Service manual
32
5-6. 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 11).
5-6-1. Temperature Compensation Offset Check
When performing adjustments, set the internal temperature and
room temperature of 22 °C to 28 °C.
Checking Procedure:
1. Press the l m or M L button to display “TEMP
CHECK”.
2. Press the ENTER/YES “R” 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)
5-6-2. Laser Power Check
Before checking, check the IOP value of the optical pick-up.
(Refer to 8. Recording and Displaying IOP Information)
Connection :
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
l m
button or M L 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 (MD) board.
2. Then, press the l m or M L button to display
“LDPWR CHECK”.
3. Press the ENTER/YES “R” button once to display “LD 0.9 mW
$ ”. Check that the reading of the laser power meter become
0.84 to 0.92 mW.
4. Press the ENTER/YES “R” 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
±10%
5. Press the MENU/NO “R” button to display “LDPWR CHECK”
and stop the laser emission.
(The MENU/NO “R” button is effective at all times to stop the
laser emission)
Optical pick-up
objective lens
laser
power mete
r
+
–
BD (MD) board
digital voltmete
r
CN110 pin
5
(I+3V)
CN110 pin
4
(IOP)
KMS260A
27X40
B0825
lOP=82.5 mA in this case
lOP (mA) = Digital voltmeter reading (mV)/1 (Ω)
(Optical pick-up label)
Note 1: After step 4, each time the ENTER/YES “R” button is pressed,
the display will be switched “LD 0.7 mW $ ”, “LD 6.2 mW $
”, and “LD Wp $ ”. Nothing needs to be performed
here.
5-6-3. Traverse Check
Connection :
Checking Procedure:
1. Connect an oscilloscope to CN110 pin 3 (TEO) and CN110
pin 1 (VC) on the BD (MD) board.
2. Load a disc (any available on the market). (Refer to Note 1)
3. Press the M L button to move the optical pick-up outside
the pit.
4. Press the l m or M L button to display “EF MO
CHECK”.
5. Press the ENTER/YES “R” button to display “EFB = MO-R”.
(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 press the l m or
M L button.
(Read power traverse checking)
Traverse Waveform
7. Press the ENTER/YES “R” button to display “EFB = MO-W”.
8. Observe the waveform of the oscilloscope, and check that the
specified value is satisfied. Do not press the l m or
M L button.
(Write power traverse checking)
Traverse Waveform
+
–
oscilloscope
(DC range)
V: 0.1 V/div
H: 10 ms/div
BD (MD) board
CN110 pin
3
(TEO)
CN110 pin
1
(VC)
A
B
VC
Specified value : Below 10% offset value
Offset value (%) = X 100
IA – BI
2 (A + B)
A
B
VC
Specified value : Below 10% offset value
Offset value (%) = X 100
IA – BI
2 (A + B)
+
–
oscilloscope
(DC range)
10 pF
330 k
Ω
CN110 pin
3
(TEO)
CN110 pin
1
(VC)
BD (MD) board
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.