Electrical Adjustment - Sony CMT-SP55TC Service Manual

Note :
1. CD Block is basically designed 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
BD board
TP(FEO)
TP(VC)
Procedure :
1. Connect oscilloscope to TP (FEO).
2. Connect between TP (FEI) and TP (VC) by lead wire.
3. Connect between TP (AGCCON) and TP (DGND) by lead wire.
4. Press the "/1 button (TA).
5. Load a disc (YEDS-18) and actuate the focus search. (In
consequence of open and close the disc tray, actuate the focus
search)
6. Confirm that the oscilloscope waveform (S-curve) is
symmetrical between A and B. And confirm peak to peak level
within 4 ±1 Vp-p.
S-curve waveform
7. After check, remove the lead wire connected in step 2 and 3.
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
BD board
TP(RF)
TP(VC)
Procedure :
1. Connect oscilloscope to TP (RF).
2. Connect between TP (AGCCON) and TP (DGND) by lead wire.
3. Press the "/1 button (TA).
4. Load a disc (YEDS-18) and playback.
5. Confirm that oscilloscope waveform is clear and check RF signal
level is correct or not.
6. After check, remove the lead wire connected in step 2.
SECTION 4

ELECTRICAL ADJUSTMENT

Oscilloscope
symmetry
A
within 4 ±1Vp-p
B
oscilloscope
Note: Clear RF signal waveform means that the shape "◊" can be
clearly distinguished at the center of the waveform.
RF signal waveform
E-F Balance (1 Track jump) Check
BD board
TP (TEO)
TP (VC)
Procedure:
1. Connect oscilloscope to TP (TEO) and TP (VC) board.
2. Press the "/1 button (TA).
3. Load a disc (YEDS-18) and playback the number five track.
4. Press the H button. (Becomes the 1track jump mode.)
5. Confirm that the level B and A (DC voltage) on the oscilloscope
waveform.
1 track jump waveform
0V
level=1.3±0.6Vp-p
A
Specification level: x 100=less than ±22%
B
6. After check, remove the lead wire connected in step 1.
RF PLL Free-run Frequency
Procedure :
1. Connect frequency counter to test point (XPCK) with lead wire.
BD board
TP (XPCK)
2. Press the "/1 button (TA).
3. Put the disc (YEDS-18) in to play the number five track.
Confirm that reading on frequency counter is 4.3218MHz.
VOLT/DIV : 200mV
TIME/DIV : 500ns
level : 1.45 ± 0.3Vp-p
oscilloscope
+
–
Center of
waveform
B
A (DC voltage)
Symmetry
frequency counter
+
–
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