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DISASSEMBLY
FOR REPAIR/BLOCK DIAGRAM
REPLACEMENT
OF ROTARY
SWITCH
WAFER
When
the
rotary
switch
is faulty,
replace the defective
wafer as follows.
@
@
©)
Pull out the rotary switch shaft.
Loose the hook fixing the wafer.
Pull out the defective wafer, after unsoldering its feet,
and replace it with a new one.
Hook
of rotary
switch
Rotary
switch
®
Shaft
=~
BLOCK
DIAGRAM
TUNER
SECTION
em
_RF_amp
Mixer
IFT
IF amp
LPF
Audio amp
FM muting
Selector |
|
|
Muting controller
P
Qg7~10
AM
BLOCK & LEVEL DIAGRAM/CIRCUIT
DESCRIPTION
VRi2
VRi3
$1:
SPEAKERS
VRg3:
VOLUME
Sg1:
SELECTOR
VRi1:
BALANCE
$g2-1:
LOUDNESS
VRi2:
TREBLE
Sg2-2:
TAPE
VRi3:
BASS
Sg2-3:
MONITOR
Sg2-4:
MODE
Sit:
TONE
DEFEAT
Si2:
SUBSONIC FILTER
@ 25.3V/82
frequency
= 1 kHz
OdB=1V
When the power switch is turned on, charging current flows
into Ce71 from +50 V. Since Oe22 does not turn on unless
Ce71
is completely charged and the base potential exceeds
1.2 volt, time constant of Ce71
and
Re74 is made to be
more than the time necessary for circuit stabilization.
Thus
shock noise cannot appear at the output circuit.
Since
Qe20
is forward-biased
to turn on after the power
switch has been turned off, Qe21 and Oe22 are turned off
to release
the
relay.
This depends
that —B
discharges
faster than +B does.
Signal line
OUTPUT
Qe21
& Qe22
(Darlington
connection)
ASO DETECTION
Qe11
(Qe12) is turned on when the overcurrent flows into
the power transistors.
Then, Qe17 turns on, Qe20 turns on,
Qe21
and Qe22 turn off, and the relay is released.
Power transformer
Dk7
This circuit operates for ASO detection,
DC detection and
power on-off shock noise prevention.
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