HP 3000 SERIES II System Service Manual page 87

MAINTENANCE PROCEDURES
I~
4-1. INTRODUCTION
This section includes general servicing information, safety precautions, repair philosophy, memory
chip replacement information, and PCA jumper information. Principles of operation and principal
servicing points of the memory module are also presented in this section.
4-2. SAFETY PRECAUTIONS
When performing maintenance on the system, observe all cautions and warnings placarded in the
cabinet and included in this manual. Failure to observe the warnings could result in injury or death.
WARNING
Dangerous voltages are present in the HP 3000 Computer
System power control module and cabinet ac power dis-
tribution. Exercise extreme caution when working in these
areas when covers and panels have been opened for
troubleshooting convenience.
WARNING
Two men are required to remove the HP 30310A Power
Supply from its mounting hinge in an equipment cabinet.
This power supply weighs 50 pounds (22.7 kilograms).
4-3. REPAIR PHILOSOPHY
The repair philosophy for the system is to replace a defective PCA, and not troubleshoot to the
defective component. The exceptions are the Semiconductor Memory Array PCA (30008-60002) and
the Fault Correction Array PCA (30009-60001). These PCA's are repaired to the component level.
Repair of these PCA's should only be performed by CE's specifically trained for this task.
The repair philosophy for the three power supplies (HP 30310A, HP 30311A, and HP 30312A)
limits field repair to replacing open fuses. If any other problem arises with a power supply, the
entire unit should be replaced. Power supplies are non-repairable items maintained on an exchange
basis.
4-4. GENERAL SERVICING INFORMATION
A prime consideration to be remembered when servicing the HP 3000 Series II Computer System is the
power requirement of the memory module. Unlike core memory, data will be lost or altered when
power is removed from this dynamic solid state memory. A battery back-up power supply (HP 30311A)
is installed in the system to provide power to the memory module when the system is turned off for
maintenance, for PCA replacement, or when system AC input power is interrupted. A full
description of this power supply, its function, operation, adjustment procedures, and associated
lamp indications, is contained in Appendix B.
JAN 1977
4-1