5902 Bell 202 Modem Hardware Manual
October 19, 2007
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MODEM MODE
NORMAL
TEST
TST switch
Open
closed
6.2.1
Basic Functional Test
This test checks that the modem CPU; the configuration switches; the CS and KEY LEDs; the RCD
input; and the KEY output are functioning. External wiring is required to test the RCD input and the
KEY output.
WARNING:
Disconnect the modem from the DTE device and the communication system to
prevent interference during this test.
To select this test mode:
Turn off the power to the modem.
Close the TST switch.
Apply power to the modem.
6.2.1.1
Switch and LED Test
The CS and KEY LEDs will be on when power is applied. The CS and KEY LEDs will toggle state
when any configuration switch is toggled. To test the configuration switches:
Toggle switches on at a time.
Observe that the CS and KEY LEDs toggle state.
Return the switch to it’s original position.
6.2.1.2
RCD and KEY Test
The CD LED shows the status of the RCD input. If the RCD input is true, the CD LED will
illuminate. The KEY output is set to the same state as the KEY led. A good way test the RCD input
and KEY output is:
Wire the KEY output to the RCD input.
Toggle any configuration switch to cause the KEY LED and output to toggle.
Observe that the RCD input LED is changes states when the KEY output LED changes state.
To exit this test mode, return the TST switch to the open position. The modem will reconfigure itself
according to the configuration switches and immediately begin operation.
6.2.2
Tone Transmission Test
This test is used to continuously transmit alternating MARK and SPACE tones for aligning radio
communication systems, and adjusting modem transmit and receive signal levels.
WARNING:
This test mode will transmit tones continuously, without anti-streaming. It is
recommended the DTE be disconnected from the modem to prevent reception of
false data.
To select this test mode:
Apply power to the modem.
Open the FDX switch (select half duplex mode).
