Pioneer PD-M630 Service Manual page 42

Multi- play compact disc player

Hide thumbs Also See for PD-M630:

Regular screwdriver

Twin-tray CD type adjustment locations

Multi-play CD type adjustment locations

[How to find the null point]

When you insert the regular screwdriver into the slit for the grating adjustment and change the grating angle, the am-

plitude of the tracking error signal at TP1 Pin 2 changes. Within the range for the grating, there are five or six loca-

tions where the amplitude of the wave reaches a minimum. Of these five or six locations, there is only one at which

the envelope of the wave form is smooth. This location is where the three laser beams divided by the grating are all

right above the same track. (See Figure 3.)

This point is called the null point. When adjusting the grating, this null point is found and used as the reference posi-

tion.

Turing the grating counter-clockwise ad Turning the grating clockwise (*1)

(1) For Multi-play CD type,

the directions are reversed.

Wave form of TP, Pin2 iw li nav

(Wy rv lH) rave

Null

point

Grating adjustment position

Figure 3

NYA

Null point wave form

Maximum amplitude

Wave form other than

wave form

the null point