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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 # 1058
MODEL: TM-455A
SUBJECT: Change in Pin Diode

Symptom: Some early versions of the TM-455A/E have been discovered with a 
bad solder connection at the final module pin diode, D601. If the impedance 
of this device is too low, the power consumption for this device goes up. 
This increased power consumption might cause excessive heating of the solder
connections, and may result in a failure of the connection(s) after long 
FM transmissions.

Countermeasure: On the TX/RX Unit (X57-4510-00 C/5) replace the following:

Change Diode D601 to a UM9401, 
Change R606 to 100 ohms
Change C623 to 5 pF
Change C624 to 12 pf

After replacing these parts, readjust the NULL and Protection circuit using 
the procedures provided in the Service Manual.

Parts Required:

Quan. Description                 Part No.           Circuit Description

1     Pin diode                   UM9401             D601        
1     100 ohm chip resistor       RS14DB3A101J       R606
1     5 pF chip capacitor         CM73F2H050D        C623
1     6 pF chip capacitor         CM73F2H060D        C624


Time required for this modification is 60 minutes or less.
Service code A:34 B:X57-4510-XX C:D601 D:91