Icom IC-575 (IC 575 IC575) transceiver mods reviews software and diagrams

PREPARATION:

1. Disconnect mains lead and antenna lead.
   
   
2. Remove the EIGHT screws from the TOP COVER.
   
   
3. Remove the FOUR side screws. (Two left & two right).
   
   
4. Remove the top cover.
   
   
5. Remove FOUR screws holding the PA/REG UNIT. (Two at top front & two at rear).
   
   
6. Carefully hinge PA/REG UNIT back out of the way.
   
   
7. Remove shield to LOGIC UNIT. (Unit on right hand side).

MODIFICATION:
Refer to diagram above.

This modification is done to the LOGIC UNIT in three parts;

1. Cut the red wire to J3
   
   
2. Add a diode (small signal type ie; 1N914 etc.) between PIN 18 of IC5 74HC244 [ANODE END OF DIODE] and the CATHODE of D10 [CATHODE END OF DIODE]. The back-up battery may have to be carefully levered out of the way in order to gain better access to PIN 18 of IC5.
   
   
3. Add a diode (small signal type ie; 1N914 etc.) between the pad where D25 CATHODE would go [CATHODE END OF DIODE] and the pad just opposite D20 CATHODE [ANODE END OF DIODE]. See diagram for details. (that's coming later)