Sanyo TP 747 Service Manual

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SERVICE MANUAL A
75 SANYO

STEREO TURNTABLE

TP 7(le

SPECIFICATIONS

MOTOR 81 TURNTABLE SECTION

Motor

Drive System

Speeds

Speed Change

Turntable Platter
Diameter
Weight

Wow & Flutter

Signal to Noise Ratio

Speed Adjustment Range

TONEARM SECTION
Type

Effective Length

Cue Control
Anti-Skating System
Lateral Balance

DC Servo Motor

Belt Drive

33-1/3 & 45 rpm
Electronic Control
Aluminum Alloy Die-Cast
308 mm

0.7 Kg

0.05 %

60 dB

13.0 %

Static Blance Type (S-Shape)
222 mm

Viscous Damped (Down only)
Calibrated - Spring Type

Fix weight

Cartridge Weight Range
With Headshell

Minimum Tracking Pressure

Tracking Error

Counterweight Calibration

Antiskate Calibration

GENERAL

Power Requirement
Power Consumption
Dimension (W)x(D)x(H)
Weight

AC:

20 gr

1.5 gr
+3°, -1°

0 to 3.0 gr
0 to 4.0 gr

120 V, 60 HZ

4.0 W

17-1/4"x6-l/ "x14-7/8"
17 lbs.

*Specifications are subject to change without notice.

WM-1833

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BLOCK DIAGAM 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 converted 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
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SPEED ADJUSTMENT

o This unit is built-in F-G- SERVO circuit and the speed has been adjusted accurately in the factory.
o 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.

MOTOR P.C.B SPEED ADJUST VR

@@

- - +
0 33am 45R.P.M O

BOTTOM VIEW

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