Pioneer MU-3000

Commentary

A direct-drive phono motor developed by applying the Hall element developed by Pioneer.

By adopting a direct drive system in which the rotation of the motor itself is the same as the number of revolutions of the record, there is no reduction mechanism that causes uneven rotation, and the generation of vibration that increases in proportion to the number of revolutions is reduced.
In addition, we have adopted a DC drive Hall motor that applies a Hall element to detect the magnetic field of the switching mechanism. Compared with a mechanical switching mechanism motor using a brush, vibration is less and S/N and durability are improved.

The Hall element is a magnetic-to-electric conversion element with a structure in which a potential difference is generated at the output terminal when a current is passed through the input terminal and a perpendicular magnetic field is applied to the input terminal. This is called the Hall effect. An alloy of N-type InSb is evaporated on a cross-shaped substrate, and four input / output lines are provided there. This is a type of semiconductor molded with synthetic resin material.
Pioneer has developed a vacuum deposition method and succeeded in rationalizing the production process and increasing the thickness of the ultra-thin film from 30-50 μ m to 0.8 μ m. Moreover, uniform quality improves the performance of Hall elements.
In the MU-3000, three Hall elements are placed at the bottom of the stator core for sequential switching.

The MU of the MU 3000 consists of a rotor magnet magnetized to 20 poles and a 3-phase wave-wound stator with two pairs of 60-slot windings.
Three Hall elements are arranged on a part of the stator side. The Hall elements generate signals to activate the transistor circuit by magnetic field lines in sequence with the rotation of the magnet rotor magnetized with 20 poles. The transistor circuit changes the current supply to each winding in sequence according to the signals to generate rotational driving force.

A DC servo mechanism has been adopted in order to obtain more precise accuracy of constant speed.
This servomechanism uses the back electromotive force generated in the coil by the rotation of the magnet rotor to control the rotation. Since the back electromotive force increases and decreases in proportion to the rotation, this change is detected and the electronic circuit accurately controls the drive current.

33 1/3, 45 rpm speed switching uses a purely electronic circuit.
In addition, there is a speed fine adjustment knob that can be adjusted independently for each rotational speed, and it can be freely controlled within ± 2%.

Since it uses a DC motor, it can be used regardless of the power frequency of 50Hz/60Hz.

Model Rating

Type	Phono motor
Motor	Brushless DC Servo Hole Motor (20 Pole 60 Slot)
Drive system	Direct drive
Turntable	31 cm Diameter Aluminum Alloy Die-cast (1.7 kg)
Number of revolutions	33 1/3, 45 rpm, fine adjustment possible
Rotational speed adjustment range	± 2% or less, independent adjustment of each speed
Speed change	Electronic
Startup time	1/2 Rotation, Within 1.3 Seconds (33 1/3rpm)
Uneven rotation	0.03% or less (WRMS)
S/N	60 dB or more
Attachment mechanism	Rotational speed fine adjustment knob Strobe light Level
Semiconductor used	Transistor : 23 Diode : 17 pcs Hall element : 3 pieces
Power supply voltage	100 VAC, 50Hz/60Hz
Rated power consumption	5W
External dimensions	Width 330x Height 121x Depth 370 mm
Weight	10kg