Electrical Adjustment - Sony MHC-RG270 Service Manual

HCD-GX355/GX555/RG270/RG475/RG575
CD SECTION
Note:
1. CD Block is basically designed to operate without adjustment.
Therefore, check each item in order given.
2. Use YEDS-18 (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.
•
Abbreviation
MX: Mexican model
S-CURVE CHECK
CD board (except MX)
BD board (MX)
Procedure:
1. Connect an oscilloscope to TP (FE) and TP (VC) on the CD
board (except MX) or BD board (MX).
2. Press the button to turn the power on.
I/1
3. Load the disc (YEDS-18) and actuate the focus search. (In
consequence of open and close the disc tray, actuate the focus
search)
4. Confirm that the oscilloscope waveform (S-curve) is
symmetrical between A and B. And confirm peak to peak level
within 3 ± 0.5 Vp-p.
S-curve waveform
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.
Connecting Location: CD board (except MX)
BD board (MX)
RFAC LEVEL CHECK
CD board (except MX)
BD board (MX)
TP(RFACO)
TP(VC)
Procedure:
1. Connect an oscilloscope to TP (RFACO) and TP (VC) on the
CD board (except MX) or BD board (MX).
2. Press the button to turn the power on.
I/1
3. Load the disc (YEDS-18) and playback.
4. Confirm that oscilloscope waveform is clear and check if RFAC
signal level is correct or not.
Note: Clear RFAC signal waveform means that the shape " ◊ " can be clearly
distinguished at the center of the waveform.
Connecting Location: CD board (except MX)
BD board (MX)
20
SECTION 5
ELECTRICAL ADJUSTMENTS
oscilloscope
TP(FE)
TP(VC)
symmetry
A
within 3 ± 0.5 Vp-p
B
oscilloscope
RF signal waveform
– CD BOARD (Conductor Side) (except MX) –
– BD BOARD (Conductor Side) (MX) –
TP
(VC)
TP
(FE)
VOLT/DIV : 200mV
TIME/DIV : 500ns
level : 1.3 ± 0.3 Vp-p
IC101
TP
(RFACO)