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                             K E N W O O D
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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 # 1006
MODEL: TS-850S
SUBJECT: Low/no Receiver Sensitivity

Symptom:

Reports of low or no receiver sensitivity accompanied by a lack of audio 
from the speaker during CW or SSB modes might be caused by improper RXB 
voltage levels.  Normal RXB voltage is +8 vdc during receive and 0 vdc 
during transmit. If you find approximately +2 vdc during receive you might 
suspect a problem with a leaking diode, D31 on the RF unit (X44-3120-00.)

Cause:  

D31 is used as the transmit switching diode. Leakage of this diode is most
probably caused by electrostatic surge or discharges from the antenna.  

Parts Required:

D31:.........................................MI204.

Procedure:
A temporary cure for units that have already been manufactured is to replace 
D31 with an MI204 diode.  Future production radios  will change D31 to an 
LFB01 diode and incorporate a change in the printed circuit foil pattern to 
allow addition of a series diode, D103 (LFB01).  

Caution: This modification requires soldering equipment rated for CMOS type
circuits. It also requires familiarity with surface mount soldering
techniques. If you do not have the proper equipment or knowledge do not
attempt this modification yourself.  Seek qualified assistance.

Time required for this modification is 30 minutes or less.
(E51-92-062)