Kenwood KT 4133 Service Manual

Page 2

CONTENTS

EXTERNAL VIEW ................................ 3
INTERNAL VIEW ................................ 4
BLOCK DIAGRAM ............................... 4
DISASSEMBLY FOR REPAIR ........................ 5
DIAL CORD STRINGING ........................... 5
CIRCUIT DESCRIPTION ........................... 6
EXPLODED VIEw ................................ 12
EXPLODED VIEW PARTS LIST ....................... 13
PARTS LIST .................................... 14
ADJUSTMENT

ADJUSTMENT ............................... 17

R'EGLAGES ................................. 21

ABGLEICH ................................. 25
SEMICONDUCTOR SUBSTITUTIONS ................... 23
PC BOARD ..................................... 28
SCHEMATIc DIAGRAM ............................ 31
SPECIFICATIONS ................................ 31
ALTERNATE SCHEMATIC DIAGRAMS ................. 32

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Page 11

CIRCUIT DESCRIPTION

5.4 017

Since 81 is a short type switch, its both ends are shorted,
and 017 is energized when FM is changed over to AM or
vice versa, In this case, the base of 016 is connected to
the ground via 05, thus deenergizing 016. The collector
016 goes high to stop the motor, and simultaneously de-
energizes 010, and 02 and Q3,

6. SUB UNIT OPERATION

This circuit uses the muting (Pin 12) function of 1C2 HA-
1137W at FM low.

:2 Rl70 5.6k

l0.7MHz

12
_\
LPF D54
CELCBZ. R169
06
f DC voltage
H I 1C2 output
I
|
0- I ----> Frequency
} IO.7MHz
I
|
H : Collector of as
I
O ___ : ______ Frequency
|
I

Fig. 9

07 is energized when the tuner is accurately tuned in, and
is normally controlled by the noise amplifier output (the
collector of 06). At FM low, an OR of the output from
Pin 12 of |C2 and the collector output of O6 is generated
so that the range wherein 07 is energized is widened. In
other words, smooth tuning in is made possible even at low
input level by narrowing the positive tuning range.

At FM high, the output from Pin 12 of lC2 is grounded
via D52 so that no further operation takes place. The sub
unit operation is approximately as follows. If the tuner
gets within the band zone of the noise amplifier while
selecting an FM station (when the collector of 06 is low),
a trigger input is sent to the base of 024 via C84 and D56.
024 is energized, and its collector goes low so that the
output from Pin 12 of lC2 is grounded via D55 and thus
no longer affects the operation. The moment the station
is tuned in to, Pin 8 of |C4 goes high, energizing 023 via
R172, which deenergizes 024 and cuts off D55. This condi-
tion is kept by R173.

Selection of a separate station can be made with smooth-
ness because the output from Pin 12 of 1C2 is already
disconnected from the ground and applied to the base of
O7, and the range of accurate tuning point is narrowed.
In AM, the output from Pin 12 of ICZ is grounded via D53.

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