Read Sony MDS-JB940 Service Manual online
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.
section “AUTO CHECK”. Therefore, normally do not check them.
1. Traverse Check
Connection :
Connection :
Checking Procedure:
1.
1.
Connect an oscilloscope to CN105 pin 4 (TE) and CN105
pin 6 (VC) on the BD board.
pin 6 (VC) on the BD board.
2.
Load a recordable disc (MDW-74/GA-1).
3.
Press the M button to move the optical pick-up outside the
pit.
pit.
4.
Turn the l AMS L knob to display “EF MO
CHECK”(C14).
CHECK”(C14).
5.
Press the YES button to display “EFB =
MO-R”.
6.
Observe the waveform of the oscilloscope, and check that the
specified value is satisfied. Do not turn the l AMS L
knob.
specified value is satisfied. Do not turn the l AMS L
knob.
Traverse Waveform
7.
Press the YES button to display “EFB =
MO-W”.
8.
Observe the waveform of the oscilloscope, and check that the
specified value is satisfied. Do not turn the l AMS L
knob.
specified value is satisfied. Do not turn the l AMS L
knob.
Traverse Waveform
9.
Press the YES button to display “EFB =
MO-P”.
Then, the optical pick-up moves to the pit area automatically
and servo is imposed.
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.
knob.
Traverse Waveform
+
–
–
Oscilloscope
(DC range)
V: 0.1 V/div
H: 10 ms/div
H: 10 ms/div
BD board
CN105 pin 4 (TE)
CN105 pin 6 (VC)
CN105 pin 6 (VC)
A
B
VC
Specified value : Below 10% offset value
Offset value (%) =
× 100
IA – BI
2 (A + B)
A
B
VC
Specified value : Below 10% offset value
A
B
VC
Specified value : Below 10% offset value
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”
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 =
CD”. Servo is
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.
knob.
Traverse Waveform
17. Press the YES button to display “EF CD CHECK”.
18. Press the EJECT A button and take out the test disc (TDYS-
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.
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”.)
(Refer to “5-5. Creating Continuously-Recorded Disc”.)
2.
Turn the l AMS L knob to display “CPLAY 1 MODE”
(C34).
(C34).
3.
Press the YES button to display “CPLAY 1MID”.
4.
Press the MENU/NO button when “C =
AD =
” is
displayed.
5.
Turn the l AMS L knob to display “FBIAS CHECK”
(C16).
(C16).
6.
Press the YES button to display “
/
c =
”.
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.
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 “
/
b =
”.
Check that the C1 error is about 100 and ADER is below 2.
8.
Press the YES button to display “
/
a =
”.
Check that the C1 error is about 100 and ADER is below 2.
9.
Press the MENU/NO button, then press the EJECT A button
and take out the test disc.
and take out the test disc.
A
B
VC
Specified value : Below 10% offset value
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