Sony MDS-JB930 Service Manual page 24

6. CHECK PRIOR TO REPAIRS
These checks are performed before replacing parts according to
"approximate specifications" to determine the faulty locations. For
details, refer to "Checks Prior to Parts Replacement and Adjust-
ments" (See page 8).
6-1. Temperature Compensation Offset Check
When performing adjustments, set the internal temperature and
room temperature of 22 C to 28 C.
Checking Procedure:
[ AMS ]
±
1. Turn the ≠
(C01).
[YES]
2. Press the button.
3. "T=@@(##) [OK" should be displayed. If "T=@@ (##) [NG"
is displayed, it means that the results are bad.
(@@ indicates the current value set, and ## indicates the value
written in the non-volatile memory)
6-2. Laser Power Check
Before checking, check the IOP value of the optical pick-up.
(Refer to 8. Recording and Displaying IOP Information)
Connection :
Optical pick-up
objective lens
BD board
CN110 pin 5 (I +3V)
CN110 pin 4 (IOP)
Checking Procedure:
1. Set the laser power meter on the objective lens of the optical
pick-up. (When it cannot be set properly, press the 0 but-
[ ]
ton or ) button to move the optical pick-up)
Connect the digital voltmeter to CN110 pin 5 (I+3V) and
CN110 pin 4 (IOP) on the BD board.
[ AMS ]
2. Then, turn the ≠
CHECK" (C02).
[YES]
3. Press the button once to display "LD 0.9 mW $
Check that the reading of the laser power meter become 0.84
to 0.92 mW.
[YES]
4. Press the button once more to display "LD 7.0 mW $
". Check that the reading the laser power meter and digital
voltmeter satisfy the specified value.
Specified Value:
Laser power meter reading : 7.0 ± 0.2 mW
Digital voltmeter reading : Value on the optical pick-up label
(Optical pick-up label)
KMS260A
27X40
B0825
lOP=82.5 mA in this case
lOP (mA) = Digital voltmeter reading (mV)/1 ( )
[MENU/NO]
5. Press the button to display "LDPWR CHECK"
and stop the laser emission.
[MENU/NO]
(The button is effective at all times to stop the
laser emission)
24
knob to display "TEMP CHECK"
laser
power meter
digital voltmeter
+
–
[ ]
±
knob to display "LDPWR
±10%
Note 1: After step 4, each time the
will be switched "LD 0.7 mW $
"LD Wp
6-3. Traverse Check
Note 1:Data will be erased during MO reading if a recorded disc is
used in this adjustment.
Note 2:If the traverse waveform is not clear, connect the oscilloscope
as shown in the following figure so that it can be seen more
clearly.
BD board
CN110 pin 3 (TEO)
CN110 pin 1 (VC)
Connection :
BD board
CN110 pin 3 (TEO)
CN110 pin 1 (VC)
Checking Procedure:
1. Connect an oscilloscope to CN110 pin 3 (TEO) and CN110
pin 1 (VC) on the BD board.
2. Load a disc (any available on the market). (Refer to Note 1)
[ ]
3. Press the ) button to move the optical pick-up outside the
pit.
[ AMS ]
4. Turn the ≠
CHECK"(C03).
[YES]
5. Press the
(Laser power READ power/Focus servo ON/tracking servo
OFF/spindle (S) servo ON)
6. Observe the waveform of the oscilloscope, and check that the
specified value is satisfied. Do not turn the
knob.
(Read power traverse checking)
Traverse Waveform
VC
".
Specified value : Below 10% offset value
Offset value (%) =
[YES]
7. Press the
8. Observe the waveform of the oscilloscope, and check that the
specified value is satisfied. Do not turn the
knob.
(Write power traverse checking)
Traverse Waveform
VC
Specified value : Below 10% offset value
Offset value (%) =
[YES]
button is pressed, the display
", "LD 6.2 mW $
$ ". Nothing needs to be performed here.
oscilloscope
(DC range)
330 k
+
–
10 pF
oscilloscope
(DC range)
+
V: 0.1 V/div
–
H: 10 ms/div
±
knob to display "EF MO
button to display "EFB =
[ AMS ]
≠
I A – B I
X 100
2 (A + B)
button to display "EFB =
[ AMS ]
≠
I A – B I
X 100
2 (A + B)
", and
MO-R".
±
A
B
MO-W".
±
A
B