
9000A-006 Service
3-4
Procedure, but only disconnect the largest of the four ribbon cables from the
Troubleshooter main pcb assembly and the Signature Module. Install an SYP 6520 PIA
(part number 536318) in the vacant socket to allow bypassed communication between the
Troubleshooter and the Interface Pod.
NOTE
This type of PIA exists on the Signature Module; however, moving the PIA
to the main pcb allows the possibility of moving the problem from the
Signature Module to the main pcb of the Troubleshooter.
With the Signature Module removed from the data/handshaking signal path of the
Interface Pod, normal pod operation should be restored. Verify pod operation by
performing a pod self-test or any other test that prompted disconnection of the Signature
Module. If the Interface Pod operation now appears normal, the problem exists in the
control section of the signature module.
A key device in the control section is the PIA (U2). Verify operation of U2 by removing it
(power off) and using it to replace the PIA previously installed in the connector socket on
the main pcb assembly. With the PIA from the Signature Module installed on the main pcb
assembly, repeat the test performed in the previous paragraph. If the test fails, the PIA is
defective. But, if the test does not fail, it probably is good, although the test results are
inconclusive. To verify operation of the PIA, replace it in the Signature Module and
proceed to Signature Troubleshooting Procedures.
SIGNATURE TROUBLESHOOTING PROCEDURES
3-12.
Getting Started
3-13.
The most efficient method of locating faults within the Signature Module is to employ a
second Troubleshooter, hereafter referred to as the test Troubleshooter, equipped with the
Asynchronous Signature Option to read signatures at various points on the module.
During the signature reading operation, the Troubleshooter in which the defective module
is installed is used to stimulate the module with programs 1 and 2 supplied on side B of the
cassette tape.
The valid signatures with the corresponding test nodes are listed in tables in Section 5,
along with the schematics. Table 5-1 contains signatures for the control and gate sections
(defined in Section 2, Theory of Operation) of the defective module when program 1 is
running. Table 5-2 contains valid signatures for the signature, events, and waveform
sections (also defined in Section 2, Theory of Operation) when program 2 is running.
Signatures are not provided for every possible test node on the module, but signatures are
given for particular nodes in each functional section. When you find an invalid signature,
trouble is indicated in that section, and you can perform further testing with the aid of an
oscilloscope, the schematic diagram, and the Theory of Operation section.
Stimulation of the defective Signature Module (UUT) requires that its five Clock Module
leads and Data Probe are properly connected. The connections allow the Signature
Module to respond to the test stimulus. The connections listed first allow the defective
module to receive the control and data signals necessary to stimulate gate and control
sections of the defective module.
Summary of Contents for 9000A-006
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