Sony DVP-M35 Operation Manual page 34

The Servo DSP IC provides the following control in the tracking servo system.
(a) Tracking gain adjustment
The gain of internal digital filter of IC is automatically adjusted so that the tracking
servo loop gain becomes optimum.
Consequently, the optimum gain for each disc to be played can be attained, besides
correction of gain variations in tracking actuator (coil) and optical pickup sensor
(photodiode for tracking and focusing).
(b) Tracking jump control
At one track jump or N track jump (jumping many tracks) in asearching, generation
of tracking pulses, control of tracking brake, and measurement of tracking jumps
are executed.
The TE (Tracking Error) signal input to IC506 (Servo DSP CXD8730R) is low frequency
boosted, high frequency phase compensated, and gain adjusted by the internal digital
filter, and output from DSP by the DSP internal D/A converter as the tracking drive
signal (T OUT @P).
The T OUT signal is input to the IC (IC363:BA5981) for
driving the tracking actuator (coil).
In IC363, voltage amplification, voltage conversion, and current amplification are carried
out to BTL drive the tracking actuator (coil) using the output signals of IC363 (DVD
TRK + @P, DVD TRK - @P).
The tracking zero-cross timing is generated by IC501 (pPC393) and IC508 (NJM3404).