Fuse Replacement; Clock Backup Battery Replacement - Icom IC-756 Instruction Manual

PROBLEM
The displayed frequency
does not change properly.

Fuse replacement

If a fuse blows or the transceiver stops functioning, try
to find the source of the problem, and replace the dam-
aged fuse with a new, rated fuse.
CAUTION:
Disconnect the DC power cable from
the transceiver when changing a fuse.
The IC-756 has 2 types of fuses installed for trans-
ceiver protection.
• DC power cable fuses ............................... FGB 20 A
• Circuitry fuse ............................................... FGB 5 A
CIRCUITRY FUSE REPLACEMENT
The 13.8 V DC from the DC power cable is applied to
all units in the IC-756, except for the power amplifier,
through the circuitry fuse. This fuse is installed in the
PA unit.
q Remove the top cover as shown on p. 61.
w Remove 11 screws from the PA shielding plate,
then remove the plate.

Clock backup battery replacement

The transceiver has a lithium backup battery on the
inside of the front panel for clock and timer functions.
The usual life of the backup battery is approximately 5
years.
When the backup battery is exhausted, the trans-
ceiver transmits and receives normally but cannot re-
tain the current time.
POSSIBLE CAUSE
• The dial lock function is activated.
• A set mode screen is selected.
• The internal CPU has malfunctioned.
SOLUTION
• Push [LOCK] to deactivate the function.
• Push [ EXIT] one or more times to exit the
(F-5)
set mode screen.
• Reset the CPU.
DC POWER CABLE FUSE REPLACEMENT
e Replace the circuitry fuse as shown in the diagram
below.
r Replace the PA shielding plate and top cover.
Circuitry fuse (FGB 5 A)
10
MAINTENANCE
REF.
p. 5
pgs.
10, 53
p. 21
20A fuse
64