HCD-LX7/LX8
17
17
6-1. CIRCUIT BOARDS LOCATION
CD SECTION
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
Procedure :
1. Connect the oscilloscope to test points TP (FE) and TP (VC).
2. Connect TP (FE1) and GND, and TP (AGCCON) and GND of
the BD board with lead wires.
3. Press the "/1 button to turn the set ON.
4. With the disc (YEDS-18) loaded, press the HX button and
perform focus search. (Focus search will be performed in the
same way even while the disc table is pushed in and out.)
5. Check the symmetry and peak to peak level of the oscilloscope
waveform (S curve) at this time.
S-curve waveform
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.
RF Level Check
Procedure :
1. Connect oscilloscope to test point TP (RF) and TP (VC) on BD
board.
2. Press the "/1 button to turn the set ON.
3. Put disc (YEDS-18) in and playback 5 track.
4. Confirm that oscilloscope waveform is clear and check RF sig-
nal level is correct or not.
Note: Clear RF signal waveform means that the shape “◊” can be
clearly distinguished at the center of the waveform.
RF signal waveform
Adjustment Location :
[ BD BOARD ] — SIDE A —
Procedure:
1. Connect oscilloscope to test point TP (TE) on BD board.
2. Press the "/1 button to turn the unit ON.
3. Put disc (YEDS-18) in to play the number five track.
4. Press the HX button.
5. Check the level B of the oscilloscope's waveform and the A (DC
voltage) of the center of the Traverse waveform.
Confirm the following:
• A/B x 100 = less then ± 22 (%)
• B = 1.3 ± 0.6 Vp-p
1 track jump waveform
E-F Balance (1 Track Jump) check
oscilloscope
BD board
TP (FE)
TP (VC)
+
–
symmetry
A
B
Within 3 ± 1 Vp-p
oscilloscope
BD board
TP (RF)
TP (VC)
+
–
VOLT/DIV : 200mV
TIME/DIV : 500ns
level : 1.45 ± 0.25 Vp-p
0V
Center of the waveform
B
Symmetry
A (DC voitage)
level : 1.3 ± 0.6 Vp-p
oscilloscope
BD board
TP (TE)
TP (VC)
+
–
TP
(VC)
TP
(RF)
TP
(TE)
TP
(FE1)
TP (FE)
TP
(AGCCON)
SECTION 6
DIAGRAMS
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