User:Zaxour/Basic CD Adjustment

Tools needed: Small screwdriver (ESD safe, plastic) to adjust potentiometer knobs Oscilloscope with persistence (Rigol DS series, old analog scope, etc)

Setup Set the oscilloscope time base to 500ns per division and voltage scale to 500 mV per division. Termination should be set to 1M or higher (most scopes are default to 1M) Set the coupling for the desired channel to AC mode. Set the trigger to positive, and set the trigger level around 100 mV. Move the horizontal position to around 10-20% (1-2 divisions) to be able to clearly see the waveform. Set the triggering mode to Auto. For best results, turn on persistence so that waveforms will stay on the screen and create the eye pattern.

Record the pin-to-pin resistances of the potentiometers before performing adjustments. This allows returning to original values in case something unexpected occurs during adjustment.

Locate the 6 pin header between VR101 and IC108's pins. Pin 2 is the RF summing amplifier output monitoring pin. Attach the oscilloscope probe to pin 2 and the ground to the nearest ground connection.

Using a pressed music CD, turn the system on and press "RUN" to go to the CD player menu. Begin playing the disc and observe the waveform. The peak-to-peak amplitude of the waveform (measured from top to bottom) should be around 1.25 Vpp, +/- 0.1V.

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If the waveform is too low, adjust VR102 to change the amplitude of the waveform. If the amplitude cannot get high enough, an adjustment to the potentiometer on the pickup assembly may be required.

After the correct amplitude is achieved, observe the waveform to make sure that the "diamond" shapes are clearly discernable. If no diamond is clearly visible, begin adjusting VR104 until they are.