ADC CD-100X (1985)

The model CD-100X utilizes five servo circiuts:

Focal control servo

The astigmatic method is employed for the focus control which utilizes the fact that routing the reflected laser light through a semi-cylidrical lens changes the shape of the bean in accordance with the distance.

Tracking servo

Tracking servo is required to chase disc pit columns since CD systems do not have a guide to lead laser beam to the pit. The model CD-100X employs 3-beam tracking servo system.

Sled servo

The sled servo serves for dual purpose - to gradually move back and forth the entirely of the laser pickup in accordance with the procession of disc playing; and to move it quickly for searching tracks. The lens of the laser pickup is able to travel at a small distance to follow the pits when playing with the entire pickup stopped. As it approaches the limit of the travelable range, DC components come to be contained in the tracking servo signals. The sled servo acts to detect the DC components and maintains the lens to be in the middle of the moveable range, namely to maintain the DC component to be zero.

Auto Power Controller (APC) circuit

The APC circuit is provided to maintain the constant laser output level in spite of the variation in temperature etc. The monitor diode located in the close proximity of the lens feeds back the variation to keep the current flowing through the diode constant.

Constant Linear Velocity (CLV) servo circuit

Unlike analog records, the rotation of compact disc is 500 rpm in inner area and 200 rpm in outer area. The CLV servo acts to maintain the proper rotation of the motor. The reference to determine if the rotation is too fast or too slow depends upon the coincidence of the phase of the RF signal to U301 and the reference clock signal.

The laser pickup used for the model CD-100X comprises six photo diodes A to F, diodes A to D, consisting actually of one single diode which is divided vertically and horizontally into four parts, for signal detection and diodes E and F for tracking servo. Since the laser light scintillated onto the surface of compact disc is turbulently reflected by pit area and entirely reflected by no pit area, the digital signals in disc can be read out by detecting the reflected laser light.

Specifications

Audio Section

Frequency response: 5 - 20 kHz ±0.5 dB

Total Harmonic Distortion: 0.004%

Dynamic range: 95 dB

Output level: 2 V rms

Signal-to-noise ratio: -90 dB V

Channel separation: 90 dB at 1 kHz

Output impedance: 600 Ω

Internal system

Optical pickup: 3-beam laser

D/A conversion: 16-bit linear

Filter: Seventh order passive filter

Error correction: CIRC dual error correction system

Functions

Music search: SKIP buttons

Fast forward/reverse: FF and REV buttons

Remaining time display: REMAINING key

program memory function: 16 selections, random

Repeat: of one progral, or all contents

Disc loading: Motor driven, horizontal loading

General

power requirements: 100 - 120 V, 220 - 240 V, 50/60 Hz

Power consumption: 12 W

Dimensions (W x H x D): 341 x 88 x 293 mm (13-7/16" x 3-7/16" - 11-9/16")

Weight: 3.3 kg (7 lbs. 5 oz)