the CRT display is normal:
he problem is probably in the sound generator or speaker on the CPU board. Check the sound
generator ICs (U500-U503, U515-U517, and U300) and the speaker (LS501), or replace the CPU
board.
If there is no beep at power-up and no CRT display:
he problem is most likely one of two conditions:
No power to CPU board (no CPU LEDs on).
Another fault in the CPU assembly.
Look through the ES RESUL S hole on the rear panel to see if the LEDs are lit. If none
of the LEDs are lit, push the CPU board all the way into the backplane connector to ensure
a good connection. Note that it is also possible for the board to have a bad or intermittent
backplane connection and yet receive enough power to activate the LEDs.
If the LEDs are on, remove the CPU board (remove rear panel screws rst). hen reinstall
the CPU board, making sure to push it all the way in so that it connects properly with the
backplane. If there is still no beep at power-up and CPU error code LED continues to display
an \8," replace the entire CPU board.
T roubleshoot ng and Block D agrams 4-9