Simplex 2120 Service Instructions Manual page 7

OBSERVE THE RCV
AND XYT LEDS.
I
WHEN TELCO FINISHES I
REPAIRS, THE SYSTEM
SHOULD FUNCTION
PROPERLY.
THE XMT LED ON THE
MODEM MUST BE OFF
IF YOU HAVE REACHED
THIS BLOCK.
I
YES
+
POSSIBLE PROBLEM WITH
TELEPHONE LINES. CONTACT
TELCOANDHAVETHEMTEST
IN ACCORDANCE WITH THE
INSTRUCTIONS AT THE
BOlTOM OF THIS PAGE.
I
CHECK THE FOLLOWING AT THE
FAR-END:
1
. COMM CHANNEL OPEN
. BAD TRANSPONDER(S)
. BAD FAR-END MODEM
. BAD FAR-END CONVERTER
TROUBLESHOOT AS APPROPRIATE.
REPLACE MODEM
ON BMUX END.
,y,, i
,.,I
.: ,:,
REPLACE THE
FAR-END MODEM.
+
1
NO
WHEN TELCO FINISHES
REPAIRS, THE SYSTEM
SHOULD FUNCTION
PROPERLY.
FIGURE 4
SPECIAL NOTE TO TELEPHONE LINE TROUBLESHOOTER
The FSK modem being used is a Bell type 202T. The analog loopback switch is visible on the modem's front
panel. To access the digital loopback switch, press down on the flat part of the front panel at the base of the
modem.
Be sure to return the switches to their normal positions after testing.
5