TM 11-7025-234-23
o
7 DC BUS switch
When pressed, causes TEST indicator to blink, isolates
local data terminal from modem by looping terminal
data and clock output back to the input, and connects
local modem receiver output data to transmitter data
input. The remote modem receives self transmitted
data back through the local modem and telephone lines.
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8 AUD BUS switch
When pressed, causes TEST indicator to blink and
connects receive telephone line through receiver AGC
to transmit output amplifier. Transmit audio signal,
which normally feeds the transmit output amplifier, is
connected to the receiver input, post-AGC. This
allows the local data terminal to receive output data
back through the local modem transmitter and receiver,
and provides an audio loopback for the remote modem
through the local modem transmit output amplifier and
receiver AGC circuits. This switch has no effect when
the modem is a multipoint master.
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9 LAMP CHK switch
Pressing the momentary-contact LAMP CHK switch should
light all the modem indicators. Operation of the LAMP
CHK switch does not affect normal data transmission
and reception.
Figure 2-2.
Mother Board Controls and Indicators (2 of 2)
2-3
