Sanyo TP 727 Service Manual

Page 1

S ERVI C E MAN UAL

r23 SANYo

STEREO TURNTABLE TP 727
(U. SA) I
SPECIFICATIONS
MOTOR & TURNTABLE SECTION Cartridge Weight Range
Motor DC Servo Motor With Headshell 20 gr
Drive System Belt Drive Minimum Tracking Pressure 15 gr
Speeds 33-1/3 81 45 rpm Tracking Error +3°, -1u
Speed Change Electronic Control Counterweight Calibration O to 3.0 gr
Turntable Platter Aluminum Alloy Die-Cast Antiskate Calibration 0 to 4.0 gr
Diameter 308 mm
Weight 0.7 Kg
Wow & Flutter 0,05 % GENERAL
Signal to Noise Ratio 60 dB Power Requirement AC: 120 V4 60 Hz
Speed Adjustment Range :30 % Power Consumption 4.0 W

TONEARM SECTION
Type

Effective Length

Cue Control
Anti-Skating System

Static Blance Type (S-Shape)
222 mm

Viscous Damped (Down only)
Calibrated - Spring Type

Specifications are subiect to change without notice.

WM-2046

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BLOCK DIAGRAM OF THE DC SERVO

Principle of Operation

The frequency generator is placed coaxially with the motor shaft. The output signal from the frequency
generator is convened into a rectangular wave in the speed detecting circuit, which is then supplied to
the differentiating circuit to obtain a differentiated wave form synchronized to the frequency of
rotation.

The leading edge of the differentiated wave form is used for switching a transistor ON or OFF to obtain a
saw-tooth wave whose wave peak is proportional to the frequency.

The saw-tooth wave thus generated is compared with a reference voltage obtained from a reference
voltage circuit separately composed, and the portion of the saw-tooth wave exceeding the reference
voltage is taken out as the control signal.

the driving signal for the motor is obtained by integrating the control signal (rectangular pulse).

Motor speed can be adjusted by changing the reference voltage.

Control frequency:

EP disk motor speed 1520 rpm ................. 304 Hz
LP disk motor speed 1130 rpm ................. 226 Hz
Speed detecting Differentiating Saw-tooth wave Comparator Driving
circuit circuit generating circuit circuit circuit
Reference voltage
circuit M
SPEED ADJUSTMENT

0 This unit is built-in F~G~ SE RVO circuit and the speed has been adiusted accurately in the factory.
0 if, for any reason, when you change the speed, turn these volumes with the screwdriver to the "+"
direction or "- direction.
+" direction .......................... This increases the speed.
- direction .......................... This decreases the speed.

SPEED ADJUST VR

MOTOR P.C.B m m
- - +
0 33am 45am 0

BOTTOM VIEW

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