47 Laboratory PiTracer CD Transport

Direct drive with a highly sensitive, low inertia, high torque coreless mortor (spindle diameter 3mm).

Thread drive mechanism with a combination of coreless motor, Kevlar core thread, and V guide system. This mechanism was developed to adjust the pickup-head itself to the off centering of CD. The lens, which changes the angle in conventional CD transport to adjust to the off centering, stops its movement almost competely. It dramatically lessens the fractuation of the servo amount, also allowing the laser beam to hit the surface of CD at constant 90 degrees for greater acuracy of focus.

The platform, machined out of 320w x 30h x 360d mmm aluminum block, contains the spindle motor, sled motor, worm gear, V guide track, mortor drive amp and output connectors.

The head casing is machined out of 270w x 30h x 170d mm aluminum block. The pickup head (CEC), circuitry and control keys are centralized on it to release the movement of the pickup head from the stress of the multiconductor cable.

Four operation amplifiers, same grade as the one used in 4706 Gaincard, are used to control the spindle motor and the sled motor. With the combination of the simple mechanism, we realized a smooth and quick analog management.

Both are machined out of solid acrylic. The CD touches the turntable only at its inside and outside edges when it's clamped down, minimizing the effect of the turntable material and overdamping. The spindle and the turntable were machined again after the assembly using a custom machining device to ensure the right angle. The exact location of the turntable, the guide track and the pickup head is also adjusted by a custom tool developed for the purpose.

PiTracer is powered by Model 4700 Power Humpty. By adding another 4700, you can power the motor drive section and the pickup circuitry separately.