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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 # 977
MODEL: TM-731A/TM-631A
SUBJECT: 2MTR FINAL UNIT FAILURE
We have seen several 144MHz Final boards in for service that have an
RF burn in the area of L6 and C17. The combination of transmit current
on the 8T line and SWR seems to be damaging C17. Once C17 is damaged,
the circuit starts to burn. To prevent this condition, C17 will be replaced.
This modification has been incorporated in production from serial
number 108XXXXX.
REQUIRED PART: CK41FY1E102M
1. Disconnect the power supply and antenna.
2. Remove the top cover. Do not damage the speaker wires.
3. Remove the shield plate from the VHF Final unit.
4. Replaced C17 with the part listed above.
If you are servicing a TM-731A/631A that has already been damaged, the
following items should be noted.
1. R11 is probably burned and needs to be replaced.
2. L6 may have "pin hole" burn marks through its insulation. If this is
the situation, L6 must be replaced or the circuit will burn in the future.
3. If the board has been burned, the carbon must be scraped off the board
to prevent the circuit from burning any further.
Time required to perform this modification is 1 hr. or less.