Sony PS-2250 - Technical Description; Technical Specifications; AC Servo System Principle

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