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QQ
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Note:
1. CD Block is basically constructed to operate without adjustment.
Therefore, check each item in order given.
2. Use YEDS-18 disc (3-702-101-01) unless otherwise indicated.
3. Use an oscilloscope with more than 10MΩ impedance.
4. Clean the object lens by an applicator with neutral detergent when
the signal level is low than specified value with the following
checks.
S Curve Check
MAIN board
TP (FE)
TP (VC)
Procedure :
1. Connect the oscilloscope to test points TP (FE) and TP (VC).
2. Connect TP (FEI) and TP (VC) of the MAIN board with lead
wires.
3. Press the 1/u button to turn the set ON.
4. Press the ^ button, load and eject the disc (YEDS-18) to
perform focus search.
5. Check the symmetry and peak to peak level of the oscilloscope
waveform (S curve) at this time.
S-curve waveform
TE
L 13942296513
6. After check, remove the lead wire connected in step 2.
Note: • Try to measure several times to make sure than the ratio of
A : B or B : A is more than 10 : 7.
• Take sweep time as long as possible and light up the bright-
ness to obtain best waveform.
Checking Location : MAIN board
RF Level Check
MAIN board
Procedure :
1. Connect oscilloscope to test point TP (RF) and TP (VC) on MAIN
board.
2. Press the 1/u button to turn the set ON.
3. Put disc (YEDS-18) in and playback No.5track.
4. Confirm that oscilloscope waveform is clear and check RF sig-
nal level is correct or not.
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.
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ELECTRICAL ADJUSTMENT
oscilloscope
+
–
symmetry
A
Within 3.8 ± 1 Vp-p
B
oscilloscope
+
TP (RF)
TP (VC)
–
x
ao
y
i
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SECTION 4
8
Note: Clear RF signal waveform means that the shape "◊" can be
clearly distinguished at the center of the waveform.
RF signal waveform
Checking Location : MAIN board
E-F Balance (1 Track Jump) check
Procedure:
1. Connect oscilloscope to test point TP (TE) and TP (VC) on MAIN
board.
2. Press the 1/u button to turn the unit ON.
3. Put disc (YEDS-18) in and playback No.5track.
4. Press the ^ button, to pause.
5. Check the level (B) of the oscilloscope's waveform and the DC
voltage (A) of the center of the Traverse waveform.
Confirm the following:
Q Q
• A/B x 100 = less then ± 22 (%)
3
6 7
1 3
• B = 1.3 ±
1 track jump waveform
0V
Checking Location : MAIN board
[ MAIN BOARD ] — SIDE A —
u163
.
2 9
9 4
2 8
VOLT/DIV : 200mV
TIME/DIV : 500ns
level : 1.2 ± 0.2 Vp-p
oscilloscope
MAIN board
+
TP (TE)
TP (VC)
–
1 5
0 5
8
2 9
9 4
+0.6
Vp-p
–0.7
Symmetry
+0.6
level : 1.3 ±
Vp-p
–0.7
TP
(FE)
IC303
TP
IC301
(RF)
TP
TP
(TE)
(VC)
TP
(FEI)
m
co
HCD-EX200
9 9
2 8
9 9
Center of the waveform
B
A (DC voitage)
13
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