IBM System/34 Maintenance Manual page 167

e
Short Circuit Cable
••••••••••
•••••• 111111.
'1 •••••
11.11.
, •••••• rn.rn.
I • • • • • •
.,~!I
..
• • • • • • ' (see Note 1)
I
Notes:
. . A small change in the signal level caused from a
terminal (with the Cable Thru feature) 131 meters
(430 feet) from the end of the cable being
checked. The change at . . is also shown in
0
and • .
II
A change in the signal level caused from the last
terminal on the cable 495 meters (1625 feet) from
the end of the cable being checked.
Note: A change in the signal level of more than 10
percent usually indicates a problem.
. . Same as • in • but with the B time base now
set to 0.2 JLs •
B
A change in the signal level caused by a short
circuit cable 170 meters (560 feet) from the end of
the cable being checked.
1.72 JLs X 99 meter.s = 170 meters }
or (see Note 2)
1.72 JLS X 324.7 feet
=
560 feet
. . Same as . . in
O.
. . A change in the signal level caused by an open
circuit cable 170 meters (560 feet) from the end of
the cable being checked.
1.72 JLS X 99 meters
=
170 meters}
or (see Note 2)
1.72 JLS X 324.7 feet
=
560 feet
. . Same as . . in • but with the B time base set at
1 JLs.
Note: Always change the B time base to show
only one change in the signal level so that you can
more easily determine the time on your
oscilloscope.
1. The A time base is always set for 10 J1.S and Channel 1 is always set for 0.2 volts/division.
2. The reflection for the shorted cable and for the open cable occurs at 8.6 divisions.
Therefore, t is equal to 1.72 J1.S (8.6 x 0.2).
Figure 11-8. Sample Oscilloscope Signals
12
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