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Measuring
Logic
(Functional
Level
7)
•
ASIC
Stimuli
Figure 5-19
Pinning
diagram
for
U56 and
U58.
-
Run
the
ASIC
tests,
Test 7
and
8.
NOTE:
Test 6 runs
automatically without
stimuli signals.
-
Set
the oscilloscope
to
2
V/div
and 50
|i,s/div.
-
Check
all
signals
on
U56
and U58.
Use P5
to
trigger
the
oscilloscope,
see
Figure 5-19.
-
The
timing
diagram
in
Figure 5-18
shows
the signals
ge-
nerated by the
stimuli
program.
If
you
find
any
fault,
continue with
traditional
troubleshoo-
ting
techniques
and
replace defective
circuits.
See
also
Chapter
4,
Circuit
Descriptions,
Counter
Circuits.
The
following tests
should
be
done
with the
standard
PROM
Installed
in
the counter.
-
Switch on
the counter.
-
Connect an
arbitrary
signal
to
the
EXT
ARM
input,
J5
at
the rear panel.
-
Trace
the signal
from J5
to
U58
pin
27.
-
Connect
a
10
MHz
signal to
the
REFERENCE
IN
input,
J6
at
the rear panel.
-
Trace
the signal
from J6
to
U56
pin
38.
-
Select
EXT
REF.
-
Trace
the
signal
from
U56
pin
35
to
the 10
MHz
OUT,
J7
at
the rear panel.
-
Trace
the signal
from
U58
pin
41
to
GATE OPEN
output,
J4
at
the rear panel.
-
Trace
the
signal
from
U58
pin
37 and 38
to
J17
pin
30
and 34
at
the
front
panel
and
to
the
display
and
key-
board
board.
If
you
find
any
fault,
replace the defective
circuits.
See
also
Chapter
4,
Circuit
Descriptions,
Counter
Circuits.
Figure 5-18
Timing diagram
for
ASIC
stimuli
test
program.
Troubleshooting
5-13
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