Maintenance
7-14
STI8 is connected to the Group Execute Trigger signal
(GET) of the 9914 IEEE-488 bus controller (U104).
Tests 105.1-105.6 System Trigger Bus
Failure of Tests 105.1-105.6 suggests a micro DIN board
or digital board error.
System trigger inputs are normally pulled up to +5V
through protection diodes and 1kΩ resistors (CR102-
107, R110-115). The Model 7001 may generate a trigger
on any of the six trigger bus inputs by turning on a FET
(Q100-105) controlled by the associated system trigger
output pin (STO) of the ASIC.
In Test 105.1, STI1 is set up as the trigger input. The
trigger 1 FET is then turned on and off through STO1,
and it is veriÞed that this trips the trigger circuitry in
the ASIC. This test is then repeated for triggers 2-6 in
tests 105.2 - 105.6.
Success indicates proper operation of the trigger bus. A
fault may indicate a defective ASIC, FET, diode, resis-
tor, or open-circuit board trace.
Test 105.7 External Trigger/Channel Ready
Failure of Test 105.7 suggests a DIN or digital board er-
ror.
This test is similar to System Trigger Tests 105.1-105.6
except that there is no internal connection between EX-
TERNAL TRIGGER and CHANNEL READY. Conse-
quently, the meaning of a fault is reversed from that of
Tests 105.1-105.6, i.e., a fault is registered if a trigger
does occur. This would indicate that a short exists be-
tween EXTERNAL TRIGGER and CHANNEL READY.
This fact may be used to test the external BNC connec-
tors. By shorting CHANNEL READY to EXTERNAL
TRIGGER with a BNC cable, Test 105.7 should fail. If it
does not, the signal path is faulty.
Test 105.8 Group Execute Trigger (GET)
Failure of Test 105.8 suggests a digital board error.
Trigger 8 (STI8) is set up as input. The 9914 is then pro-
grammed to generate a GET signal. A failure may indi-
cate a problem with the ASIC or with the 9914.
Tests 105.11-105.18 Trigger Shorts tests
Failure of Tests 105.11-105.18 suggests a DIN board er-
ror.
In Test 105.11, STI1 is programmed as the trigger input.
Each of the other triggers (STI2-STI7 and GET) are pro-
grammed to toggle in turn. If a trigger is detected at
STI1, a short is indicated and the test fails. The test is re-
peated for STI2-STI8 in Tests 105.12-105.18.
Ordinarily, built-in-tests should be run with no exter-
nal connections, however, the Trigger Shorts tests may
be used to verify proper operation at the external
TRIGGER LINK connectors (J1008, J1009). For exam-
ple, by shorting pins 1 and 2, and selecting BIT 105,
faults 105.11 and 105.12 should occur indicating that a
short was detected between system trigger 1 and sys-
tem trigger 2.
7.8 Troubleshooting
The following information is designed to help you
troubleshoot the Model 7001 if a problem develops
which resists diagnosis by the built-in tests. The BIT
does not test to a 100% conÞdence level, but will detect
and identify a majority of problems.
WARNING
Troubleshooting procedures may re-
quire you to apply power and operate
the Model 7001 with the protective
cover removed, thus exposing you to
lethal voltages. To avoid risk of per-
sonal injury, refer any such proce-
dures and testing to qualiÞed
personnel.
7.8.1 Digital board
The digital board contains most of the logic in the Mod-
el 7001, and is tested extensively by the BIT. If the BIT
runs, the digital board (or at minimum, the micropro-
cessor, RAM, EPROM, and EEPROM) is functional.
Artisan Scientific - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisan-scientific.com
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