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Step 8. Using a DMM and/or an oscilloscope, measure the +5 volt
power supply at connector J13 on the Motherboard. Refer
to Figure 5-1 and Table 5-1, (page 505).
Step 9.
Press the 373XXA Power key off, and and reinstall the A13
and A14 PCB’s removed in Step 6.
If any of the DC voltage tests fail in steps 1 through 8 above, replace
the power supply module.
If any of the DC voltage tests fail with the power supply module con
-
nected to the 373XXA Motherboard — but pass with it disconnected —
then the most probable cause of the failure is that one of the 373XXA
assemblies is demanding an excessive amount of current. To locate the
failed assembly:
1.
Press the 373XXA Power key off, and unplug a single assembly.
2.
Press the 373XXA Power key on, and note if the failed power sup-
ply functions normally.
3. Repeat Steps 1 and 2 until an assembly is found that clears the
power supply failure. The removed assembly is suspect and
should be replaced.
5-5 SYSTEM DOES NOT
BOOT-UP
If the 373XXA does not boot-up when it is powered-up, perform the
checks described below.
Boot-up Process
Sequence
The boot-up process is controlled by the firmware located on the A9
PCB assembly (processor PROM) The boot-up activities include:
q
Testing and initializing the A9 Main Processor PCB
q
Testing communication between the A9 PCB and the digital PCB
assemblies (A13, A14, A15, A16). The following messages will be
displayed at this juncture:
n
Initializing front panel knob (A14/A20)....
n
Initializing GPIB (A13/A18)....
n
Initializing external keyboard (A13)....
n
Initializing external trigger (A13/A5)....
n
Initializing front panel (A14/A20)....
q
Loading of system software from disk into memory
q
Starting operation of the system software.
q
System is booting—message is displayed.
TROUBLESHOOTING SYSTEM DOES NOT BOOT-UP
373XXA MM 5-7