Technics SL-PS740A - Page 13

ADJUSTMENT POINTS
© Servo P.C.B.
Laser power adj. Focus offset adj. Servo.
P.C
R3562
( Resistor )
Note:
Use connector pins to check servo circuit voltages and waveforms.
Measuring Instruments
* Playability test disc (SZZP1054C).
* Normal disc (Ordinary musical program disc).
(1) LASER POWER ADJUSTMENT
the test disc (SZZP1054C).
Oscilloscope setting:
VOLT one 20mV
SWEEP............ 0.2msec.
INPUT............ DC
1. Connect the oscilloscope’s CH1 probe across (+)
and (—) of R3501 (Resistor) on the servo P.C.B.
2. Switch the player power ON, and play track No. 1 on
3. Adjust VR3520 so that the voltage is -50=2mvV.
SL-PS740A
POINTS FOR CHECKING OF SERVO
CIRCUIT’S VOLTAGE AND WAVEFORM
(Refer to pages 14~16.)
Servo P.C.B. HF GND
Disc holder
HF
SU/RD
HFD
TL
DODS
DIVS
RE dig RAD out
es TRAY SW
Bi -8.0V
Be -5.0V
GND
+49V MOTOR +
“77V MOTOR —
Loading motor
* Dual-beam oscilloscope with bandwidth of 30MHz or
better (with EXT trigger and 1: 1 probe).
(2) FOCUS OFFSET ADJUSTMENT
1. Connect the oscilloscope’s CH1 probe across R3562
(Resistor) (+) and Jumper (—) on the servo P.C.B.
2. Switch the player power ON, and play track No. 1 on
the test disc (SZZP1054C).
3. Adjust VR3569 until the signal amplitude become in
the center of 400mV.
Oscilloscope setting:
~13-