Sony PS-X75 User manual

SPECIFICATIONS
GENERAL TURNTABLE
Power Requirements: 240 V ac ~ Platter:
adjustable, 50/60 Hz (UK model)
220 V ac ~ Motor:
adjustable, 50/60 Hz (AEP model)
120 V ac, 60 Hz (US, Canadian mode!) Drive System:
110 — 120, 220 — 240 V ac ~
adjustable, 50/60 Hz (E model)
Speed:
Power Consumption: 18W
Dimensions: Approx. 480 (w) x 165 (h) x 420 (d) mm
19 (w) x 61/, (h) x 16% (d) inches
including projecting parts and controls
Weight: Approx. 13 kg, 28 Ib 11 oz (net):
Approx. 15 kg, 33 Ib 2 oz
(in shipping carton)
SAFETY-RELATED COMPONENT WARNING!!
COMPONENTS IDENTIFIED BY SHADING AND MARK
A ON THE SCHEMATIC DIAGRAMS, EXPLODED
VIEWS AND IN. THE PARTS LIST ARE CRITICAL TO
SAFE OPERATION. REPLACE THESE COMPONENTS
WITH SONY PARTS WHOSE PART NUMBERS APPEAR
AS SHOWN IN THIS MANUAL OR IN SUPPLEMENTS
PUBLISHED BY SONY.
ATTENTION AU COMPOSANT AYANT RAPPORT
A LA SECURITE!
LES COMPOSANTS IDENTIFIES PAR UNE TRAME ET
UNE MARQUE /\ SUR LES DIAGRAMMES SCHE-
MATIQUES, LES VUES EXPLOSEES ET LA LISTE
DES PIECES SONT CRITIQUES POUR LA SECURITE
DE FONCTIONNEMENT. NE REMPLACER CES
COMPOSANTS QUE PAR DES PIECES SONY DONT
LES NUMEROS SONT DONNES DANS CE MANUEL
OU DANS LES SUPPLEMENTS PUBLIES PAR SONY.
US Model
Canadian Model
AEP Model
UK Model
E Model
STEREO TURNTABLE SYSTEM
Speed Control Range:
Starting
Characteristics:
Wow and Flutter:
Signal-to-Noise Ratio:
Speed Deviation:
Load Characteristics:
Automatic System:
32 cm (125/, inches), aluminum-alloy diecast
DC servo-controlled linear BSL motor
Direct drive, crystal-lock and magneciisc servo
control system
331/, rpm, 45 rpm
+10 % (crystal! lock OFF)
Comes to nominal speed within a habf
revolution (331/, rpm)
+0.035 % (DIN)
0.025 % (WRMS)
78 dB (DIN-B)
Within 0.003 %
0
%
at
tracking
force
up
to
150
g
(at
lead-in
groove
of
a
record)
Lead-in, return, reject, repeat
record-size selection
— Continued on page 2 —
SONY.
SERVICE MANUAL

PS-X75 |
TONEARM
Type:
Pivot-to-Stylus Length:
Overal! Arm Length:
Overhang:
Tracking Error:
Stylus Force
Adjustment Range:
Sheil Weight:
Cartridge Weight
Range:
(including supplied
headshe!l)
Electronic tonearm, universal
235 mm (91/, inches)
330 mm (13 inches)
13 mm (%,6 inches)
+2°40', —1°30'"
0-—3.09
11g
12-199
19 — 26 g (with extra weight)
MODEL IDENTIFICATION
— Specification Label —
STEREO TURNTABLE SYSTEM
MODEL NO, PS-X75
SERIAL NO.
US, Canadian model:
AC 120 V 60 Hz 18 W
AEP model:
AC 220 V ~ 50/60 Hz 18 W
MADE IN JAPAN
UK model:
AC 240 V ~ 50/60 Hz 18 W
E model:
AC 110 — 120, 220 — 240 V ~ 50/60 Hz 18 W

| PS-X75
SERVICING NOTES
Handling
Precautions
for
MOS
ICs
(1C103,
104,
107,
108,
110
—
112)
Generally, the insulation resistance of the oxide
layer in. MOS IC structures is very high, and the oxide
layer is very thin. Because of this, it is possible that
the static voltages usually present on clothes and the
human body will be enough to generate a potential
difference across the insulator, high enough to cause
a breakdown of the insulating layer.
The following precautions should be taken while
handling these ICs.
(Particular care should be taken under conditions
of low humidity.)
Precautions in Replacing MOS ICs
1.
Store
new
ICs
by
inserting
them
into
a
urethane-
polyester
cushion
(which
is
somewhat
conduc-
tive),
or
wrapping
it
in
aluminum
foil,
so
that
all
the
pins
are
at
the
same
potential.
(The ICs should be stored in that manner until
mounted on the circuit board.)
Fig. A
partially conductive
unrethane-polyester
cushion
1c
Fig. B aluminum foil
2.
Check
the
soldering
iron
for
possible
power-line
leakage
current.
Make
sure
that
there
is
no
leakage
path
by
connecting
an
ohmmeter
to
the
tip
of
the
soldering
iron
and
the
plug
as
shown
in
Fig.
C.
If
there
is
a
leakage
path,
use
some
other
soldering
iron.
VOM
(2.x 10,000 range)
3. Equalize any potential difference between the
clothes, the tools in use, the work bench, the
set being worked on, and the packaged IC by
touching them all in succession with the hands
or a conductive wire or tool.
4.
The
following
are
effective
methods
for
handl-
ing
ICs
that
remove
the
potential
difference
across
the
oxide
layer.
@ Use a paper clip modified by soldering in a
wire braid insert.
wire braid
soldered soldered
: Make sure that there is
Fig. D no solder on the inside.
clip
partially conductive
" urethane-polyester
Fig. E cushion or aluminun
oil
wire braid
D>)
clip
(—=—~sossscsnssecsereor es
aes @aSabeas
ITT Lt Ld hae
SXXEE AEE EES
Make sure that all the pins are in
contact with the wire braid {all
: the pins will then be at the same
Fig. F _ potential.).

PS-X75
® Take a short length of fine bare wire and
wind it around the IC so that it shorts all the
pins of the IC, while it is still in the urethane-
polyester cushion or aluminum foil. This
ensures that all the pins are at the same
potential.
fine bare wire
(stripped solid hookup
wire, etc.)
partially conductive
urethane-polyester
cushion or aluminum
foil
Fig. G
@ When it is necessary to handle the IC with
the fingers, do not touch any pin, and hold
the IC at the ends of its plastic-package case
as shown in Fig. H.
Fig. H
Method of Mounting
Insert the IC while holding it with the modified
clip, and solder all the pins with the clip still
shorting the pins. (Similarly, solder all the pins
while the bare shorting wire is still wound
around them.). Remove the clip or the bare
shorting wire only after all the pins have been
soldered.
Precaution while Checking C-MOS ICs
The C-MOS ICs (Complementary MOS) are MOS
ICs that have their output sections made up of
N-channel and P-channel push-pull stages to increase
their speed of operation. If the output terminal of
these ICs comes into contact with B+ or B- voltage,
then the FET which is ON at that time will either
become shorted or open.
This is valid for all the output sections that are
connected together by the interconnections. Even
the circuits that are physically separated (and not on
the same board) can be destroyed simultaneously.
Example:
If this line is grounded, or touches
B+ or B- bus..., the output stage
of this IC will be destroyed.
Fig. 1

PS-X75
SECTION 1
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PS-X75 |
1-2.” ELECTRONICALLY-CONTROLLED
TONEARM “BIOTRACER”
1-2-1.Resonance Damping at Low Frequencies by
Speed Feedback:
Tonearm vibration, particularly the resonance
generated at low frequencies, is automatically reduced
by feeding the speed fractuation to the linear motor
which monitors the speed of the tonearm.
1-2-2. Front-panel-controlled Stylus Force:
To set the stylus force, turn the knob on the front
panel, and the built-in microcomputer will measure
the force. Changing of the stylus force while listening
to the tones is also possible.
1-2-3. Remote Full-Auto Function:
A luminar sensor controls the tonearm’s lead-in
and return, while monitoring of the down and return-
ing positions is carried out by the linear motor.
Accordingly, the operation is accurate and virtually
silent.
1-2-4. Tonearm Lifter Control from Front Panel:
The up/down operation of the tonearm lifter is
controlled by the vertical linear motor, and the
damper, fitted with a speed feedback circuit, operates
smoothly free from the effects of temperature
change and aging. A muting circuit operates when
the tonearm is in its top position and because this
function is cancelled when the tonearm is down
on the turntable, the bother of having to lower the
amplifier volume every time the stylus has landed
on the record is eliminated.
1-2-5, Fast Repeat Facility:
Repeat operation, controlled electronically by
the horizontal linear motor, begins as soon as the
tonearm returns to near the edge of a record.
1-2-6. Manual Operation with the Dust Cover in Place:
Manual operation is throughly possible without
touching the tonearm, since the upward/downward
and rightward/leftward movement of the tonearm
can be done by buttons provided on the control
panel.
1-3, TURNTABLE AND OTHERS
1-3-1. Automatic Record-size Detection Facility:
The size of records is monitored and measured
by using a photo-electric device and a built-in micro-
computer which then automatically puts the tonearm
into operation.
1-3-2. Crystal-locked Magnedisc Servo System:
The turntable driving system employs the es-
tablished magnedisc system known as a highly-
accurate rotation monitoring and, a phase-locking
using a precision output frequency generated by
a crystal oscillator to obtain a constant turntable
rotation with low drift.
1-3-3. Linear BSL Motor:
A smooth and silent rotation is obtained from
the Linear BSL Motor — almost no cogging which
can become a source of wow and flutter or S/N
degradation. Having a high torqueage, the starting
response is excellent at a half of a turn.
1-3-4, Turntable Incorporates Electromagnetic Brake:
Playing of records is easy due to the tonearm’s
independent operation and the simple start/stop
Operation of the turntable rotation, and a lead-in
to a music is done very easily. Also, with the electro-
magnetic brake, stopping the turntable is smooth
and quick as well as simple to use.

1-4, CIRCUIT DESCRIPTION
1-4-1. When the POWER Switch is turned on (see Fig. 1):
The waveform shaper, consisting of IC111, turns
the voltage at terminal (3) of IC102 to low level
“0” in half a second during which C112 is charged
with B+ power. Asa result, IC102 is reset.
OV
Fig. 1 S501 (POWER}: ON
1-4-2. Arm Lifter Raising/Lowering Circuit(see Fig. 2):
Turning the power switch on raises the arm lifter.
[Lowering the arm lifter]
When S508 (UP/DOWN) is depressed, the voltage
at
terminal
(24)
of
IC102
becomes
high
“1”.
This
turns the voltage at terminal (6) of IC112 to positive
and
the
voltage
at
terminal
(7)
to
negative.
Asa
result, Q131 switches on.
The
potential
of
the
terminal
(2)
of
IC112
now
becomes
negative
and
the
output
of
the
terminal
(1)
goes
positive.
This
turns
Q128
on.
| aa
OV
ARM LIFTER
DOWN
Fig. 2
-—-7-—
| PS-X75
This means that the microprocessor (IC102)
does not operate for 0.5 seconds after the power
switch is turned on.
Also, buttons can be effectively pressed after
it is assured that the tonearm has been on the arm
rest for about 0.5 seconds.
S501 (POWER): ON
rn IT
Since both Q128 and Q131 are on, current passes
through L505 (lifter drive coil) in direction A, thus
lowéring the arm lifter.
[Raising the arm lifter]
When S508 is depressed, the voltage at terminal
(25) of 1C102 becomes high “1”. This turns the
voltage at terminal (7) of IC112 to positive, switching
Q130 on.
Since Q130 is on, a negative voltage appears at
terminal (1), turning Q127 on. Now that both Q127
and Q130 are on, current passes through L505 in
direction B, thus raising the arm lifter.
ARM LIFTER ARMLIFTER
DOWN
ARM LIFTER ARMLIFTER
DOWN uP

PS-X75 |
1-4-3.
Tonearm
Swivelling
Circuit
(see
Fig.
3):
Turning the power switch on returns the tonearm
to the arm rest.
[ > : BACK]
When S507 ( > : BACK) is turned on, the voltages
at terminals (17) and (18) of IC102 become high “1”.
This turns the voltages at terminals (6) and (7) of
IC110 respectively to positive and negative. <A
negative voltage then appears at terminal (1) of
IC110.
FORWARD
1-4-4, Tonearm Lifting Circuit (see Fig. 4):
When the arm lifter is lowered in the zero balance
are, Q108 turns off because the voltage at terminal
(20) of IC102 is high “1”. As a result, varying
RV502 (STYLUS FORCE:ANTI SKATING) causes
no change in the stylus force.
However, since the voltage at terminal (23) of
IC102 becomes low “0”, a positive voltage appears
at terminal (1) of I1C109, turning Q121 on. This
causes current to pass through L501 (vertical drive
coil) in direction A and lifts the tonearm. This
function helps apply a constant stylus force when
the tonearm is moved forward or backward, thereby
preventing the arm from deflecting.
Also, since the voltage at terminal (26) of 1C102
becomes low “0”, Q133 turns off. This lowers the
gate voltage of Q132, resulting in no MFB current
which would otherwise generate in L502, with the
movement of the tonearm. When the arm lifter is
Fig. 3
As
a
result,
Q125
turns
on
to
pass
current
through
L503
(horizontal
drive
coil)
in
direction
A,
returning
home
the
tonearm.
[<d: FORWARD]
When S506 (<: FORWARD) is turned on, the
voltages at terminals (15) and (16) of IC102 become
high “1”, This turns the voltage at terminal (1) of
IC110 to positive, and, consequently, switches Q124
on.
Now that Q124 is on, current flows through L503
in direction B, moving forward the tonearm.
lowered outside the zero balance area, Q108 turns
on because the voltage at terminal (20) of IC102
becomes low “0”. Asa result, varying RV502 causes
voltage ranging from 0 to 5 volts to be applied to
terminal (6) of IC109. A negative voltage then
appears at terminal (1), turning Q122 on.
Now that Q122 is on, L501 has current pro-
portional to the stylus force in direction B.

5V
ov
ie]
ARM LIFTER DOWN
| PS-X75
Bt
= Q108
UT OF ZERO BALANCE.
ST @
0 1) STYLUS FORCE
Og7>39
ae Tepe at avaoe
TO
HORIZONTAL-
[-D
9
DRIVE CIRCUIT FSO =
Bt
1C109 er
ce oO”
sas @-O-}>-O+Omn | |S
aie ote a.
Mma bd
2] & 1502
iaioe al Com &
7 B
STYLUS FORCE 2 9 Q122
NE
39 Bt <I
0133
eae er
BALA @ ©) Le 6) tO) i> Q132
5 Vv \ ci _
1C102 oie 1C103
kay
WITHIN ZERO ; B-
BALANCE Fig. 4
(ARM LIFTER DOWN)
1-4-5, Automatic Disk Size Detector (see Fig. 5):
As long as the turntable is rotating, the light from
PLS501 passes through the prism on the turntable
mat and switches phototransistors Q501 and Q502.
The outputs of Q501 and Q502 are fed to termi-
nals (30) and (31) of IC102 to be used for automatic
detection of the disk size.
when no record
placed —--~
SS
when a record p+
placed: OV
when no record ___
placed i [| |
OV
when a record placed: 0V
[Nodsk | 1 | St *d Cn
Ee ee ee ee ee e when a record plaed: 0
when no record paced: 7
Q502
PL501 Le
B-
Fig. 5

PS-X75
1-4-6. Drop-point and End Detection (see Figs. 6 and
7):
When S504 (AUTO START) is turned on, the
tonearm moves toward the disk.
The presence of a drop-point on the disk is deter-
mined by counting slits of the movable shutter ro-
tating with the tonearm.
The end of a disk is also detected by counting
slits of the movable shutter. After detecting the end,
the tonearm returns.
Slits are counted as follows. The light emitted
by D401 and D402 strike on the movable shutter.
If the light from D401 (D402) passes a slit, it turns
on Q301 (Q302). The outputs of Q301 and Q302
are fed to the Schmitt circuit consisting of IC103,
where the waveforms are shaped. The shaped outputs
are applied to terminals (32) and (33) of IC102.
Also, whether the tonearm is moving forward
or backward is determined by comparing the phases
of the signals from terminals (32) and (33) of IC102.
fixed slitA — —_
phase difference: 90°
slit of movable
shutter
—_— = fixed slitB
slit B | | | | | | | | | |
{FORWARD)
slitA | | | | | | | | | |
slitB | | | | | | | | | | |
(BACK)
D401
D402
Fig. 7