Note: This service bulletin is meant for technical per-
sonnel with experience working on solid state com-
munications equipment. Damage caused by im-
properly installing this modification may cause
ICOM to charge for subsequent repairs to the
product. ICOM does not warrant this modification.
Bulletin #: 13889-004
Date: May 1, 1989
Subject: Elimination of possible faint pulse noise from
speaker when radio is in power save mode
Information: The power save mode employs a circuit which
creates a high level square wave signal used in
the power save function. This modification alters
the square wave characteristic to eliminate the
1. Remove the covers from the radio and locate the main board.
2. Locate C-749 and replace it with a 2.2 uf 16 V tantalum chip capacitor.
3. Reassemble the radio, power up and allow the unit to enter the power save mode.
4. Check to see that the pulse type noise has been eliminated.
5. Replace the covers and return the radio to service.