Technicolor - Thomson CDP-CX57 - Manual (Page 17)

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SECTION 6
ELECTRICAL ADJUSTMENTS
Note :
1. CD Block is basically designed to operate without adjustment. There-
fore, 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 10M
Ω 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
11. Turn OFF the power, and remove the lead wire connected at
step 7.
Note : A clear RF signal waveform means that the shape “ ◊ ” can be
clearly distinguished at the center of the waveform.
Procedure :
1. Press the
I / u button and turn ON the power supply.
2. Open the front cover, and press the [PLUS ONE] button.
3. Set the disc (YEDS-18) into the “PLUS ONE” slit.
4. Close the front cover, and chuck the disc.
5. Press the
I / u button and turn OFF the power.
6. Connect the oscilloscope to TP (FE) of the BD board.
7. Connect TP (ADJ) of the MAIN board and connect TP (GND)
with a lead wire.
8. Press the I / u button and turn ON the power.
9. The first track will be played back automatically. When the
[CHECK] button is pressed, “S-JI mode” will be displayed on
the fluorescent indicator tube, and focus search will be repeated.
10. Check the oscilloscope waveform (S-curve) is symmetrical be-
tween A and B. And confirm peak to peak level within 1.8 ±
0.6 Vp-p.
11. Turn OFF the power, and remove the lead wire connected at
step 7.
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 brightness
to obtain best waveform.
RF Level Check
Procedure :
1. Press the
I / u button and turn ON the power supply.
2. Open the front cover, and press the [PLUS ONE] button.
3. Set the disc (YEDS-18) into the “PLUS ONE” slit.
4. Close the front cover, and chuck the disc.
5. Press the
I / u button and turn OFF the power.
6. Connect the oscilloscope to TP (RF) of the BD board.
7. Connect TP (ADJ) of the MAIN board and connect TP (GND)
with a lead wire.
8. Press the I / u button and turn ON the power.
9. Playback the fifth track of the disc.
10. Confirm that oscilloscope waveform is clear and check RF
signal level is correct or not.
E-F Balance (Traverse) Check
The procedure for this checking method differs for when a gen-
eral remote control unit is used and not used.
When a general remote commander is used:
1. Press the
I / u button and turn ON the power supply.
2. Open the front cover, and press the [PLUS ONE] button.
3. Set the disc (YEDS-18) into the “PLUS ONE” slit.
4. Close the front cover, and chuck the disc.
5. Press the
I / u button and turn OFF the power.
6. Connect the oscilloscope to TP (TE) of the BD board.
7. Connect TP (ADJ) of the MAIN board and connect TP (GND)
with a lead wire.
8. Press the I / u button and turn ON the power.
9. Playback the fifth track of the disc.
10. Press the
[3] button on the remote commander. (The tracking
servo and the sledding servo are turned OFF.)
11. Check the level B of the oscilliscope's waveform and the A
(DC voltage) of the center of the Traverse waveform.
Confirm the following :
A/B x 100 = less than ± 10%
BD board
TP (FE)
TP (VC)
+
–
oscilloscope
symmetry
S-curve waveform
within 1.8 ± 0.6 Vp-p
A
B
BD board
TP (RF)
TP (VC) +
–
oscilloscope
(AC range)
level: 1.8 Vp-p +0.3
–0.2
VOLT/DIV : 200 mV
TIME/DIV : 500 ns
RF signal waveform
BD board
TP (TE)
TP (VC)
+
–
oscilloscope
Center of the
waveform
Traverse waveform
B
A (DC voltage)
0 V
level: 0.9 ± 0.45 Vp-p
Traverse waveform
C (DC
voltage)
0 V
Tracking servo
Sled servo
OFF Tracking servo
Sled servo
ON
12. Press the [8] button on the remote control unit. (The tracking
servo and sledding servo are turned ON.) Confirm the C (DC
voltage) is almost equal to the A (DC voltage) is step 11.
13. Turn OFF the power, and remove the lead wire connected at
step 7.