Intermitient Failures Troubleshooting; Guide; Exercisers; Failure Isolation - IBM 5100 Maintenance Information Manual

Intermittent Failures Troubleshooting
Guide
This guide is a summary of the 5100 diagnostics and a
guide for troubleshooting intermittent failures.
5100 DIAGNOSTIC SUMMARY
The 5100 diagnostics start testing a small area of the
machine and gradually expand to test the complete
system. Each diagnostic tests a specific area and
overlap each other. For example, the ROS diagnostic
tests ROS but, because ROS contains the printer
microinstructions, some printer operations are indirectly
tested. Normally the tests should be run in the
sequence shown on the Diagnostic Summary Chart.
However, in the case of intermittent failures, this
sequence can be altered depending on:
- The information you have concerning the failure.
Whether or not this is the first call.
- How frequently the failure occurs.
There are three categories of diagnostics:
• Exercisers
• Failure isolation
• Utilities'
Exercisers
The diagnostics that fall into the exerciser category are
the bring up and ROS resident programs. These
programs exercise the machine and halt when failures
occur. Now you can use the MAPs to locate the failure
or, if the failure is intermittent, use the Diagnostic
Summary Chart on the facing page to assist you in
isolating to the failing FRU.
Failure Isolation
The tape resident diagnostics provide failure isolation.
These diagnostics are integrated into the MAPs and are
called MDls. The MDls locate failing FRUs associated
with the printer, the internal tape unit, the 5106 Auxiliary
Tape Unit, and Communications/Serial I/O features.
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Utilities
Utilities are contained in the ROS resident diagnostics.
They are used to display and alter read/write storage, to
branch, to copy tape to read/write storage, and to copy
read/write storage to tape. These diagnostics are not
covered in this guide; refer to ROS Resident Programs
and Tests in this section.
DIAGNOSTIC SUMMARY CHART
The Diagnostic Summary Chart shows the diagnostics,
the areas tested, the operating instructions, and the
normal sequence of use. The chart does not show all of
the diagnostic capabilities, just those primarily used for
failure isolation. When reviewing the chart, note how
the diagnostics use the building block concept. That is,
they begin by testing the basic machine functions and
then proceed until they have tested the most
sophisticated functions.
The bring up diagnostic does not loop automatically;
therefore, four of its tests are repeated as ROS resident
diagnostics CMD 2, 3, 4, and 5.
Looping on a MOl allows repetitive testing of a
complete device. Failures during looping cause a branch
to a subsection of the M DI that checks a smaller area of
the device. You can loop on subsections of the MOl to
further isolate the failure. However, it is important to
start with one of the displayed OCP2 options because
these tests are sequence sensitive.