Symptom:
Due to a recent rule change by the FCC it is no longer possible to supply transceivers, or provide replacement microprocessor that would allow a transceiver to receive in the 800 MHz band.

Corrective action:
The microprocessor program of IC5 has been modified to prevent 800 MHz band reception. Production has been changed beginning with serial number lot 510xxxx. Units produced after this point will not be capable of 800 MHz reception.

Parts required:

Qty   Description                Old part No.      New Part No
 1    Microprocessor             HD6433388A22F     HD6433388A25F

Procedure:
When ordering a replacement microprocessor you will be supplied with the new version. Please make sure your customer understands the limitations of this new



23-04-2000 Microprocessor Change, TM642/742/942
Author: Kenwood Communication, inc.

Symptom:
Reports of problems with microprocessor lock-up when using S-meter squelch, problems with storage/recall of PL tone frequencies of 203.5 Hz. and/or 114.8 Hz., or problems with a lack of transmit on the UHF band modules during Remote operation can be corrected using the changes noted in this bulletin.

Notes:

1. All TM-642A transceivers work fine and do not require any changes.
   
   
2. TM-742/942's that exhibit any of these symptoms with serial numbers between 412XXXX and 509XXXX need only change IC1 on X53-3460-21 B/2.
   
   
3. TM-742/942's that exhibit any of these symptoms with serial numbers of 412XXXX and below must also change IC1 on X54-3130-11.
   
   
4. TM-742's with serial numbers of 509XXXX and greater have had these changes incorporated in production.
   
   
5. Some TM-742's and TM-942's below serial number 509XXXX were returned to Japan for modification. If the unit that you have has a black dot on the box near the serial number it has already been modified and requires no further action.
   
   

Parts Required:

Qty    Description    Old Part No.     New Part No.       Circuit Description
1      Microprocessor HD6433388A07F    HD6433388A22F      IC-1
                           or
                      HD6433388A14F                         
1      Microprocessor HD404719A26H     HD404719A32H       IC-1

Caution: This modification requires advanced surface mount soldering equipment that is rated for CMOS circuits. It also requires familiarity with advanced surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself.
Attemping to remove and replace either IC without the proper equipment and techniques can easiy damage the circuit boards and void your warranty.
Seek qualified assistance from your closest Kenwood Service Center (Long Beach, CA, or Virginia Beach, VA).

Time required for this moditication is 90 minutes or less.