TROUBLESHOOTING
Problem: you are having difficulty transmitting on the radio.
Reason:
the pilot’s and co-pilot’s microphone jacks may have been incorrectly wired.
Solution:
check wires
2
,
3
,
7
,
8
, and
17
, and re-wire if necessary.
Problem: the sidetone is distorted while transmitting on the radio, even though the tower receives you
loud and clear
.
Reason:
a distorted sidetone while transmitting may be due to improper shielding of the aircraft antenna
cable.
Solution:
have a radio technician check the shielding of the antenna cable.
Problem: you do not hear a sidetone while transmitting on the radio.
Reason:
the radio sidetone level may be adjusted too low or turned off.
Solution:
increase the radio sidetone output.
Reason:
the radio may not have been designed with a sidetone output or the sidetone output may not have
been connected during radio installation.
Solution:
set
DIP
switches
1
,
2
, and
3
to the
ON
position to allow the intercom to artificially generate a sidetone
when you transmit (see Case Top Removal on page 9 of this manual for location of DIP switches
inside the intercom case).
NOTE:
when DIP switch
1
is in the
ON
position and the
Isolate
switch is in the
Isolate
position, the pilot will not
hear his sidetone while transmitting, but passengers will be able to monitor his transmissions. The “receive”
functions, however, will work normally, as described in the Pilot Isolate Switch section on page 12 of this manual.
Problem: the unit is completely dead.
Reason:
there may not be voltage available through the power supply lead (pin 20).
Solution:
restore voltage by reconnecting pin 20.
Reason:
the fuse or circuit breaker may not be intact.
Solution:
repair or replace the fuse or circuit breaker.
Reason:
one or more wires may have been incorrectly numbered during installation, causing incorrect
wire connection.
Solution:
re-connect wires as shown in Figure 7 on page 5 or Figure 6 on page 4.
Reason:
the headphones may not be plugged in all the way.
Solution:
securely plug in the headphones.
Reason:
the headset volume may not be turned up.
Solution:
turn up the headset volume.
Reason:
the headphone plugs may be corroded.
Solution:
shine up the headset plugs with steel wool or crocus paper.
Reason:
the aircraft master switch may be turned off.
Solution:
turn on the aircraft master switch.
Reason:
the squelch may not be set correctly (the 403 and 403d intercoms are silent when muted).
Solution:
reset the squelch control.
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