Sony MDS-JB940 Service Manual page 26

5-6-5. Other Checks
All of the following check modes have already been checked in the
section "AUTO CHECK". Therefore, normally do not check them.
1. Traverse Check
Connection :
BD board
CN105 pin 4 (TE)
CN105 pin 6 (VC)
Checking Procedure:
1. Connect an oscilloscope to CN105 pin 4 (TE) and CN105
pin 6 (VC) on the BD board.
2. Load a recordable disc (MDW-74/GA-1).
Press the M button to move the optical pick-up outside the
3.
pit.
4. Turn the l AMS L knob to display "EF MO
CHECK"(C14).
5. Press the YES button to display "EFB =
6. Observe the waveform of the oscilloscope, and check that the
specified value is satisfied. Do not turn the l AMS L
knob.
Traverse Waveform
VC
Specified value : Below 10% offset value
IA – BI
Offset value (%) =
2 (A + B)
7. Press the YES button to display "EFB =
8. Observe the waveform of the oscilloscope, and check that the
specified value is satisfied. Do not turn the l AMS L
knob.
Traverse Waveform
VC
Specified value : Below 10% offset value
9. Press the YES button to display "EFB =
Then, the optical pick-up moves to the pit area automatically
and servo is imposed.
10. Observe the waveform of the oscilloscope, and check that the
specified value is satisfied. Do not turn the l AMS L
knob.
Traverse Waveform
VC
Specified value : Below 10% offset value
26
Oscilloscope
(DC range)
+
V: 0.1 V/div
–
H: 10 ms/div
MO-R".
A
B
× 100
MO-W".
A
B
MO-P".
A
B
11. Press the YES button to display "EF MO CHECK"
The disc stops rotating automatically.
12. Press the EJECT A button and take out the disc.
13. Load the check disc (MD) TDYS-1.
14. Turn the l AMS L knob and display "EF CD CHECK"
(C15).
15. Press the YES button to display "EFB =
imposed automatically.
16. Observe the waveform of the oscilloscope, and check that the
specified value is satisfied. Do not turn the l AMS L
knob.
Traverse Waveform
VC
Specified value : Below 10% offset value
17. Press the YES button to display "EF CD CHECK".
18. Press the EJECT A button and take out the test disc (TDYS-
1).
2. Focus Bias Check
Change the focus bias and check the focus tolerance amount.
Checking Procedure :
1. Load the recorded test disk (MDW-74/GA-1).
(Refer to "5-5. Creating Continuously-Recorded Disc".)
Turn the l AMS L knob to display "CPLAY 1 MODE"
2.
(C34).
3. Press the YES button to display "CPLAY 1MID".
4. Press the MENU/NO button when "C =
displayed.
5. Turn the l AMS L knob to display "FBIAS CHECK"
(C16).
6. Press the YES button to display "
The first four digits indicate the C1 error rate, the two digits
after [/] indicate ADER, and the 2 digits after [c =] indicate the
focus bias value.
Check that the C1 error is below 20 and ADER is below 2.
7. Press the YES button to display "
Check that the C1 error is about 100 and ADER is below 2.
8. Press the YES button to display "
Check that the C1 error is about 100 and ADER is below 2.
Press the MENU/NO button, then press the EJECT A button
9.
and take out the test disc.
CD". Servo is
A
B
AD = " is
/ c = ".
/ b = ".
/ a = ".