Pioneer CDX-M12 Service Manual page 15

@ How to seek the null point
When the screwdriver is inserted in the slit for grating adjustment while the angle of the
grating is varied, the ampli-
tude of the TEY tracking error signal varies.
There are 5 or 6 positions where the amplitude of the waveform is decreased in the grating variable
range. In only
one of the waveform amplitude diminishing positions, the envelope is made smooth . This position
denotes the
State where three laser beams divided by the grating are aligned right on the same track.
This position is referred to as the null point. Adjust the grating to seek out the null point which is used
as a refer-
ence position in performing the grating adjustment.
Turn the grating Turn the grating
clockwise. counterclockwise.
{
Waveform of
TP 1, Pin 2
= oo
|
ruil
MT Ni
if
mt
7
Grating adjustment —_—Null point
position
~~
Waveform at null point Waveform of maximum Waveform in positions
amplitude other than null point
17