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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 # 856
MODEL: TS-660
SUBJECT: Microprocessor Latchup

Microprocessor latchup may occur if the power switch is cycled several 
times in quick succession, if the supply is turned off while the power 
switch remains on, or if the power supply is turned on with the transceiver 
already on. Symptom will be no display, erroneous display, or locked 
display. Change two components on the Control unit to prevent further 
trouble.

On the Control unit X53-1220-00:

1. Replace R23 680 ohm with a 470 ohm resistor (RD14CB2E471J).

2. Remove and delete C4 47pF

3. Add a 22pF 16v electrolytic (CE04WlC220M) on the foil side of the 
board between D24, R23 (positive) and ground (negative).



Notes: 1. This change applies to units before serial number 209xxxx.

2. Installation time for this procedure is 1/2 hour or less.