Icom IC-756 - Maintenance and Troubleshooting; Troubleshooting Common Issues; Internal Views; Component Layout Diagrams

63
10
MAINTENANCE
■ Troubleshooting
The following chart is designed to help you correct
problems which are not equipment malfunctions.
If you are unable to locate the cause of a problem or
solve it through the use of this chart, contact your
nearest Icom Dealer or Service Center.
PROBLEM POSSIBLE CAUSE SOLUTION REF.
POWER
Power does not come on
when the [POWER] switch
is pushed.
•DC power cable is improperly connected.
•Fuse is blown.
•Reconnect the DC power cable correctly.
•Check for the cause, then replace the fuse with
a spare one.
(Fuses are installed in the DC power cable
and the internal PA unit.)
p. 16
p. 64
RECEIVE
No sound comes from the
speaker.
•Volume level is too low.
•The squelch is closed.
•The transceiver is in the transmitting condition.
•Rotate [AF] clockwise to obtain a suitable
listening level.
•Rotate [RF/SQL] to 10 o’clock position to open
the squelch.
•Push [TRANSMIT] to receive or check the
SEND line of an external unit, if desired.
p. 1
p. 2
p. 1
TRANSMIT
Transmitting is impossi-
ble.
•The operating frequency is not set to a ham
band.
•Set the frequency to a ham band. p. 23
Sensitivity is low. •The antenna is not connected properly.
•The antenna for another band is selected.
•The antenna is not properly tuned.
•The attenuator is activated.
•Reconnect to the antenna connector.
•Select an antenna suitable for the operating
frequency.
•Push [TUNER] for 2 sec. to manually tune the
antenna.
•Push [ATT] one or more times to select “ATT
OFF.”
—
p. 3
p. 39
p. 3
Receive audio is distorted. •The operating mode is not selected correctly.
•PBT function is activated.
•Noise blanker function is activated.
•Preamp is activated.
•The noise reduction is activated and the [NR]
control is set too far clockwise.
•Select a suitable operating mode.
•Set [TWIN PBT] to the center position.
•Push [NB] to turn the function OFF.
•Push [P.AMP] once or twice to turn the function
OFF.
•Set the [NR] control for maximum readability.
p. 25
p. 25
p. 26
p. 3
p. 26
The [ANT] switch does not
function.
•The antenna switch has not been activated. •Set the antenna switch in set mode to “AUTO” or
“MANUAL.”
p. 58
SCAN
Programmed scan does
not stop.
•Squelch is open.
•[RF/SQL] is assigned to RF gain control and
squelch is open.
•Set [RF/SQL] to the threshold point.
•Reset [RF/SQL] control assignment and set it to
the threshold point.
p. 2
pgs.
2, 56
Output power is too low. •[RF POWER] is set too far counterclockwise.
•[MIC GAIN] is set too far counterclockwise.
•The antenna for another band is selected.
•The antenna is not properly tuned.
•Rotate [RF POWER] clockwise.
•Set [MIC GAIN] to a suitable position.
•Select an antenna suitable for the operating
frequency.
•Push [TUNER] for 2 sec. to manually tune the
antenna.
p. 2
p. 1
p. 3
p. 39
No contact possible with
another station.
•RIT or ∂TX function is activated.
•Split frequency function and/or dualwatch are
activated.
•Push [RIT] or [∂TX] to turn the function OFF.
•Push [SPLIT] and/or [DUALWATCH] to turn the
function OFF.
p. 5
pgs. 4,
30, 31
Transmitted signals are
distorted.
•[MIC GAIN] is set too far clockwise. •Set [MIC GAIN] to a suitable position.
p. 1
Repeater cannot be
accessed.
•Split frequency function is not activated.
•Programmed subaudible tone frequency is
wrong.
•Push [SPLIT] to turn the function ON.
•Reset the frequency using set mode.
p. 4
p. 57
Programmed scan does
not start.
•The same frequencies have been programmed
in scan edge memory channels P1 and P2.
•Program different frequencies in scan edge
memory channels P1 and P2.
p. 43
Memory scan does not
start.
•2 or more memory channels have not been
programmed.
•Program 2 or more memory channels.
p. 43
Select memory scan does
not start.
•2 or more memory channels have not been
designated as select channels.
•Designate 2 or more memory channels as select
channels for the scan.
pgs.
42, 50