Kenwood SB-2016 Sevice Bulletin
IIP-KENWCOO
ELEC:TRONIC:S
INC:~
1
NATIONAL
SERVICE
DEPT.
SUBJECT:
DATE:
TO:
DC
August
All
Kenwood
Voltage
1,
1975
Authorized
Protection
Circuit
Service
for
Bulletin
(Same
Centers
KR-5400,
SB
2016
as
SB-059)
KR-4400,
and
KA-4006
production
A
voltage
The
numbers
protection
change
are
applies
06XXXX
KR-5400
KR-4400
KA-4006
(
NOTE:
THE
NEW
change
circuit
to
or
OLD
BOARDS
has
resulted
in
the
those
units
higher.
MAIN
AMP
X0?-1280-10
X0?-1280-11
X0?-1280-12
ARE
NOT
INTERCHANGEABLE
in
the
KR-5400, KR-4400,
of
the
above
UNIT
use
of
model
NEW
MAIN
X0?-1350-10
X0?-1350-11
X0?-1350-12
WITH
a
and
whose
AMP
THE
new
DC
KA-4006.
UNIT
OLD
serial
BOARDS.
and
The
a
basic
brief
circuit
description
layout
of
its
for
the
operation
new
is
2
protection
provided
circuit
below:
+B
(
"
KIENWOOO
11!5777
80UTH
BROADWAY.
GAROI!!:NA.
CALIFORNIA
Q0248
1)
Left
applied
2)
AC
do
not
3)
If
is
applied
Because
and
the
voltage
4)
If
appears
5)
R4
a
time
relay
6)
D3
of
Q2
power
channel
to
output
activate
a
positive
Ql
at
a
negative
at
and
delay
closes.
(Zener
and
allows
switch
point
signals
the
to
the
of
the
collector
"d"
also
"d"
through
C2
have
after
Diode)
a
is
turned
output
"a"
through
circuit.
DC
voltage
base
increased
voltage
decreases
DC
voltage
a
time
the
improves
quicker
signal
are
of
Dl
power
off.
(or
Rl
(or
bypassed
appears
Ql
(point
base
decreases.
and
appears
and
D2,
constant.
switch
the
release
R-Ch
output
R2).
via
Cl
at
"a",
"b")
voltage
Q2
is
turned
at
"a",
so
that
Therefore,
is
turned
switching
of
the
signal)
to
ground
this
through
Ql
is
As
a
result,
off.
this
Q2
is
on
characteristic
relay
and
voltage
R3.
turned
voltage
turned
there
until
when
the
is
the
is
on
off.
the
SB
2016
Additional
found
on
information
the
attached
including
sheet.
schematic
and
parts
list
are
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