Radio Seems To Be Stuck In 'Scan' Mode.; Loud, High Pitched Squeal Emanates From Inside Radio. - Icom IC-761 Common Questions

problem, then most likely either the drivers or PA transistors are bad,
especially if the ALC meter deflection is low.
Spurious output may be caused by incorrect band switch voltage to
Remarks:
the low-pass filter unit, or even faulty/burned components on the
filter unit itself. The above causes should be ruled out first, however,
since low-pass filter failures are uncommon in the IC-761.
Radio seems to be stuck in "scan" mode.
Symptom:
Probable
Bad IC2 on the logic unit.
Cause:
Replace IC2 (RP5G01-007)
Cure:
Intermittent display. S-meter may peg and RX/TX may disappear
Symptom:
when the unit is in the failure mode.
Cracked solder beneath the DP-6 DC-DC converter IC (IC1) on the
Probable
display unit.
Cause:
Carefully remove the DP-6 converter IC from the display unit and
Cure:
resolder the pins of the IC to its circuit board. Then reinstall the
DP-6 back on the display unit.
VFO tuning is erratic, sometimes skips frequencies in a certain area
Symptom:
if VFO knob travel. Least significant digit in frequency display
sometimes "flutters" back and forth instead of changing
incrementally when the VFO knob is turned slowly.
Probable
Bad rotary encoder.
Cause:
Substitute rotary encoder with a known good one. It is recommended
Cure:
that the rotary encoder be replaced as a complete assembly if it is
bad.
If the unit tunes in only one direction, i.e. either up or down, there
Remarks:
may be a problem on the logic unit.
Loud, high pitched squeal emanates from inside radio. May be
Symptom:
intermittent.
Probable
DC-DC converter transformer has a loose core.
Cause:
Replace DP-6 on the display unit.
Cure:
A whine emanates from inside radio in TX only at certain power
Symptom:
levels. Transmitter works ok.
Probable
Loose core in DC-DC converter transformer inside power supply.
Cause:
Replace T2 on reg. unit inside power supply.
Cure: