Common failures IC-706

Symptom: Low RX sensitivity on 2-meters.

Probable Cause: Burned D6 on PA unit.

Cure: Replace D6 (MA862).


Symptom: No TX power output on an HF band.

Probable Cause: Bad filter relay.

Cure: Locate and replace faulty filter relay (will be type AHY-103).


Symptom: Low/distorted RX audio.

Probable Cause: Burned foil trace on PLL unit.

Cure: Repair SPE (ground) foil trace on PLL unit.


Symptom: Low TX output on HF & 6-meters.

Probable Cause: Shorted D18 and Q1 in filter unit.

Cure: Replace D18 (DAP222) and Q1(2SC4081).


Symptom: Inadequate mic gain.

Cure: Install field mod on main unit: Change value of R236 from 27k, to 68k-82k. [The higher the resistor value, the greater increase in mic gain].


Symptom: Thin-sounding mic audio.

Cure: Install field mod inside HM-103: Remove rubber gasket from beneath mic element.


Symptom: Off frequency in FM TX.

Probable Cause: FM VCO lock voltage needs adjustment.

Cure: Adjust FM VCO lock voltage for 1.5 volts as per service manual.


Symptom: Unit is stuck in TX mode.

Probable Cause: Shorted T/R switch transistor.

Cure: Replace shorted Q32 in main unit.


Symptom: Radio won’t power up.

Probable Cause: Burned ground foil trace in flex cable.

Cure: Replace flex cable EP2 at main board.