Service Model 8901B
Catastrophic Failures
Begin troubleshooting catastrophic failures by performing the troubleshooting checks on Service Sheet
BD1. The simple procedures there
take
only
a
few minutes and will quickly differentiate a control
(digital) problem from a hardware (analog) problem. The checks give cross-references to the detailed
block diagrams (Service Sheets BD2
to
BD5) which then direct you
to
the necessary schematic.
The troubleshooting information found on all service sheets consists
of
a series of performance checks.
The purpose of the checks
is
not
to
identify which circuit
or
component
has
failed but rather to verify
whether the assembly
or
circuit
is
operating correctly. Information on the possible cause of failure is
given in the form of hints whenever they
can
be given reliably. The limits given in the troubleshooting
checks are rather loose
to
facilitate the use
of
general-purpose equipment (usually
an
oscilloscope).
If
a slightly out-of-tolerance condition
is
suspected, the test can usually be run more rigorously paying
greater attention to measurement accuracy.
Troubleshooting
on
the block diagram level normally utilizes User and Service Special hctions, while
troubleshooting on the schematic level often utilizes Direct Control Special Functions. Direct Control
Special F’unctions will require some study
of
their operation before using them for the first time.
8A-6
To Next Page
Loading...
