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Technics SA-5170 - Block Diagram; Service Aid

Technics SA-5170
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=
BLOCK
DIAGRAM
TR301
AF
AMP
N01
STEREO
IND.
FM
rea
ee
1C101
1c102
a
TRI
fhe
Orion
ke
1
cF102
O—i9
1C30
FM-
RF
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FM-IF
[e|
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L__
ra[
Bee"
FM-IF
3
STEPS
AMP
am
6)
MD
aaquapraTureE
=
@——“HnN
®
DETECTOR
°
db
@—O-9
°
©
AF
AMP
TR302
“3°
(FM
MODE)
en
(LOUDNESS)
1¢401
ott,
z
-,
source
O
[PHONO
O
(DFGUALT
6)
.
ZER
AMP
tape?
wl
!
LEFT
O}
2
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>
=)
|
|
<<
I
La
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s
PHONO
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source
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PHONO
©
NCS
On
|
9
|
ta
RIGHT
AUX
pe
Ww
AUX
27
1
oye
ae
bee
|
REC
OUT
©
ong
LEFT
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we
ml
PLAYBACKC)
et
REC
OUT
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acl
REC/PLAY
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PLAYBACK
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=
SERVICE
AID
At
the
initial
stage
of
the
main
amplifier
of
this
unit,
the
differential
amplifier
of
current
mirror
load
is
employed.
This
is
a
circuit
for
obtaining
the
gain
higher
than
that
in
the
conventional
circuits,
with
current
in
the
differential
amplifier
stage
kept
constant.
when
Icl
is
increased
through
variation
of
base
voltage
of
the
differential
amplifier
TR1,
Ic2
at
TR2
is
reduced
with
consequent
decrease
in
the
voltage
drop
at
R2,
thus
resulting
in
rise
or
VBE
for
TR3
and
consequent
increase
of
Ic1.
As
the
characteristics
of
the
differential
amplifier,
|c2
is
reduced
as
!|c1
is
in-
creased.
In
this
way,
|c1
and
|c2
are
kept
constant
at
all
times
through
function-
ing
of
TRS.
Constant
current
means
that
high
impedance
is
connected
to
the
differential
amplifier
circuit,
and
thus
large
voltage
gain
can
be
obtained.
Another
cause
for
increasing
the
voltage
gain
is
the
push-pull
circuit
formed
by
TR1
and
TR3.
In
the
differential
amplifier,
signal
of
opposite
phase
is
obtained
at
the
collector
of
TR1
with
respect
to
the
input
signal,
while
in
the
collector
of
TR2,
signal
of
the
phase
as
the
input
is
obtained
to
be
further
applied
to
the
base
of
TR3.
Accordingly;
signal
of
opposite
phase
to
the
input
is
developed
at
the
collector
of
TR3,
thus
consequently
forming
the
push-pull
circuit
of
TR1
and
TR3.
In
other
words,
since
the.amount
of
NF
can
be
increased
with
the
rise
of
the
gain,
improvements
in
the
distortion
factor
and
S/N
ratio
can
be
achieved.
.
TR101
an
|
MUTING
|__.
HON
SWITCH
|
on
|
(MUTING)
°
|
°
i
(lees
ie
apeeea
|
202
(SPEAKERS)
Eh
oe
2.5A
Be
-
aE
A
EARPHONES
2.5A
=e
peel
4
Oo
REMOTE
yo
TONE
@VOLTAGE
INPUT
INPUT
OUTPUT
TR3
R2
R1
(CURRENT
MIRROR
CIRCUIT)
Fig.
1
SA-5170

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