Schematic (See attached pdf):

Sensors: Speed sensor

Похожее изображение

And auto-stop sensor. Both are optical. Currently, two comparators are added to control signal. 

Main MCU: MSP430G2553.

Outputs:

Motor PWM controller, which generates 1.8v voltage to stabilize speed.

Tonarm shorterer, which pulling down tonarm when Motor is stopped.

PCB:

Fully compatible with old pcb by dimensions and connections. One-side PCB 125x127mm.