Teac PD-135 - Adjustment Procedures

ADJUSTMENT PROCEDURES
CAUTION:
Avoid eye exposure to invisible laser beam which is emitted from
laser pickup.
PRECAUTIONS REGARDING ADJUSTMENT
e
Adjustment is performed in the indicated order.
e@ When adjustment is made for one item, check the other items
which follow.
@ The laser pick-up has already been precisely adjusted. Do not
touch its mounting screws or controls.
Laser power control knob
— Do not adjust.
@ When the diffraction grid is adjusted, remove the mechanism.
It is convenient to place an insulating panel on top of the chassis
and then to place the mechanism on top of this. (The wires are
connected.)
Insulator Board
(wood, plastic etc.)
® Refer to the adjustment diagram for the test points and adjust-
ment controls.
The ground point for the measurement equipment is the test
point indicated as GND.
REQUIRED EQUIPMENTS
DC Voltmeter
Dualtrace Oscilloscope
Frequency Counter
Signal Generator
Plastic Screwdriver
Diffraction Grating Adjustment Jig
Test Disc (SONY:YEDS4)
CHECKING FOCUS ERROR SIGNAL
Checking the focus error signal of the pick-up allows for an evalu-
ation of the pick-up. Be sure this is carried out before repair.
1.
2.
Turn on the power and set the unit to the STOP mode.
Connect an oscilloscope between test pin FE of connector
CN7 and test pin GND (Set the time axis to 0.5 seconds/
division.)
. Connect test pin GND to the collector of Q125.
4. Press the OPEN/CLOSE button and place the test disk YEDS4
on the table load. Press the OPEN/CLOSE button again.
The waveform shown below is displayed six times on the
oscilloscope when the table load closes. Check that the p-p
voltage is about 2.5V and that the top and bottom of the
waveform are symmetrical.
Repeated six times
Hee c@en es
i 1
' ' ' ' 4
1
1
1
1 1 1
1 1
i 1 4 ‘ 1
' i
1 '
‘ t
' ‘
(When recorded on a memory scope)
l
'
4
1
|
*p-p voltage of 2.5V
*+ and — voltage roughly same