HP 9845B/C CE Handbook page 58

5·2
9845B/C Diagnostics
If the quick checks have failed, an assembly may be causing the problem by "hanging up" the
computer's memory bus (lDA lines). To eliminate this problem, remove all the assemblies
non-essential to basic processor operation.
Remove the CRT assembly and the mainframe top cover; then remove the following assem-
blies:
• 110 Backplane Assembly A2
• Option ROM Drawers, A42, A44
• Printer Control Logic Assembly A51 (if printer installed)
Reinstall the CRT assembly and perform qUick checks 1 and 2 again. The printing test won't
work since the printer assembly is removed.
If the qUick checks now work, then one of the assemblies you removed is probably defective.
Isolate the problem by returning the removed assemblies to the mainframe one at a time.
If some of the quick checks work, the computer is basically functioning and you may need
further information about symptoms from the customer in order to determine the section that
should be tested.
If the printer or tape cartridge qUick checks do not work, the problem may be associated with
that particular section.
If none of the qUick checks have worked the problem can be in the following sections:
• Power supply - check voltage and exchange if necessary.
• Processor/memory control- A15 (LMC), A16 (PMC), A30 (LMC).
• Memory - A28 (LRR), A27 (PRR), A26 (RlW), A46 (200 LRR).
• CRT assembly or A3/A34, see 9845B CRT Section of CE Handbook.
To further isolate one of the sections listed above, use this procedure.
• Check the power supplies for proper voltage output.
• Install the test ROM (09845-65520) and test cartridge (09845-91031) (see 9845B Di-
agnostic Programs).
Note
The A3 or A34 assembly and the CRT assembly must be installed
toperform the test ROM routines.
• Refer to the processor/memory control and memory sections and run the memory tests
(the processor test is run automatically, but can be run by itself)
Note
The Test ROM or test cartridge can fail; when in doubt about test
results, try the system exerciser tape.
09845-90039.
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