Sony HCD-RG490 Service Manual page 21

CD SECTION
Note:
1. CD Block is basically constructed to operate without adjustment.
2. Use YEDS-18 disc (3-702-101-01) unless otherwise indicated.
3. Use an oscilloscope with more than 10 M 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.
5. Check the focus bias check when optical pick-up block is replaced.
Abbreviation
MX: Mexican model
FOCUS BIAS CHECK
CD board (Except RG490: MX/RG590: MX)
BD board (RG490: MX/RG590: MX)
TP (RFACI)
TP (VC)
Procedure :
1. Connect oscilloscope to TP (RFACI) and TP (VC) on the CD
board (Except RG490: MX/RG590: MX) or BD board
(RG490: MX/RG590: MX).
2. Press the button to turn the power on, and press
I/1
the button to open the CD disc table.
A
3. Set disc (YEDS-18) on the tray and press the
playback.
4. Confirm that oscilloscope waveform is as shown in the figure
below. (eye pattern)
A good eye pattern means that the diamond shape ( ) in the
center of the waveform can be clearly distinguished.
Connecting Location:
– CD Board (Conductor Side)
(Except RG490: MX/RG590: MX) –
oscilloscope
(DC range)
+
–
button to
7
– BD Board (Conductor Side) (RG490: MX/RG590: MX) –
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
level:
0.9 0.4 Vp-p
IC201
TP
(VC)
TP
(RFACI)
TP
(VC)
HCD-RG490/RG590
IC201
TP
(RFACI)
21