Distorted/Raspy-Sounding Tx In Ssb Modes.; Tuner Won't Tune On One Or More Bands. - Icom IC-761 Common Questions

is increased toward maximum. Inspection reveals that the internal
power supply is unable to handle the current. Unit runs fine when the
internal power supply is substituted with an external supply.
Cracked solder in the current-sensing circuit of the power supply is
Probable
shutting it down prematurely.
Cause:
Resolder joints at the .0012 ohm resistor, R26 inside the power
Cure:
supply.
This resistor appears as a metal bar soldered to the bottom PC board.
Remarks:
Solder ONLY the edges of the bar before the holes at either end.
Distorted/raspy-sounding TX in SSB modes. Average talk power is
Symptom:
low, even at higher mic gain levels. CW, RTTY and FM seems
normal.
No base bias voltage at driver or PA transistors. Measure voltage at
Probable
bases of driver and PA transistors in TX SSB mode. Should be
Cause:
around .67 volts. 0 volts indicates trouble.
Bad Q6 (2SD880Y) on PA unit. If problem is intermittent, check for
Cure:
bad solder at the legs of Q6, D2.

Tuner won't tune on one or more bands.

Symptom:
Probable
Presets are out of adjustment.
Cause:
Adjust presets.
Cure:
Tuner does not tune on any band. Inspection reveals that only one
Symptom:
motor is turning.
Probable
Bad motor driven transistors.
Cause:
Check motor driven transistors Q1 & Q2, or Q3 & Q4 (depending on
Cure:
the motor that is not turning). If the motor transistors overheated
before they failed, also check related components for failure before
replacing the bad motor driver transistor (or the new drivers will fail
too).
TX oscillation/spurious output, especially on lower bands at lower
Symptom:
power levels.
1) Open parasitic-suppression resistor on PA unit. 2) Burned
Probable
components on the ANT SW unit. 3) Bad drivers or finals.
Causes:
Check the value of R22 (4.7 ohms) on PA unit. (This resistor may
Cure:
look OK but still be open.) Inspect the D4 area of the ANT SW unit
and replace any burned components. If these solutions don't help,
disconnect the cable at J10 on the RF unit and see if the problem
goes away. If it does, the there is a problem with the TX/RX
switching on the RF unit. If disconnecting J10 dies not alleviate the