Sony MDS-SD1, Service Manual

Page: 25 / 64

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5-6. CHECKS 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
Adjustments” (See page 8).
5-6-1. Temperature Compensation Offset Check
When performing adjustments, set the internal temperature and room
temperature to 22 to 28 C.
Checking Procedure:
1. Rotate the –
˜
+ knob to display “TEMP CHECK”.
2. Press the ENTER/YES 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 5-8. Recording and Displaying IOP Information.)
Connection :
KMS 260A
27X40
B0825
N
Iop = 82.5 mA in this case
Iop (mA) = Digital voltmeter reading (mV)/1 (
Ω
)
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
/
≠
button or
)
/
±
button to move the optical pick-up.)
Connect the digital volt meter to CN110 pin
5
(I+3V) and
CN110 pin
4
(IOP).
2. Then, rotate the – ˜ + knob and display “LDPWR CHECK”.
3. Press the ENTER/YES button once and 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 button once more and display “LD 7.0
mW $ ”. Check that the reading the laser power meter and
digital volt meter satisfy the specified value.
Specified Value :
Laser power meter reading : 7.0 ± 0.2 mW
Digital voltmeter reading : Optical pick-up displayed value ± 10%
(Optical pick-up label)
5. Press the MENU/NO button and display “LDPWR CHECK”
and stop the laser emission.
(The MENU/NO button is effective at all times to stop the
laser emission.)
(For details of the method for checking
this value, refer to “5-8. Recording and
Displaying IOP Information”.)
5-6-3. Traverse Check
Connection :
Checking Procedure:
1. Connect an oscilloscope to CN110 pin
3
(TE) and CN110 pin
1
(VC) of the BD board.
2. Load a disc (any available on the market). (Refer to Note 1.)
3. Press the
)
/
±
button and move the optical pick-up out-
side the pit.
4. Rotate the – ˜ + knob and display “EF MO CHECK”.
5. Press the ENTER/YES button and 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 rotate the – ˜ + knob.
(Read power traverse checking)
(Traverse Waveform)
7. Press the ENTER/YES button and display “EFB = MO-W”.
8. Observe the waveform of the oscilloscope, and check that the
specified value is satisfied. Do not rotate the – ˜ + knob.
(Write power traverse checking)
(Traverse Waveform)
9. Press the ENTER/YES button display “EFB = MO-P”.
Then, the optical pick-up moves to the pit area automatically
and servo is imposed.
Note 1: After step 4, each time the ENTER/YES button is pressed,
the display will be switched between “LD 0.7 mW $ ”,
“LD 6.2 mW $ ”, and “LD Wp $ ”. Nothing
needs to be performed here.
Laser power
meter
Optical pick-up
objective lens
Digital volt meter
BD board
CN110 pin
5
(I+3V)
CN110 pin
4
(IOP)
V : 0.5 V/div
H : 10 ms/div
Input : DC mode
Oscilloscope
BD board
CN110 pin
3
(TE)
CN110 pin
1
(VC)
VC
A
B
Specified value : Below 10% offset value
Offset value (%) = X 100
I
A – B
I
2 (A + B)
VC
A
B
Specified value : Below 10% offset value
Offset value (%) = X 100
I
A – B
I
2 (A + B)