Electrical Adjustments; Cd Section; Video Section - Sony MCE-SV7 Service Manual

ELECTRICAL ADJUSTMENTS

CD SECTION

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
Oscilloscope
BD board
TP(FEO)
TP(DVC)
Procedure :
1. Connect an oscilloscope to TP (FEO) and TP (DVC).
2. Connect between TP (FEI) and TP (VC) by lead wire.
3. Turn Power switch on.
4. Load the disc (YEDS-18) and actuate the focus search. (In
consequence of open and close the disc tray, actuate the focus
search)
5. 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
symmetry
A
within 4 ±1Vp-p
B
7. 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
brightness to obtain best waveform.
RF Level Check
oscilloscope
BD board
TP (RFAC) or TP(RFDC)
TP(DVC)
Procedure :
1. Connect an oscilloscope to TP (RFAC) and TP (DVC).
2. Turn Power switch on.
3. Load the disc (YEDS-18) and playback.
4. Confirm that the oscilloscope waveform is clear and check RF
signal level is correct or not.
5. Measure the RFDC in the same way.
SECTION 5
Note: Clear RF signal waveform means that the shape "◊" can be
clearly distinguished at the center of the waveform.
RF signal waveform
VOLT/DIV : 200mV
TIME/DIV : 500ns
level : 1.1 ± 0.3Vp-p
E-F Balance (1 Track jump) Check
oscilloscope
BD board
TP (TEO) +
TP (DVC) –
Procedure:
1. Connect an oscilloscope to TP (TEO) and TP (DVC).
2. Turn Power switch on.
3. Load the disc (YEDS-18) and playback the number five track.
Press the X button. (Becomes the 1track jump mode.)
4.
5. Confirm that the level B and A (DC voltage) on the oscilloscope
waveform.
1 track jump waveform
B
0V
Symmetry
level=1.3 ±0.6Vp-p
A
x 100=less than ±22%
Specification level:
B
6. After check, remove the lead wire connected in step 1.
RF PLL Free-run Frequency Check
Procedure :
1. Connect a frequency counter to TP (XPCK) and GND.
frequency counter
BD board
TP (XPCK) +
–
2. Turn Power switch on.
3. Load the disc (YEDS-18) and playback the number five track.
4. Confirm that the reading on frequency counter is 4.3218MHz.
Checking Location :
[ BD BOARD ] — SIDE B —
R120
TP (DVC)
TP (FEI)
TP (FEO)
TP (TEO)
TP (RFDC)
IC101
TP
IC103
(RFAC)
TP (VC)
Center of
waveform
A (DC voltage)
11 11

VIDEO SECTION

Video Frequency Adjustment
Connection:
VMP board
TP (27MHz)
TP (GND)
Procedure:
1. Connect a frequency counter to TP (27MHz) and TP (GND).
2. Turn power switch on.
[FUNCTION]
3. Turn the knob of amplifier unit (TA-SV7AV) to
set the CD function.
4. Adjust CT503 on the VMP board so that the frequency counter
TP (XPCK)
reading 27.0 MHz ± 80 Hz at stop status.
Adjustment Location:
[VMP BOARD] (SIDE A)
J301
CN501
TP (27MHz)
CN502
MCE-SV7
frequency counter
IC507
TP (GND)
CT503
Video
Frequency
Adjustment