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                        Kenwood Service Centers

   Kenwood Service Corporation             Kenwood Service Center, East
   2201 East Dominguez Street              829 Lynnhaven Parkway, Suite 130
   Long Beach, California 90801            Virginia Beach, Virginia 23452
   Telephone 1-310-639-5300                Telephone 1-804-340-1702

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BULLETIN # 1037
MODEL: TH-28A/TH-48A
SUBJECT: CTCSS Tone Error 

Symptom: Several reports were received on early model TH-28/48's concerning 
an inability to access subaudible tone controlled repeaters. This symptom 
only occured when the repeater required the use of any of the following tones:

131.8 Hz
136.5 Hz
173 8 Hz

Corrective Action: A microprocessor software error is responsible for this 
symptom. Replacing microprocessor IC6 on board X53-3400 (TH-28) or 
X53-3410 (TH-48) with the part listed below will correct this symptom.

Parts Required:
Qty    Description     Old Part No.     New Part No.       Circuit Description

1      Microprocessor  HD404629A73H     HD404629A79H           IC6


Caution: This modification requires soldering equipment rated for CMOS 
type circuits. It also requires familiarity with surface mount soldering 
techniques. If you do not have the proper equipment or knowledge do not 
attempt this modification yourself. Seek qualified assistance.

Time required for this modification is 30 minutes or less 
Service Code A: 29 B: X53-340 or X53-341 C: IC6 D: 91