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World of Ham Radio 1997
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WOHR97_AmSoft_(1997-02-01).iso
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asb1050.txt
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1997-02-01
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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 # 1050
MODEL: TS-950SDX
SUBJECT: Sub Band Residual Noise
Symptom: The level of residual noise (AF VOL at Min) on the SUB band is
slightly higher than that of the MAIN band. This is especially true at
audio frequencies of around 50 Hz, as viewed on a spectrum analyzer.
As a result the SUB receiver is more susceptable to motor noise, such as
might be generated by fans, refrigirators, etc.
Countermeasures: Replacing the Control Unit electrolytic capacitors
(C33, C34, and C39) with Tantalum capacitors, and adding the bypass
capacitor to the Switch unit reduces or eliminates this symptom.
Parts Required:
Qty Description Kenwood Part No. Circuit Description
1 0.1 uF 35vTantalum cap C92-0001-05 C33
1 1.0 uF 16v Tantalum cap C92-0004-05 C34
1 10 uF 16v Tantalum cap C92-0505-05 C39
1 .01 uF disc capacitor CK45B1H103Z NA
Procedure:
Replace C33,C34,C39 with the new capacitors listed above. The components
will be located on the Control Unit (X53-3380-00) foil side.
On Switch Unit (X41-3250-00 B/10) cut the trace from one end of VR2 and
add the .01 disk across the cut. The proper trace is the longest one.
Cut and Add Cap.
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End Cent End
VR2
Caution: This modification requires advanced surface mount soldering
equipment that is rated for CMOS circuits. It also requires familiarity
with advanced surface mount soldering techniques. If you do not have the
proper equipment or knowledge do not attempt this modification yourself.
Seek qualified assistance from your closest Kenwood Service Center
(Lonq Beach, CA, or Virginia Beach, VA).
Time required for this modification is 60 minutes or less.
Service code A:09 B:X53-3380-00 C:C33, 34, 39 D:91