Cd Section - Sony CMT-A70 Service Manual

CD SECTION

Note:
1. Perform all CD section check in the CD Test Mode.
(Refer to page 16)
2. Use the PATD-012 disc (Part No.: 4-225-203-01).
3. Use an oscilloscope with more than 10 MΩ 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.
TRAVERSE CHECK
oscilloscope
(DC range)
CD board
TP (TE) +
–
TP (VC)
Procedure:
1. Connect an oscilloscope to TP (TE) and TP (VC) on the CD
board.
2. Load the disc (PATD-012).
3. Press the three buttons of , [MODE/DIR] and [CLOCK]
x
simultaneously to enter the CD Test Mode and display "88"
(Initial mode).
4. Press the button to enter the FOCUS1 mode and
CD u
display "F-".
5. Confirm that the center level of waveform is 0 V.
6. Confirm that the Vp-p value of waveform is 0.35 to 1.1 V.
VOLT/DIV: 0.2 V (with the 10:1 probe in use)
TIME/DIV : 1 ms
Vp-p
0 V
FOCUS BIAS CHECK
oscilloscope
(AC range)
CD board
TP (RF) +
–
TP (VC)
Procedure:
1. Connect an oscilloscope to TP (RF) and TP (VC) on the CD
board.
2. In the FOCUS1 mode, press the button to enter the
CD u
ALL SERVO mode and display "P-".
3. Confirm that the oscilloscope waveform is as shown in the
below figure. (eye pattern)
A good eye pattern means that the diamond shape "◊" in the
center of the waveform can be clearly distinguished.
VOLT/DIV: 0.2 V (with the 10: 1 probe in use.)
TIME/DIV: 200 ns
0.6 to 1.2 Vp-p
When observing the eye pattern, set the oscilloscope
for AC range and raise vertical sensitivity.
CMT-A50/A70
Checking Location:
– CD Board (Conductor Side) –
TP
(VC)
TP
(TE)
TP
(RF)
IC702
19 19
CMT-A50/A70