Sony MDS-JB920 Service Manual page 26

[YES]
9. Press the button 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 rotate the
knob.
(Traverse Waveform)
VC
Specified value : Below 10% offset value
I A – B I
Offset value (%) =
2 (A + B)
[YES]
11. Press the button display "EF MO CHECK"
The disc stops rotating automatically.
[ EJECT]
12. Press the § button and remove the disc.
13. Load the check disc (MD) TDYS-1.
[ AMS ]
±
14. Roteto the ≠
(C04).
[YES]
15. Press the button and display "EFB =
imposed automatically.
16. Observe the waveform of the oscilloscope, and check that the
specified value is satisfied. Do not rotate the
knob.
(Traverse Waveform)
VC
Specified value : Below 10% offset value
Offset value (%) =
2 (A + B)
[YES]
17. Press the button and display "EF CD CHECK".
[ EJECT]
18. Press the § button and remove the check disc (MD)
TDYS-1.
MO-P".
[ AMS ]
≠
A
B
X 100
knob and display "EF CD CHECK"
CD". Servo is
[ AMS ]
≠
A
B
I A – B I
X 100
6-4. Focus Bias Check
Change the focus bias and check the focus tolerance amount.
Checking Procedure :
1. Load a test disk (MDW-74/AU-1).
[ AMS ]
± 2. Rotate the ≠
(C30).
[YES]
3. Press the
[MENU/NO]
4. Press the
displayed.
[ AMS ]
5. Rotate the ≠
(C05).
[YES]
6. Press the
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 220 and ADER is below 2.
[YES]
7. Press the
Check that the C1 error is below 220 and ADER is below 2.
[YES]
8. Press the
Check that the C1 error is below 220 and ADER is below 2.
[MENU/NO]
9. Press the
ton, and remove the test disc.
6-5. C PLAY Checking
MO Error Rate Check
±
Checking Procedure :
1. Load a test disk (MDW-74/AU-1).
[ AMS ]
2. Rotate the ≠
(C30).
[YES]
3. Press the
4. The display changes to "C =
5. If the C1 error rate is below 80, check that ADER is below 2.
[MENU/NO]
6. Press the
[ EJECT]
§ button, and test disc.
CD Error Rate Check
Checking Procedure :
1. Load a check disc (MD) TDYS-1.
[ AMS ]
2. Rotate the ≠
(C30).
[YES]
3. Press the
4. The display changes to "C =
5. Check that the C1 error rate is below 50.
[MENU/NO]
6. Press the
[ EJECT]
§ button, and the test 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. Insert a recordable disc (blank disc) into the unit.
[ AMS ]
2. Rotate the ≠
(C31).
[YES]
3. Press the
4. When recording starts, "
"CREC @@@@" (@@@@ is the address), and recording
starts.
5. About 1 minute later, press the
continuous recording.
[ AMS ]
6. Rotate the
MODE"(C30).
[YES]
7. Press the
8. "C = AD =
9. Check that the C1 error becomes below 80 and the AD error
below 2.
[MENU/NO]
10. Press the
[ EJECT] §
button and remove the disc.
– 26 –
± knob and display "CPLAY MODE"
button twice and display "CPLAY MID".
button when "C =
± knob and display "FBIAS CHECK"
button and display " /
button and display " /
button and display " /
button, next press the
± knob and display "CPLAY MODE"
button and display "CPLAY MID".
AD = ".
button, stop playback, press the
± knob and display "CPLAY MODE"
button twice and display "CPLAY MID".
AD = ".
button, stop playback, press the
± knob to display "CREC MODE"
button to display the "CREC MID".
REC
" is displayed, this becomes
[MENU/NO]
≠ ±
knob to display "C PLAY
button to display "C PLAY MID".
" will be displayed.
button to stop playback, and press the
AD = " is
c = ".
b = ".
a = ".
[ EJECT]
§
but-
button to stop