Clear-Com HB-704 - Manual (Page 17)

H B - 7 0 2 / H B - 7 0 4 T W O - A N D F O U R - C H A N N E L H E A D S E T S T A T I O N S
3 - 3
(3) Plug P3 is missing on circuit
board. (3) Plug P3 must be installed in the
J3 jack if the EB-4W or EB-TW
option is not used.
Hum or buzz in system Inductive pickup caused by close
proximity of this headset station or
connected stations to power lines or
transformers. Relocate the offending unit or
wiring. If the cable run is
exceptionally long, consider adding
and using the EB-4W four-wire
option module. (Requires an
additional four-wire interface at the
opposite end of the “long run.”)
System feedback (acoustical) (1) Listen level control at this station
or another station is set too high. (1) Adjust.
(2) Sidetone null control at this
station or another station is not
adjusted correctly. (2) Adjust. Refer to section
regarding “Front Panel.”
(3) Channel not terminated. (3) Set the main station or power
supply termination switch for that
channel to the on position.
(4) The channel switch is set to an
unconnected channel. (4) If less than the maximum number
of intercom lines are to be
connected, link unused intercom
inputs to a connected input with
jumper wires.
(5) A headset extension cord was
used. (5) Headset extension cords are not
recommended because they increase
crosstalk.
Excessive crosstalk (1) High DC resistance in ground
return. (1) Use heavier cable; add additional
conductor(s) to ground return. If the
cable run is exceptionally long,
consider adding and using the
EB-4W four-wire option module.
(2) Multi-channel cable pairs are not
individually shielded. (2) Replace cable with individually
shielded pairs.
(3) Headset cables are not wired
properly or shielded properly. (3) Correct wiring. Use headsets
with properly shielded wiring.
SYMPTOM CAUSE SOLUTION