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Q Q
ELECTRICAL ADJUSTMENTS
3 7 6 3 1 5 1 5 0
DECK SECTION
0 dB=0.775 V
Note: Confirm each contents of this section first of all. If the results are
not satisfied, do the adjustment.
1.
Demagnetize the record/playback head with a head
demagnetizer.
2.
Do not use a magnetized screwdriver for the adjustments.
3.
After the adjustments, apply suitable locking compound to the
parts adjust.
4.
The adjustments should be performed with the rated power
supply voltage unless otherwise noted.
5.
The adjustments should be performed in the order given in this
service manual. (As a general rule, playback circuit adjustment
should be completed before performing recording circuit
adjustment.)
6.
The adjustments should be performed for both L-CH and R-
CH.
7.
Switches and controls should be set as follows unless otherwise
specified.
• Test Tape
Tape
Signal
Used for
P-4-A100
10 kHz, –10 dB
Azimuth Adjustment
WS-48B
3 kHz, 0 dB
Tape Speed Adjustment
P-4-L300
315 Hz, 0 dB
Level Adjustment
Record/Playback Head Azimuth Adjustment
Procedure:
1.
Mode: Playback
T E
L
1 3 9 4 2 2 9 6 5 1 3
test tape
MAIN board
P-4-A100
SPEAKER terminals (SJ301)
(10 kHz, –10 dB)
L-CH, R-CH
level meter
set
+
–
w w w
.
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SECTION 4
2.
Turn the adjustment screw and check output peaks. If the peaks
do not match for L-CH and R-CH, turn the adjustment screw
so that outputs match within 1dB of peak.
within
L-CH
1 dB
peak
Output
level
R-CH
peak
Screw
position
L-CH
R-CH
peak
peak
3.
Mode: Playback
MAIN board
test tape
SPEAKER terminals (SJ301)
P-4-A100
L-CH
oscilloscope
(10 kHz, –10 dB)
L-CH
MAIN
V
board
CN301
set
R-CH
R-CH
waveform of oscilloscope
in phase 45°
90° 135° 180°
good
wrong
4.
Repeat step 1 to 3 in playback (REV) mode.
5.
After the adjustments, apply suitable locking compound to the
pats adjusted.
Adjustment Location:
reverse
forward
x
a o
y
i
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8
CD SECTION
Notes:
1. CD block basically constructed to operate without adjustment. There-
fore, check each item in order given.
2. Use YEDS-18 disc (Part No.: 3-702-101-01) unless otherwise indicated.
3. Use the oscilloscope with more than 10 MΩ impedance.
4. Clean an object lens by an applicator with neutral detergent when the
signal level is low than specified value with the following checks.
within
1 dB
S-Curve Confirmation
Connection:
CD board
Screw
IC703 pin qg
position
TP (VC)
Procedure:
1. Connect an oscilloscope to IC703 pin qg and TP (VC) on the
CD board.
2. Connect between TP (FOK) and TP (GND) on the CD board
by lead wire.
3. Turn the power ON.
[EJECT
]
H
4. Press the
Z
(CD) button to open the disc tray, and
put the disc (YEDS-18).
[EJECT ]
5. Press the
Z
(CD) button to close the disc tray (Actu-
ate the focus search).
6. Confirm that the waveform on the oscilloscope is symmetrical
between A and B and that peak to peak level is within 3.0 ±
1.0 Vp-p.
Q
Q
3
7
6
3
1
S-curve waveform
7. After confirmation, disconnect the lead wire in step 2.
Note: • Try to measure several times to make sure that the ratio of A : B
or B : A is more than 10 : 7.
• Take sweep time as long as possible and light up the brightness
to obtain best waveform.
RF Level Confirmation
Connection:
CD board
IC703 pin qh
TP (VC)
Procedure:
1. Connect an oscilloscope to IC703 pin qh and TP (VC) on the
CD board.
2. Turn the power ON.
3. Load the disc (YEDS-18), and press the
back the disc.
4. Confirm that the waveform on the oscilloscope is clear and
u 1 6 3
that the RF signal level is correct.
Note: Clear RF signal waveform means that the shape "◊" can be clearly
.
distinguished at the center of the waveform.
13
13
2
4
9
9
8
RF signal waveform
When observing the eye pattern, set the oscilloscope for AC range
oscilloscope
and raise vertical sensitivity.
Connecting Location:
+
–
– CD Board (Conductor Side) –
TP (FOK)
5
1
5
0
8
9
2
4
9
symmetry
A
within 3.0 ± 1.0 Vp-p
B
oscilloscope
(AC range)
+
–
[
]
u
button to play-
m
c o
HCD-VP100
2
9
9
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
(with the 10: 1 probe
in use)
+0.25
level: 1.3
Vp-p
–0.20
TP (GND)
IC701
TP (VC)
20
11
IC703
8
2
9
9
1
10
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