56 Chapter 1
Troubleshooting
Isolating an RF, Analog IF, Digital IF, Reference, Synthesizer, or CPU Problem
If the 30 MHz sample clock from the A12 analog IF assembly to the A10
digital IF assembly is not present, the display signal processor chip on
the digital IF assembly will not reset, causing the PCI bus to hang up
and the instrument will not boot.
To check the 30 MHz sample clock:
• Put the A10 digital IF assembly on an extender board
(E4406-60021).
• Check A10J4 for a 30 MHz signal using an oscilloscope, as shown in
Figure 1-11.
• If the signal is not present, the cause could be the A12 analog IF
assembly, or the A18 reference assembly. Go to "Verifying the A18
Reference Assembly" on page 50 to check the reference assembly.
If the boot-up process stops after the message Processor starting
auto-boot process appears, the firmware files on the A22A2 Flash
board may be defective. Try loading new firmware before replacing the
A22 processor or A22A2 Flash assemblies.
Look at the instrument screen and read any error messages that might
appear. The messages can give you a clue as to what is happening when
the instrument hangs up.
Battery
If you are experiencing problems with the real-time clock in your
instrument, it might be time to change the battery that is located on the
A22 processor assembly. The main purpose of the battery is to power
the real-time clock when no power is applied to the instrument. To
replace the battery, it is necessary to remove the A22 processor
assembly. Refer to Chapter 3 for removal procedures. The battery is
easily replaced by unclipping it from the board. Take care to install the
new battery correctly to ensure proper polarity.
WARNING Danger of explosion if battery is incorrectly replaced. Replace
only with the same or equivalent type recommended. Discard
used batteries according to manufacturer’s instructions.
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