To check that the centre of the spindle motor is on the track of the laser beam.
Note: This adjustment must be performed with the player placed horizontally
Connect the oscilloscope channel 1 to TP1-9 (tracking error) and channel 2 to TP1-4 (Tracking A+C). Use the following oscilloscope settings:
Channel 1: Probe x10, 100mV (if the oscilloscope is faster than 20MHz turn on the bandwidth limiter for the channel) – DC Coupling.
Channel 2: Probe x10, 100mV (if the oscilloscope is faster than 20MHz turn on the bandwidth limiter for the channel) – AC Coupling.
Set the oscilloscope to the X·Y mode in order to observe the Lissajous waveform of the Tracking error signal and the Tracking A+C signal combined.
Put the player in the following condition:
- Service mode
- Play mode
- Tracking servo loop open
- Tilt servo 10:off
Start playing the test disc in test mode with the tracking servo closed. At around frame 1,000 open the tracking servo. Record the Y-axis amplitude of the Lissajous waveform:
Now close the tracking servo and move the pick-up to the outer-edge of the disc (around frame 20,000). Then open the tracking servo. Record the Y-axis amplitude of the Lissajous waveform:
If the Y-axis amplitudes of the two Lissajous waveforms (from the outside and inside of the disc) are different. Perform the pick-up assembly centering adjustment and then retest.