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World of Ham Radio 1997
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==============================================================================
K E N W O O D
>>> A M A T E U R R A D I O S E R V I C E B U L L E T I N <<<
==============================================================================
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
==============================================================================
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