Preinstallation check. This check is made without wire connections to the telephone set.
a. Set the MODE SELECT switch to AC/LB. Use a screwdriver or a coin. (See Figure 1-17.)
Figure 1-17. MODE SELECT switch.
b. Unlatch the tie-down strap and lift the handset off-hook. Speak into the microphone and
listen for sidetone. You should hear very low level sidetone or no sidetone at all. Press each of the 16
keys on the keysender pad one at a time. The sound level (if any) of each key tone should be very low.
Place the handset on-hook.
c. Set the MODE SELECT switch to PT-PT. Lift the handset off-hook and speak into the
microphone. Wait at least four seconds before speaking. Listen for the sidetone level. It should be
normal sidetone. Press each of the 16 keys on the keysender pad one at a time. The sound level of each
key tone you hear should be a little lower than the sidetone level of your voice. Place the handset on-
d. Press each binding post until its slot is visible and place one 1000-ohm resistor between one
XMIT (black) binding post and one RCV (red) binding post. Release the binding post to secure the
resistor. Then place another 1000-ohm resistor between the other XMT and RCV binding posts. (See