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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 # 1057
MODEL: TH-22AT/TH-42AT
SUBJECT: Memory Loss Improvement 

Symptom:

Memory loss can occassionally occur if the following procedure is observed:

1. Program the memory with any desired information.

2. Allow the battery pack to drain down over an extended period of time 
without turning off the transceiver. For example turn the volume control up 
and the squelch off. After approximately 8 hours the battery voltage will 
drop to approximately 3 - 4 vdc.

3. Turn off the POWER SW.

4. Connect a DC voltage supply or a fully charged battery pack.

5. Turn on the POWER SW.

6. Memory will have been lost.

Corrective Action:

Replace microprocessor IC206 with the improved part listed below. 
This part incorporates a software improvement to correct this symptom.

Parts Required:

Qty  Description      Old Part No.      New Part No.     Circuit Description

1    Microprocessor   HD404629B17TF     HD404629B49TF    IC206

Time required for this modification is 60 minutes or less.
Service code A:34 B:X57-347X-XX C:IC206 D:91