Technics SL-PC25

(7)
TRACKING OFFSET ADJUSTMENT
Note: Make sure that the servo gain adjuster’s gain switch
1.
a
(8)
_
ND
No *
*
NO —
o
is set to position “2”,
Connect the oscilloscope’s CH. 1 probe across
(+) and (~) on the Servo P.C.B., and its
CH. 2 probe (+) to VR102's terminal.
Oscilloscope setting: VOLT......... 100 mV (CH. 1)
100 mV (CH. 2)
SWEEP........ 0.2 ms.
input coupling. . AC (both CH. 1
and 2)
Trigger mode. . ae (trigger
CH
Switch the player power ON, and play pone 9 on the
test disc (SZZP1057C).
Trigger the oscilloscope’s CH. 1 so that the following
waveforms are observed. Adjust VR103 until the dip in
the RF signal envelope on CH. 1 is smooth and the
signal amplitude on CH. 2 is minimized, i.e. when
amplitude A equals amplitude B.
TRACKING BALANCE ADJUSTMENT
. Make sure that the servo gain adjuster’s gain switch is
set to position “2”.
. Set up the AF oscillator output for 1.1 kHz, 600 mVp-p,
and connect it across the OSC and GND terminals on the
servo gain adjuster.
Connect the oscilloscope’s CH. 1 probe across §URAI
(+) and (—) on the Servo P.C.B. and CH. 2 probe
(+) to the OSC terminal on the servo gain adjuster.
Oscilloscope setting: VOLT......... 100 mV (CH. 1)
200 mV (CH. 2)
SWEEP........ 0.1 ms.
Input coupling. .AC (both CH. 1
and 2)
Trigger mode .. .NORM (trigger
CH, 2)
. Switch the player power ON, and play the test disc
(SZZP1014F or SZZP1054C).
CHECK OF PLAY OPERATION AFTER ADJUSTMENT
Checking Skip Search
Play an ordinary musical program disc.
Press the skip button to check for normal ‘skip search
Operation (in both the forward and reverse directions).
Checking Manual Search
. 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).
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Minimize the amplitude or make A = B.
Smooth
envelope
5. Set the servo gain adjuster’s gain switch to position
“4” and adjust VR106 so that the wafveform of the
output section marked with >x is balanced.
6. Disconnect the servo gain adjuster’s leads from the
player.
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xX This section of the waveform must be
balanced.
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Checking Using Defect Disc
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.
Play the middle tracks of the uneven test disc and verify
that no sound skip or noise occurs.