Technics SL-P202A - Page 12

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Measuring Instruments
* Playability test disc (SZ2ZP1054C).
* Normal disc.
* Dual-beam oscilloscope with bandwidth of 30MHz or
better (with EXT trigger and 1:1 probe).
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(1) LASER POWER ADJUSTMENT
1. Connect the oscilloscope’s CH1 probe across (+) and (—)
of R3501 (Resistor) on the servo P.C.B.
Switch the player power ON, and play track No. 1 on the
test disc (SZZP1054C).
Adjust VR3520 so that the voltage is —-50 + 2mV.
2:
3.
Oscilloscope setting:
+
|
«pe-+
(2) FOCUS OFFSET ADJUSTMENT
1. Connect the oscilloscope’s CH1 probe across (+) and (—)
of R3562 (Resistor) 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 400mvV.
Oscilloscope setting:
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SWEEP ew ae vtate 0.2msec. SWEEP o eteos sc haet 4 50msec.
T T f a l — oa
+. + + - t
= |
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(3) PLL ADJUSTMENT
1. Connect CH1 of the oscilloscope to the LINE OUT
terminal (either of Lch or Rch) and ground.
Oscilloscope setting: VOLT...... 1V
SWEEP..... 1msec.
INPUT ..... DC
2. Switch the player power ON, and play track No. 6
(wedge 0.7mm) on the test disc (SZZP1054C).
3. Check the waveform displayed on the oscilloscope and
adjust VR501 in the following steps.
Step 1. Turn VR501 clockwise slowly and observe the
point at which the waveform on the oscilloscope
begins to be disturbed.
Step 2. Turn VR501 counterclockwise slowly and observe
the point at which the waveform on the oscilloscope
begins to be disturbed.
Step 3. Set VR501 in the middle between the points
observed in the above steps ‘'1"' and “2”.
_’ Noise started to appear in output sound with
- VR501 turned counterclockwise.
“ 2
s 1
/ Noise started to appear in output sound with
S VR501 turned clockwise.
Final setting point.
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(4) CHECK OF PLAY OPERATION AFTER ADJUSTMENT
* Checking Skip Search
1. Play an ordinary musical program disc.
2. Press the skip button to check for normal skip search
operation (in both the forward and reverse directions).
Checking Manual Search
1. Play an ordinary musical program disc.
. Press the manual search button to check for smooth
manual search operations at either low or high speed
(in both the forward and reverse directions).
* Playability check by test disc
1. Play the 0.7 mm black dot and the 0.7 mm wedge on the
defect test disc (SZZP1054C) and verify that no sound
skip or noise occurs.
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