Sony PS-2250 User manual

General
Speeds:
Turntable drive:
Wow and flutter:
(weighted)
Signal-to-noise ratio:
(weighted)
Motor:
Turntable platter:
Start-up-time:
rower consumption:
Power requirements:
Dimensions:
PS-2250
TTS-2250
SPECIFICATIONS
33-/3, 45 rpm +4 %, adjustable
Direct drive system
Less than 0.07 % (DIN 45507)
Less than 0.04 % (WRMS)
Greater than 58 dB (JIS)
Greater than 67 dB (DIN 45544)
AC servo-controfied motor
310 mm (12-/16") dia, 1.5 kg
(3 Ib 5 oz) diecasted aluminium
Less than 2.5 seconds
15 watts
110, 127, 220 and 240 V ac,
50/60 Hz
490 mm (width) x 185 mm
“(height) x 395 mm (depth)
19-7/39"" (width) x 77/32"
(height) x 15-1 4/32" (depth)
328 mm (width) x 146 mm
(height) x 357 mm (depth)
12-2°/39"" (width) x 5-3/4”
(height) x 14-1/; 6” (depth)
Net weight:
Shipping weight:
Tonearm (PUA-114)
Type:
Arm length:
(Pivot-To-Stylus)
Over hang:
Stylus force adjustment
range:
Anti-skating force
compensation range:
Tonearm height
precise adjustment range:
Cartridge weight range:
Shelf-head weight:
11.3 kg (24 Ib 15 oz), PS-2250
7.5 kg (16 ib 9 oz), TTS-2250
14 kg (30 Ib 14 02), PS-2250
10 kg (22 Ib), TTS-2250
Static balanced
245 mm (9-7"/32"")
9,
14mm (/16 )
0 to 3g. 0.1 g increments
0 to 3g. 0.5 g increments
4.65 cm ~ 5.15 cm
(1-° 7/32") ~(2-Y/32")
4gtoilg
CW-50 (optional counterweight)
10g~17g
10.59
~
SERVICE
MANUAL

TABLE OF CONTENTS
Section Title Page
1. TECHNICAL DESCRIPTION
“4-1. Technical Specifications 2... ee ee ee 1
1-2. Principle of ac Servo System... 2... ee ee eee 1
1-3. Block Diagram «ww ee ee 4
2. DISASSEMBLY AND REPLACEMENT
2-1. Top Cover Removal ...........6. rid aia Hee TOA: ee a) Ae CO a 5
2-2. Bottom Plate Removal .. 2. 1. 1. et 5
2-3. Turntable Base Removal ... 2... 1. ee ee ee ts 5
2-4. Servo Amplifier Chassis Removal... 2... 1 eee ee ee eee 6
2-5. Servo Amplifier Cover Removal . 2... 2... eee ee es 6
2-6. Power Supply Chassis Removal .... 2.2... ee ee eee eee 6
2-7. Motor Replacement .. 1... 6. ee ee ee ee 6
2-8.
Microswitch
Replacement
......
2.2...
ee
ee
erase
eatin
ven
a
7
2-9. Strobe Lamp Replacement... 1... ee ee ee ee ee 8
2-10. Power Transistor Replacement... 1... ee ee et ee eee ee 8
2-11. Tonearm Assembly Removal... 0... eee ee 8
2-12. Tonearm Base Removal .. 1... 1. 1 eee ee et ee ee eee 8
2-13. Tonearm Lifter Replacement... 2... ee eee ee ee ee ee 9
2-14, Bias Cord Stringing... 2.0. 2 ee ee eee iesleet Stet 9
3. ADJUSTMENT PROCEDURES
3-1. Speed Adjustment 2.2... 1 es 10
3-2. Tonearm Height Adjustment... 2... ee eee ee ee es 10
3-3. Stylus-Force and Anti-Skating Force Adjustment ..........-. 10
3-4.
Lateral
Balance
Adjustment
..
2... 2...
ee
ee
ee
ee
ee
11
3-5. Lubrication 2... 0. 1 ee ee ee ee ee ee es 11
4. DIAGRAMS
4-1. Wiring/Mounting Diagram - AEP Model— .........--.-.4--. 13
4-2. Wiring/Mounting Diagram — EP Model— ...... 2.2.22 ee eee 15
4-3. Schematic Diagram .. 2... 1. ee ee 17
4-4. Mounting Diagram .. 1 2. 1 ee ee ee 19
5,
-
EXPLODED
VIEWS
203s.
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6.
REPAGKING:
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7.
ELECTRICAL
PARTS
LIST
......-...
2.02252
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26

SECTION 1
TECHNICAL DESCRIPTION
1-1. TECHNICAL SPECIFICATIONS
Technical specifications for PS-2250/TTS-2250
are listed in TABLE 1.
Note: TTS-2250 is a turntable unit only.
TABLE 1. TECHNICAL SPECIFICATIONS
Speeds:
Turntable drive:
Wow and flutter:
(weighted)
Signal-to-noise
ratio:
(weighted)
Motor:
Turntable platter:
Start-up-time:
Power
consumption:
Power
requirements:
Dimensions:
PS-2250
TTS-2250
Net weight:
Shipping weight: .
General
33-1/3, 45 rpm +4 %, adjustable
Direct drive system
Less than 0.07 % (DIN 45507)
Less than 0.04 % (WRMS)
Greater than 58 dB (JIS)
Greater than 67 dB (DIN 45544)
AC servo-controlled motor
310 mm (12-3/16') dia, 1.5 kg
(3 lb 5 oz) diecasted aluminium
Less than 2.5 seconds
15 watts
110, 127, 220 and 240 V ac,
(GEP Model) 50/60 Hz
100, 120, 220 and 240 V ac,
(General Export Model) 50/60 Hz
490 mm (width) x 185 mm
(height) x 395 mm (depth)
19-9/32" (width) x 7-9/32”
(height) x 15-11/32” (depth)
328 mm (width) x 146 mm
(height) x 357 mm (depth)
12-29/32" (width) x 5-3/4"
(height) x 14-1/16 (depth)
11.3 kg (24 lb 15 oz), PS-2250
7.5 kg (16 lb 9 oz), TTS-2250
14 kg (30 lb 14 02), PS-2250
10 kg (22 Ib), TTS-2250
Tonearm (PUA-114)
Type:
Arm length:
(Pivot-To-Stylus)
Over hang:
Static balanced
245 mm (9-21/32")
14 mm (9/16')
Stylus force
adjustment range: Oto 3g. 0.1 g increments
Anti-skating force
compensation
range: Oto3g. 0.5 g increments
Tonearm height
precise adjustment
range: 4.65cm ~ 5.15 cm
(1-27/32") ~ (2-1/32")
Cartridge weight
range: 4gtollg
CW-50 (optional counterweight)
10g ~17¢g
Shell-head weight: 10.5 g
1-2. PRINCIPLE OF AC SERVO SYSTEM
Fig. 1-1 shows a simplified diagram of the ac
servo system employed in this set. Since the ac motor
speed is proportional to the applied ac voltage,
it is controlled by varying the applied voltage (Em) to
the motor. This is effectively performed by means of
series resistor Rv.
In practice, series resistor Rv is replaced by the
diode-bridge circuit and collector-emitter impedance
of a power transistor as illustrated in Fig. 1-2.
Note that the diode-bridge determines only the
direction of the ac current which flows in the power
transistor.
Motor speed is converted into ac signal by
means of a direct-coupled frequency generator. The
servo amplifier compares this signal against a very
stable dc reference voltage, and then controls the
collector-emitter impedance of power transistor. Any
error.in motor speed results in a correction. voltage
supplied to the motor.
SERVO AMP
Fig. 1-1. Principle of ac servo system

SERVO AMP
Fig. 1-2. Practical ac servo system
Stage/Control Function
Start Operation
When the power switch is turned on,
Q06 in the base circuit of QO7 is cutoff.
As a result, C8 in. the collector circuit
is charged through R27,R8, VR2, R10,
VRI and R9 when the 33 rpm button
is depressed. Note that VR2 and R10
is shorted during 45 rpm operation.
Q07 is forced into conduction when
C8 is charged up to some specified
voltage. As a result the following
conditions exist: :
Q09 QO10 QOlI Q3 Q4 Q5 Q6
OFF OFF ON ON ON ON ON
and a large enough ac voltage is applied
to the motor so the motor starts to
revolve rapidly.
Correct Speed Condition
Frequency
generator When the motor starts to revolve, the
frequency generator (F.G.) generates
ac voltage whose frequency is pro-
portional to the motor speed. As the
frequency generator is directly coupled
to the shaft of the drive motor, it
converts motor speed into frequency.
Differential Q1 and Q2 forma differential amplifier
amplifier which amplifies the input FG signal to
the level required for the following
Ql, Q2
limiter circuit.
Note that the output is extracted from
collector circuit of Ql] and Q2, and
then fed to the flip-flop stage through
diode limiter D1 and D2.
Stage/Control Function
Diode limiter Removes all amplitude variations from
D1, D2 the signal. Each diode conducts when
the signal across it exceeds the barrier
potential (0.6 V) in a forward biased
condition. Thus, the output signal is
limited to about 1.2 V peak-to-peak.
Flip-flop Q01 and QO02 form a flip-flop circuit
circuit which generates square output in ac-
Q01, Q02 cordance with the input trigger signal
(limiter’s output).
The flip-flop output is extracted at
collector circuit of QO2 and then fed to
the buffer amplifier stages.
Buffer/phase Q0O3, Q04 and QOS form a buffer
inverter amplifier stage. Note that Q03 and
Q03, Q04, Q05 are emitter followers but, Q04
Q05 acts as a phase inverter.
Differentiation Square wave output at the emitter
circuit circuit of QO5 is converted into spike
C7, RO12 pulses through the differentiator circuit
(formed by C7 and RO12) to trigger
the following saw-tooth wave generator
(Q06).
Saw-tooth Q06 and RC components (C8, R9,
wave VR1, R10, VR2) in the collector circuit
generator form a saw-tooth wave generator.
Q06, C8, R9, Note that the frequency of the saw-
VRI, R10 tooth wave is determined by the RC
VR2 time constants in the collector circuit.
Voltage The saw-tooth is fed to the voltage
comparator comparator formed by QO7 and QO8.
Q07, Q08 Q08 is forward biased through the
FINE control (VR3 paralleled by R12)
R11 and R28. The current flow in Q08
is controlled by the FINE control
(VR3), which. varies its base-emitter
voltage. Q07 conducts only when the
base voltage becomes higher than the
emitter voltage which is determined by
the current flow in QO8. Note that the
emitter voltage of QO8 serves as a
reference voltage.
Referring to Fig. 1-3, the comparator
operates as follows: At time T1 a saw-
tooth signal is applied to the base of
Q07.
At time T2 the voltage at the base of
Q07 is sufficient to turn on QO7
generating a negative pulse.
Note that the pulse width is determined
by saw-tooth signal waveform:

Stage/Control
Buffer/phase
inverter
Q09, Q010,
Q011
Low pass filter
/buffer
amplifier
De amplifiers
Q4, QS,
Q6
Function
Q09 and QO11 is an emitter follower
but Q010 acts as a phase inverter
providing a positive pulsating signal to
the following stages.
Buffer amplifier Q3 and an RC network
consisting of R15, C11, R16, C12, C13
R17 and C14 comprise a low-pass
filter having a sharp rolloff charac-
teristic. .
Notice that this stage acts as an
integrator, converting the input positive
pulses into a dc voltage proportional to
the input pulse width.
De output from the low-pass filter is
applied to the base of Q4. As Q4, Q5
and Q6 are directly coupled, ‘a change
in input dc voltage alters the con-
duction of Q6, controlling the voltage
applied to the motor.
_ Servo Operation
When, by any cause, the motor speed
becomes slightly faster or slower than
the specified value, the servo system
works as follows:
Referring to Fig. 1-3, assume that the
motor speed becomes faster. The FG
output signal frequency becomes
higher, resulting in a shorter interval
between pulses for triggering the saw-
tooth wave generator. The shorter
—_ 1 1 - ;
| oem |
ee
When motor speed becomes faster.
Stage/Control
Power supply
D8, D9
C17,C19
D7
Speed
selector
switch S1
normal
—— |
i —
When motor speed becomes slower.
Function
interval between trigger pulses causes
lower saw-tooth wave height, which in
turn yeilds a shorter “ON”? period for
comparator QO7. Therefore, the output
pulse width at the emitter circuit of
QO11 becomes shorter, reducing the
positive bias upon .Q4.
As a result, the collector-emitter
impedance of Q6 increases, reducing
the motor speed.
Conversely, if the motor speed becomes
slower, the collector-emitter impedance
of Q6 decreases, increasing the motor
speed.
A positive 12 volts for the system is
provided by the full-wave rectifier
consisting of D8 and D9, filter ca-
pacitors C19, C17 and zener diode D7.
Speed changeover operation is per-
formed by changing the saw-tooth wave
frequency as previously described.
Since the saw-tooth wave frequency is
determined by the RC time constant
in the collector circuit of Q06, a speed
selector switch is connected in parallel
with VR2 and R10. A smaller time
constant results in faster motor speed
and vice versa. So S1 is open when the
speed selector switch is. set to
33-1/3 rpm.
slower
FG output signal
collector of QO2
pase of Q06
collector of Q06
collector of Q07
base of Q3
base of Q6
Fig. 1-3. Waveforms on servo control circuit

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1-3.

SECTION 2
DISASSEMBLY
AND
REPLACEMENT
WARNING
Unplug the ac power cord before start-
ing any disassembly or replacement
procedures.
CAUTION
To avoid damage to the stylus while
performing the following procedures,
make sure that the stylus protecting
cover is in place.
2-1. TOP COVER REMOVAL
1. Open the top cover, and then push the upper
hinge toward the left to release the lock as
shown in Fig. 2-1.
2. Carefully lift the top cover straight up. This
frees the top cover.
Fig. 2-1: Top cover removal
2-2, BOTTOM PLATE REMOVAL
1, Flip the wooden case upside down. Place it on
a soft protective pad, and then remove the six
screws (@ PS 3 x 16) securing the bottom plate |
to the wooden case as shown in Fig. 2-2. This
frees the bottom plate.
2-3. TURNTABLE BASE REMOVAL —
Preparation
1. Remove the bottom plate as described in Pro-
cedure 2-2.
2. ~— Up to serial No. 50,550 — (AEP Model Only)
Disconnect 4-p AMPLOK connector from bot-
tom of the turntable and then remove the top
cover as described in Procedure 2-1.
— Serial No. 50,551 and later —
(AEP Model Only)
Disconnect 4-p connector from bottom of the
turntable and then remove the top cover as
described in Procedure 2-1.
Procedure
1.
_ Remove the rubber mat from the turntable, and -
- then insert your fingers into the two holes of
the turntable. with both thumbs placed on the
center spindle as shown in Fig. 2-3.
Carefully lift the turntable straight up: ; a
Remove the three screws ( @©P 5 x 16) and two
screws ( @® PS 4x 20) securing the turntable
base to the wooden.case. This frees the turn-
table base. See Fig. 2-4.
Note: The turntable base may not be easily
"ss Temovable due to the rubber washer.
inserted between the turntable base and
the wooden case. In: this case, gently
push the motor end from the bottom.
Flip. the turntable base upside down. Place a
support between the turntable base and the
service bench to keep pressure off the motor
spindle.
Fig. 2-3. Turntable removal

Fig. 2-4. Turntable base removal
2-4. SERVO AMPLIFIER CHASSIS REMOVAL
1. Remove the turntable base as described in
Procedure 2-3.
2. Remove the four screws (@ PS 4 x 6) securing
the chassis to. the turntable base as shown
in Fig. 2-5. Thisfrees the chassis.
i
@. P 3.x 6, self-tapping
servo amp cover remova
ii
Fig. 2-5. Bottom view
2-5. SERVO AMPLIFIER COVER REMOVAL
1, Remove the servo amplifier chassis as described
in Procedure 2-4.
2; Remove the two self-tapping screws(@ P 3 x 6)
securing the servo amplifier cover as shown in
Fig. 2-5, and then slide it in the direction shown
by the arrow as illustrated. This frees the cover.
chassis removal
POWER SUPPLY CHASSIS REMOVAL
Note: The power supply chassis is an angled
member on which the power trans-
former, power transistor and fuse holder
are attached.
Remove the turntable base as described in
Procedure 2-3.
Remove the two screws ( @ PS 4 x 8) and
securing the power transformer cover to the
heat sink as shown in Fig. 2-6, if necessary.
Remove the three screws (@ PS 4 x 25)
securing the chassis to the turntable base or the
bracket, as shown in Fig. 2-5. This frees the
power supply chassis.
Fig. 2-6. Power transformer cover removal
MOTOR REPLACEMENT
Remove the turntable base as described in
Procedure 2-3.
Remove the two seilf-tapping screws (@ P 4x 6)
securing the metal cover over the terminal strip
as shown in Fig. 2-5.
Unsolder the motor lead wires at the terminal
strip, and then remove the four screws
(@ PS 4 x 12) securing the motor to the turn-
table base from the top as shown in Fig. 2-7.
Install the replacement motor.

Fig. 2-7. Motor removal
CAUTION
Electromagnetic brake adjustment
(clearance between turntable and magnet
turntable
To FG coil To Motor
co LK “"
~ }
test point
ac21+2V 3
Fig. 2-9. Test point for electromagnetic
brake adjustment
2-8. MICROSWITCH REPLACEMENT
mounted on turntable base) should be
Performed, ab Zollows after replacing: the 1. Remove the turntable base as described in
PIOPOES Procedure 2-3.
1. First of all, confirm that the turntable 2. Unhook the spring pressing the microswitch
does not touch with the magnet on the holding shaft against its bracket. Carefully
turntable base (See Fig. 2-8). If it does, draw out the microswitches along with their
adjust the magnet height by replacing holding shaft as shown in Fig. 2-10.
i ACR OUS Diaks. 3. Remove the retaining rings at one side of the
Three kind of mounting plate are
available as specified in table below.
To remove the magnet and mounting
plate, apply a few drops of cement
solvent to them.
shaft, and then replace the defective micro-
switch as shown in Fig. 2-10.
To. reassemble, reverse the aforementioned
procedure.
[EP Model] 1 [AEP Model]
Description Thickness of plate (mm) | Part Number
Mounting plate, ; 1.6 4-8 08-445-02
5 magnet 1.0 4-8 08-445-11
0.5 4-8 08-445-21
2. Set the turntable for 33-1/3 rpm
operation, and then measure the voltage
applied to the motor at the 5-p termi-
nal strip as shown in Fig. 2-9. It
should be within the limits of 21 +2
volts ac. If not, readjust the clearance
between the turntable and the magnet
by replacing the mounting plate as
previously described.
SS Qe
SH
Fig. 2-10. Microswitch replacement

2-9. STROBE LAMP REPLACEMENT
1.
2.
3.
4.
Remove the turntable base as described in
Procedure 2-3.
Remove the four screws (@ PS 4 x 8)
securing the strobe unit to the turntable base.
Pull out the unit.
Unhook the retaining spring from the lamp
cover and then apply a drop of cement solvent
to the lamp. Wait a few seconds, and then push
out the defective lamp as shown in Fig. 2-11.
CAUTION
Too much cement solvent may cause
damage to the unit. Only a few drops are
required to dissolve the rubber-base ad-
hesive.
Install a new strobe lamp. Take care that the
glowing side (front) of the lamp is positioned
as shown in Fig. 2-11
Note: Apply a drop of rubber-base adhesive
to the rear side of the lamp when
installing the lamp.
glowing
side
Fig. 2-11. Strobe lamp removal
and installation
2-10. POWER TRANSISTOR REPLACEMENT
1.
2;
3.
Remove the power supply chassis as described
in Procedure 2-6.
Remove the screw (@ P 3 x 10) securing the
power transistor to the heat sink.
Cut the emitter and base leads of the defective
power transistor with a diagonal cutter.
This prevents mica-washer damage when remov-
ing the defective power transistor.
When replacing the power transistor, apply a
coating of heat-transferring grease to both
sides of the insulation mica washer.
Any excess grease squeezed out when the
‘mounting. screw is tightened should be wiped
off. with a clean cloth. This prevents it from
2-11,
2-12.
accumulating conductive dust particles that
might eventually cause a short:
TONEARM ASSEMBLY REMOVAL
Remove the shell head.
: Remove the bottom plate as described in Pro-
cedure 2-2.
Unsolder the leads from. the terminal beneath
the turntable base (See Fig. 2-12).
The lead wires are coded as follows:
White ...........0000. L-CH
BUG ic670 3 enon ans L-CH (ground)
Reds conn eines t edie R-CH
Green ...........00005 R-CH (ground)
Remove the hexagon nut securing the tonearm
base to the wooden case.
This frees the tonearm assembly.
Fig. 2-12. Lead wire connection
TONEARM BASE REMOVAL
Remove the tonearm assembly as described in
Procedure 2-11.
_ Remove the lock lever by turning it counter-
clockwise.