Sony HP-210 - Circuit Analysis; Record-Changer

~~Record changer: --"-~
Phonograph Section
BSR -C-116, ~four~-speeds—
(1673,
3331/3,
45,
78
rpm)
Cartridge: SONY Crystal Cartridge
VX-18P
Stylus: SONY Diamond Stylus
ND-120P
Number of records
played automati-
cally: Up to 5 LP records
Speaker Section (SS-210)
System: 2-way (61/." (16 cm) woofer,
2” (5 cm) tweeter)
Impedance: | 8 ohms
Dimensions: 91/," (width) x 15” (height)
x 83/3" (depth)
235 mm (width) x 380 mm
(height) x 213 mm (depth)
Net weight: 6lb 10 0z (3.0 kg)
Shipping weight: 18 Ib 120z (8.5 kg) per
pair in shipping carton
General
50 watts
x 75 watts
120V ac
x 100, 120, 220, 240V
50/9 Hz ac
Power consumption:
Power requirements:
Dimensions:
x 161/g" (depth)
421 mm (width) x 241 mm
(height) x 410 mm (depth)
241b 80z(11.1kg)
30lb 1402 (14kg)
Net weight:
Shipping weight:
%* : General Export Model only
1-2. CIRCUIT ANALYSIS
The following describes the functions of all
stages and controls. The text sequence follows
signal paths. Stages are listed by transistor reference
designation at the left margin; major components
are
also
listed
in
a
similar
manner.
Refer
to
the
block
diagram on page 7 and the schematic diagrams on
pages 40 to 43.
16%16" (width) x 91/2" (height)
Stage/Control
“Fm Front-End ~
Balun Bi01
Rf amplifier
Q101
Local
oscillator
Q103
AFC circuit
D101, D102
C115, C119,
R113, R114,
RIS
Function
This transformer matches 300-
ohm twin lead to the fm front-
end’s input stage.
The rf amplifier and tuned cir-
cuits. provide high sensitivity,
good image rejection, and good
selectivity. Field-effect transistor
Q101 is ideally suited for this
job since it has low-noise charac-
teristics and a wide dynamic
range. The latter characteristic
results in very low-cross modula-
tion products. Antenna coil
L101 is tapped to match the
low-input impedance of the
common gate amplifier.
This oscillator supplies injection
voltage to the mixer via oscil-
lator coil L103. The circuit is a
modified Hartley oscillator with
feedback applied to the emitter
from a tap on tank coil L103.
An automatic frequency control
circuit is incorporated in the
oscillator to provide easy recep-
tion of fm signals. Tuning is
usually performed by ear, that
is, turning the tuning knob and
setting it to the position where
the clearest sound is heard. How-
ever this is rather difficult job.
By using afc, the difficulty of
tuning and frequency drift in the
local oscillator can be elimi-
nated.
The principle of afc operation is
as follows:
When the tuner is correctly
tuned, the intermediate fre-
quency is kept 10.7 MHz and no
dc correction voltage is produced
by the ratio detector as shown
in the ‘“S” curve response
Fig. 1-1. So, the voltage applied
to diode D101 is determined
solely by the positive fixed -
reverse bias voltage supplied by
zener diode D102.
Now assume that the local oscil-