Sharp MD-M3 Service Manual page 22

MD-M3/M1
Lead-in switch position measurement mode
Insert High reflection test disk (TGYS1)
Note: Adjust the lead-in switch position to FF85 to FFDF.
1. Loosen the screw (A) x 2 pcs. which fix the mechanism switch
PWB.
2. Retighten the screw, pressing the mechanism switch PWB in
the arrow direction, and then measure the lead-in switch
position again.
After position adjustment fix with the two screws (A). (See Fig. 22-1.)
Note: After tightening the two screws on the PWB apply Screw Lock.
Forced rotation of loading motor
When STOP or EJECT appears in the display and the VOLUME
CONTROL knob is rotated (up or down), it allows the loading motor
to be forced to run (loading and unloading operations).
Adjustment of magnetic head mounting position
When the magnetic head and optical pickup have been replaced, be
sure to adjust the mounting position.
For easier adjustment of mounting position move the optical pickup
to the center position, and then adjust the position.
1. Set the adjusting transparent disc 3.
2. Lower the magnetic head up-shift arm with your finger, and raise
the magnetic head.
3. Viewing the set from above, make an adjustment so that the
magnetic head aligns with the optical pickup objective lens.
4. Make sure that there is a clearance as shown in Figure 22-2 and
the magnetic head moves up and down smoothly.
Mechanism Adjustment
1. Optical pickup grating inspecting method
43 Pin of IC1101
GND (TP1125)
100K
26 Pin of IC1101
EOUT (TP1129)
470p
470p
25 Pin of IC1101
FOUT (TP1130) 100K
Figure 22-3 Optical Pickup Grating Deviation
Measuring Method
After the automatic adjustment has been performed in the AUTO
mode (test mode) using the low reflection test disk MMD212 (TEAC)
("COMPLETE" will have been displayed), adjust the Lissajous
waveform (x-y) using EOUT and FOUT.
1. Slightly loosen the 3 screws of spindle motor, and make an
adjustment, observing the Lissajous's waveform.
2. After the adjustments are complete, tighten the screws in numerical
order: 1 , 2 and then 3 . (See Fig. 22-4.)
a
OSILLOSCOPE
GND CH1 CH2
b
X Y
LISSAJOUS'S WAVEFORM
Less than a:b = 4:1
Loosen the
two screws (A).
Mechanism Switch PWB
Magnetic head
Objective lens
Radial direction
Spindle Motor
Adjusting hole
3
Spindle motor
1
adjusting
hole
2
– 22 –
Lead In Switch
Figure 22-1
Tangential direction
Push
Magnetic head
Figure 22-2
1
3
2
Check the Lissajou's waveform,
shifting the mounting position with
a screwdriver (to be fitted into the
disc motor adjusting hole).
Figure 22-4