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(3)主轴伺服:RF放大电路TDA1302T⑨脚输出的RF信号输入到SAA7345的⑧脚。RF信号在SAA7345内部,经前置处理后,送到主轴线速度检测器,由其内部的PLL锁相环和VCO电路产生一个连续的、与EFM信号同步的位时钟脉冲,送到主轴电机控制电路中的CLV处理器,与基准时钟信号进行比较,其误差信号由CLV处理器处理成主轴速度伺服控制电压,从SAA7345③、③脚输出,送入TDA7073A(U707)①、②脚,经驱动放大后,从U707(13)、(16)脚输出主轴电机驱动电压加到主轴电机,控制其转速,以保持恒定的线速度。 2.索尼2549+2545机心的伺服电路 CXA2545Q既担任EFM解调,也担任伺服信号处理任务。伺服电路包括:聚焦伺服、循迹伺服、进给伺服和主轴伺服四部分,如图29所示。
(3) Spindle servo: RF amplifier circuit TDA1302T⑨ pin output RF signal input to the SAA7345 ⑧ feet. RF signal in the SAA7345 internal, pre-processed, sent to the spindle speed detector, PLL internal PLL and VCO circuit to produce a continuous, with the EFM signal synchronous clock pulse, sent to the spindle motor control CLV processor circuit, compared with the reference clock signal, the error signal is processed by the CLV processor into a spindle speed servo control voltage from the SAA7345③, ③ pin output, into the TDA7073A (U707) ①, ② feet, driven by amplification After the output from the U707 (13), (16) the spindle motor drive voltage is applied to the spindle motor to control the speed, in order to maintain a constant linear velocity. 2. Sony 2549 + 2545 movement of the servo circuit CXA2545Q both serve as EFM demodulation, but also serve as a servo signal processing tasks. Servo circuit includes: focus servo, tracking servo, feed servo and spindle servo four parts, as shown in Figure 29.