Sony MDS-JB940 Service Manual page 30

5-13. FOCUS BIAS ADJUSTMENT
Adjusting Procedure :
1. Load the continuously-recorded disc (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 1 MID".
4. Press the MENU/NO button when "C =
displayed.
5. Turn the l AMS L knob to display "FBIAS ADJUS"
(C09).
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 [a =] indicate the
focus bias value.
7. Turn the l AMS L knob clockwise and find the focus
bias value at which the C1 error rate becomes about 200.
8. Press the YES button to display "
9. Turn the l AMS L knob counterclockwise and find
the focus bias value at which the C1 error rate becomes about
200. The C1 error rate must be almost same as the value set at
step 7.
10. Press the YES button to display "
11. Check that the C1 error rate is below 20 and ADER is 00. Then
press the YES button.
12. If the "( )" in " - -
button.
If below 20, press the MENU/NO button and repeat the
adjustment from step 2.
13. Press the EJECT A button and take out the disc.
Note 1: The relation between the C1 error and focus bias is as shown in the
following figure. Find points A and B in the following figure using
the above adjustment. The focal point position C is automatically
calculated from points A and B.
Note 2: As the C1 error rate changes, perform the adjustment using the
average value.
5-14. ERROR RATE CHECK
5-14-1. CD Error Rate Check
Checking Procedure :
1. Load the check disc (MD) TDYS-1.
2. Turn the l AMS L knob and display "CPLAY 1
MODE" (C34).
3. Press the YES button and display "CPLAY 1 MID".
4. The display changes to "C =
5. Check that the C1 error rate is below 20.
6. Press the MENU/NO button to stop playback, then press the
EJECT A button and take out the check disc.
5-14-2. MO Error Rate Check
Checking Procedure :
1. Load the continuously-recorded disc (MDW-74/GA-1). (Refer
to "5. Creating Continuously-Recorded Disc")
2. Turn the l AMS L knob to display "CPLAY 1 MODE"
(C34).
3. Press the YES button to display "CPLAY 1 MID".
4. The display changes to "C1 =
5. If the C1 error rate is below 20, check that ADER is 00.
6. Press the MENU/NO button to stop playback, then press the
EJECT A button and take out the test disc.
30
AD = " is
/ a = ".
/ b = ".
/ c = ".
( )" is above 20, press the YES
AD = ".
AD = ".
5-15. FOCUS BIAS CHECK
Change the focus bias and check the focus tolerance amount.
Checking Procedure :
1. Load the continuously-recorded disc (MDW-74/GA-1). (Refer
to "5. Creating Continuously-Recorded Disc")
Turn the l AMS L knob to display "CPLAY 1 MODE"
2.
(C34).
3. Press the YES button twice to display "CPLAY 1 MID".
4. Press the MENU/NO button when "C =
displayed.
Turn the l AMS L knob to display "FBIAS CHECK"
5.
(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 and display "
Check that the C1 error is about 100 and ADER is below 2.
8. Press the YES button and display "
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 disc.
Note: If the C1 error rate and ADER are above other than the specified
value at points a (step 8. in the above) or b (step 7. in the above),
the focus bias adjustment may not have been carried out properly.
Perform the adjustment from the beginning again.
5-16. AUTO GAIN CONTROL OUTPUT LEVEL
ADJUSTMENT
Be sure to perform this adjustment when the optical pick-up is
replaced.
If the adjustment results becomes "Adjust NG!", the optical pick-
up may be faulty or the servo system circuits may be abnormal.
5-16-1. CD Auto Gain Control Output Level Adjustment
Adjusting Procedure :
1. Load the check disc (MD) TDYS-1.
Turn the l AMS L knob to display "AG Set (CD)"
2.
(C11).
3. When the YES button is pressed, the adjustment will be
performed automatically.
"Complete!!" will then be displayed momentarily when the
value is recorded in the non-volatile memory, after which the
display changes to "AG Set (CD)".
4. Press the EJECT A button and take out the check disc.
5-16-2. MO Auto Gain Control Output Level Adjustment
Adjusting Procedure :
1. Load the test disc (MDW-74/GA-1).
Turn the l AMS L knob to display "AG Set (MO)"
2.
(C10).
3. When the YES button is pressed, the adjustment will be
performed automatically.
"Complete!!" will then be displayed momentarily when the
value is recorded in the non-volatile memory, after which the
display changes to "AG Set (MO)".
Press the EJECT A button and take out the test disc.
4.
AD = " is
/ c = ".
/ b = ".
/ a = ".