Modem Indicators; Troubleshooting Procedure; Flow Charts - Simplex 2120 Service Instructions Manual

TROUBLESHOOTING
As far as troubleshooting the converters and modems are concerned, we only want to isolate the problem either
to our equipment - which we can replace - or to telephone company equipment. You'll know when a trouble
exists because the BMUX will report primary communications failures (COMM
FAILED PRI) for all transponders
on the far side of the telephone line.
MODEM INDICATORS
There are three LEDs on the modem's front panel that you should observe during troubleshooting:
l
The
RCV
LED, which should be rapidly flashing.
l
The
XMT
LED, which should also be rapidly flashing.
AND
l
The
DSR
LED, which should be on steadily when the modem is powered up.
TROUBLESHOOTING PROCEDURE
The flowcharts on the following pages will help you isolate problems to the converters and FSK modem, or to the
telephone lines. Each flowchart has a figure number. Any given flowchart contains all the information necessary
to perform any tests or checks called out on that flowchart. Follow the flowcharts exactly, and when you reach
a figure reference - PROCEED DIRECTLY TO THE REFERENCED FIGURE.
FLOWCHARTS
Symbol Definitions
. u
\
0
0
This symbol is used to request a certain act, test of performance. Perform the action
before continuing.
This symbol will contain a simple question - usually based on the action that
preceded it. Two points will be labeled - one point "yes", the other "no". Exit at the
point which provides the correct answer to the question.
This symbol indicates that the steps are continued on another flowchart. The flowchart
figure number will be written inside the symbol. Flowchart figure numbers appear at the
bottom of each flowchart. A similar symbol with a reference to the previous flowchart
figure number will appear on the figure indicated.
The reference symbol is used when additional information is available, and it is always
connected to an action symbol. Refer to the referenced material prioer to performing
the action.
This symbol indicates that the steps are continued on another part of the same page.
The number within the circle will match the number in a circle at the point where the
flow continues.
This symbol indicates that a very serious malfunction exists and additional assistance
is required. The information within the symbol will recommend a source of aid.
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