Data General NOVA 4/C Field Engineering Maintenance Manual page 12

PREFACE
This manual is a guide to troubleshooting and repairing
NOVA 4/C computers at the field replaceable unit level,
commonly referred to as "board swapping".
It is organized around four major sections.
Part 1 is a product description, which
e Introduces the major assemblies and explains how they
interconnect
e Defines the field replaceable units
e Lists the related documentation
¢ Explains how to use the consoles.
Part 2 is devoted to troubleshooting. It explains both how
to perform initial checkout and how to repair a system
that failed after normal operation. It describes procedures
for finding a failing field replaceable unit using:
« Visual checks
e The CPU's self-test feature
e Reliability and diagnostic test programs
e Simple manual tests.
These procedures, written in a "cookbook" manner, should
allow the field engineer to repair most failures in a
minimum period of time.
Part 3 contains reference information about the power
supplies and the major printed circuit boards. This
information is useful when you troubleshoot with an
oscilloscope.
Part 4 provides detailed mechanical replacement
procedures for each field replaceable unit.
WARNING: The power supplies in these units have
hazardous voltages on their printed circuit boards.
They should be repaired only by trained service
personnel.