HP 3000 Series Installation And Service Manual page 42

MAINTENANCE
I
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This section contains general servicing information for the HP
30020A Intelligent Network Processor (INP). This information
includes safety precautions, repair philosophy, maintenance aids,
use of the self-test capability, troubleshooting, and field-level
repair.
5-1. SAFETY PRECAUTIONS
Whenever the INP printed circuit assembly (PCA) is installed or
removed, ensure that the computer system's PROCESSOR switch is
se t to OFF.
Whenever the INP peA is being connected or disconnected to a
modem (by attaching or removing the INP-to-modem interconnecting
cable), ensure that the PROCESSOR switch is set to OFF and that
the modem power is also turned off.
Be particularly cautious when selecting the routing for the
longer lengths of the interconnecting data cables. DO NOT run
these cables outdoors! Lightning induced transients can have a
devastating effect on data communication links; and a more direct
lightning strike can, of course, be a very real safety hazard to
personnel as well as to the equipment. Indoor routing must be
planned to avoid sources of electrical "noise", such as arc
welder s.
Failure to observe these precautions could result in damage to
the components of the computer system, the INP, and/or the modern.
5-2. REPAIR PHILOSOPHY
Field repair of the INP PCA is limited to the replacement of the
Random Access Memory (RAM) chips. Any other malfunction must be
remedied on an exchange basis. To exchange~the INP PCA, remove
it from the system and prepare it for reshipment to Hewlett-
Packard in accordance with the instructions in paragraph 5-19.
When troubleshooting procedures have verified a RAM malfunction,
remove the INP PCA from the system and replace the defective RAM
chip as described in paragraph 5-17.
5-1