Sony MDS-JB940 Service Manual page 28

5-10. LASER POWER ADJUSTMENT
Check the IOP value of the optical pick-up before adjustments.
(Refer to 5-8. Recording and Displaying IOP Information)
Connection :
Optical pick-up
objective lens
BD board
CN105 pin 1 (I +3V)
CN105 pin 2 (IOP)
Adjusting Procedure :
1. Load the laser power meter into the disc inlet and set it on the
objective lens of the optical pick-up. (When it cannot be set
properly, press the m button or M button to move the
optical pick-up)
Connect the digital voltmeter to CN105 pin 1 (I+3V) and
CN105 pin 2 (IOP) on the BD board.
Turn the l AMS L knob to display "LDPWR ADJUS"
2.
(C04).
3. Press the YES button once to display "LD 0.9 mW $
4. Turn the l AMS L knob so that the reading of the laser
power meter becomes 0.85 to 0.91 mW. Press the YES button
after setting the range knob of the laser power meter, and save
the adjustment results in the non-volatile memory. ("LD SAVE
$ " will be displayed for a moment)
5. Then "LD 7.0 mW $ " will be displayed.
Turn the l AMS L knob so that the reading of the laser
6.
power meter becomes 6.9 to 7.1 mW, press the YES button to
save it. ("LD SAVE $ " will be displayed for a moment)
Note: Do not perform the emission with 7.0 mW more than 15 seconds
continuously.
Then, turn the l AMS L knob to display "LDPWR
7.
CHECK" (C13).
8. Press the YES button once to display "LD 0.9 mW $
Check that the reading of the laser power meter become 0.85
to 0.91 mW.
9. Press the YES button once more to display "LD 7.0 mW $
". Check that the reading the laser power meter and digital
voltmeter satisfy the specified value.
Note down the digital voltmeter reading value.
Specified Value:
Laser power meter reading : 7.0 ± 0.2 mW
Digital voltmeter reading : Value on the optical pick-up label
±10%
(Optical pick-up label)
KMS-260B
27X40
B0825
lOP = 82.5 mA in this case
lOP (mA) = Digital voltmeter reading (mV)/1 (Ω)
10. Press the MENU/NO button to display "LDPWR CHECK"
and stop the laser emission.
(The MENU/NO button is effective at all times to stop the
laser emission.)
11. Turn the l AMS L knob to display "Iop Write"(C05).
28
Laser
power meter
Digital voltmeter
+
–
".
".
12. Press the YES button. When the display becomes
Ref=@@@.@ (@ is an arbitrary number), press the YES
button to display "Measu=@@@.@" (@ is an arbitrary
number).
13. The numbers which can be changed will blink. Input the Iop
value noted down at step 9.
To select the number : Turn the l AMS L knob.
To select the digit : Press the l AMS L knob.
14. When the YES button is pressed, "Complete!" will be
displayed momentarily. The value will be recorded in the non-
volatile memory and the display will become "Iop Write".
Note: After step 4, each time the YES button is pressed, the display will
be switched "LD 0.7 mW $
$ ". Nothing needs to be performed here.
5-11. Iop NV Save
Write the reference value in the non-volatile memory for "Iop
Comparer". Do not perform this operation other than when
performing the laser power adjustment while replacing the OP, etc.
and when replacing IC102 as the reference value is rewritten.
Otherwise, deterioration judgment of the OP is wrong.
Note: Perform this operation when the temperature of the optical pick-up
is almost same as the room temperature.
Operation Procedure:
Turn the l AMS L knob to display "Iop NV Save"
1.
(C06).
2. Press the YES button to display "Iop [stop]".
3. After the display changes to "Iop=xxsave?", press the YES
button.
4. "Complete!" is displayed momentarily and the display changes
to "Iop 7.0mW".
5. After the display changes to "Iop=yysave?", press the YES
button.
6. The "Complete!" message indicates that the operation has
ended.
", "LD 6.2 mW $ ", and "LD Wp