Sony MDS-JB730, Service Manual

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6-4. Focus Bias Check
Change the focus bias and check the focus tolerance amount.
Checking Procedure :
1. Load the test disk (MDW-74/AU-1).
2. Turn the
[ AMS ]
knob to display “CPLAY MODE”
(C30).
3. Press the
[YES]
button twice to display “CPLAY MID”.
4. Press the
[MENU/NO]
button when “C = AD = ” is
displayed.
5. Turn the
[ AMS ]
knob to display “FBIAS CHECK”
(C05).
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 50 and ADER is below 2.
7. Press the
[YES]
button to display “ / b = ”.
Check that the C1 error is about 200 and ADER is below 2.
8. Press the
[YES]
button to display “ / a = ”.
Check that the C1 error is about 200 and ADER is below 2.
9. Press the
[MENU/NO]
button, then press the
[EJECT ]
but-
ton and take out the test disc.
6-5. C PLAY Checking
MO Error Rate Check
Checking Procedure :
1. Load the test disk (MDW-74/AU-1).
2. Turn the
[ AMS ]
knob to display “CPLAY MODE”
(C30).
3. Press the
[YES]
button to display “CPLAY MID”.
4. The display changes to “C = AD = ”.
5. If the C1 error rate is below 80, check that ADER is below 2.
6. Press the
[MENU/NO]
button to stop playback, then press the
[EJECT ]
button and take out the test disc.
CD Error Rate Check
Checking Procedure :
1. Load the check disc (MD) TDYS-1.
2. Turn the
[ AMS ]
knob to display “CPLAY MODE”
(C30).
3. Press the
[YES]
button twice to display “CPLAY MID”.
4. The display changes to “C = AD = ”.
5. Check that the C1 error rate is below 50.
6. Press the
[MENU/NO]
button to stop playback, then press the
[EJECT ]
button and take out the check disc.
6-6. Self-Recording/playback Check
Prepare a continuous recording disc using the unit to be repaired
and check the error rate.
Checking Procedure :
1. Load a recordable disc (blank disc).
2. Turn the
[ AMS ]
knob to display “CREC MODE”
(C31).
3. Press the
[YES]
button to display “CREC MID”.
4. When recording starts, light up “
REC
” and display “CREC
@@@@” (@@@@ is the address).
5. About 1 minute later, press the
[MENU/NO]
button to stop
continuous recording.
6. Turn the
[ AMS ]
knob to display “CPLAY
MODE” (C30).
7. Press the
[YES]
button to display “CPLAY MID”.
8. “C = AD = ” will be displayed.
9. Check that the C1 error becomes below 80 and the AD error
below 2.
10. Press the
[MENU/NO]
button to stop playback, then press the
[EJECT ]
button and take out the disc.
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.
10. Observe the waveform of the oscilloscope, and check that the
specified value is satisfied. Do not turn the
[ AMS ]
knob.
Traverse Waveform
11. Press the
[YES]
button to display “EF MO CHECK”
The disc stops rotating automatically.
12. Press the
[EJECT ]
button and take out the disc.
13. Load the check disc (MD) TDYS-1.
14. Turn the
[ AMS ]
knob and display “EF CD CHECK”
(C04).
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
[ AMS ]
knob.
Traverse Waveform
17. Press the
[YES]
button to display “EF CD CHECK”.
18. Press the
[EJECT ]
button and take out the check disc.
± ≠
A
B
VC
Specified value : Below 10% offset value
Offset value (%) = X 100
I A – B I
2 (A + B)
§
±
≠
± ≠
A
B
VC
Specified value : Below 10% offset value
Offset value (%) = X 100
I A – B I
2 (A + B)
§
§
±
≠
±
≠
§
± ≠
§
± ≠
± ≠
§
±
≠