Diagnostics Overview; Kernel Tests - Tektronix 11A52 Service Manual

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4
Diagnostics
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This section explains the self-test and diagnostic systems used in the 11AS2 Two Channel Amplifier. The
reader needs a familiarity with the general operating principle of the amplifier, some knowledge of its
electrical functioning, and a working knowledge of the amplifier
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oscilloscope interface.
Diagnostics Overview
This firmware contains comprehensive test and diagnostic routines to detect and help locate hardware faults.
These test and diagnostic routines are grouped into three categories:
a) Power-up Kernel testing
b) Self-tests (Invoked by oscilloscope)
c) Diagnostics (Invoked by oscilloscope)
Kernel Tests
When the amplifier is powered-up and the CPU has reset, the amplifier begins a sequence of test routines to
determine if its crucial systems are operating properly. If any of these tests fail, it is unlikely that the
amplifier will operate correctly in a system. Any failure is indicated by flashing a specific fault code on the
front panel CH 1 and CH 2 LEDs. This fault code indicates which kernel test is failing. The fault code is read
using the following procedure:
If
the amplifier kernel tests detect any fault, a fault code will be displayed by flashing the CH 2 LED eight
times. Each time the CH 2 LED
turns
on, count the occurrences. If the CH 1 LED is lit during a cycle of the CH 2
LED, the test corresponding to the count accumulated so far is the one which failed. Refer to the timing
diagram in Figure 4-1 for a sample LED fault code. The timing diagram shows that test number 2 has failed.
11AS2 Extended Service Manual
4-1