Pioneer TX-608 - System Block Diagram; Circuit Descriptions; AM Tuner Circuitry

TX-GS00
3.
BLOCK
DIAGRAM
ae
Lc
RF
Lc
tF
ae
DEMODULATOR
@)
MIXER
SCOR
ee
tt
esate
@®® Of
hive
:
CERAMIC
FILTER
a
H
AMO— |
ea
rae
LC
|LOCAL
DE-EMPHASIS
! TUNE| OSC.
SIGNAL TUNING
} rene TUNING (STEREO/MONO) &) 75/25us
‘@
Fs
Lo]
STEREO
H
ee
/ BAR-
/ ANT.
i
--——-JLC
TUNE
fe
@
B
TRANSFORMER
vi
!
abl
FUNCTION
RECTI~
oy,
V.R. Ord OS)
f
n
(AM
OSC)
CONTROL
FIER
ae
ti
ov
/
‘@
‘@
DQ
ILLUMINATION
Qe
eee
ke
FM
AM
OS)
FUNCTION
(6)
(©)
(C)
LAMPS
HNVULEYUOUAUUVTQQUDUANIQUEDLUUOUUCUQUDULTUUUUTVOCUALLSTHUOOUTTUUUEOOEUCOOU
QUAN
UL
UTOOEUUPEG
TAO
EAOT
VCORE
4.
CIRCUIT
DESCRIPTIONS
4.1 AM TUNER
The
AM
tuner
employs
a
2-ganged
tuning
capaci-
tor,
a
single-element
ceramic
filter,
and
an
IC
(HA1138)
consisting
of
an
RF
amplifier,
mixer,
2-stage
IF
amplifier,
detector
and
AGC
amplifier.
See
Fig.
4-1
for
the
block
diagram.
When
the
FUNCTION
switch
(S3)
is
in
the
FM
position,
+B
is
applied
to
the
emitter
of
Qi:
via
Rs2,
Re2
and
Res.
Qii
will
turn
off,
and
the
local
oscillator
circuit
will
be
opened.
Fig. 4-1 AM tuner