Fault Isolation Procedure
D-2
V.3600
Modem and Telephone Line Check
Part I
1) Configure the modem for LOCAL ANALOG LOOP WITH
TEST PATTERN. This terminates the local modem telephone
lines into 600 ohms and connects the local modem transmit
output amplifier back to its own receiver through the AGC.
Transmit input data from the terminal is inhibited and is
substituted with a V.52 test pattern.
2) This test checks operation of the local modem modulator and
demodulator circuitry and should be attempted at both local and
remote sites if operators are available.
3) When random errors are present, the TEST PATTERN ERRORS
display counts receive errors.
4) If the circuitry is working properly, the front panel indicators
show the following:
5) Configure the modem for LOCAL ANALOG LOOP to switch
the transmitter back to its normal data input.
6) If the transmit data input is in a mark hold condition, both the TD
and RD indicators should remain off.
7) If the transmit data input is in a space hold condition, both the
TD and RD indicators should come on. All other indicators
should remain the same.
8) If the indicators are correct, the modem is probably operating
correctly.
9) If the preceding tests were not successful, call Technical
Services. Refer to the “Calling Technical Support” section on
page 12-2.
