DOWNLOAD Sony MDS-JB940 Service Manual ↓ Size: 12.66 MB | Pages: 74 in PDF or view online for FREE

25

These checks are performed before replacing parts to determine the
faulty locations.

When performing adjustments, set the internal temperature and room
temperature of 22 

°C to 28 °C.  Accurate checks are not possible

because the temperature of the IC and diode, etc. rises as time goes
by after the power is turned on. If the check is performed in this
state, wait for some minutes and perform the check again.

Checking Procedure:
1.

Turn the  l AMS L  knob to display “TEMP CHECK”
(C12).

2.

Press the  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)

Before checking, check the IOP value of the optical pick-up.
(Refer to 5-8. Recording and Displaying IOP Information)

Checking 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.

2.

Then, turn the  l AMS L  knob to display “LDPWR
CHECK” (C13).

3.

Press the  YES  button once to display “LD 0.9 mW $ 

”.

Check that the laser power meter satisfy the specified value.
Specified value:
Laser power meter reading: 0.84 to 0.92 mW

4.

Press the  YES  button once more to display “LD 7.0 mW $

”. Check that 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  button to display “LDPWR CHECK”
and stop the laser emission.
(The  MENU/NO  button is effective at all times to stop the
laser emission)

After step 4, each time the  YES  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.

The current IOP value when 7 mW laser power is output and the
reference IOP value (normally, the value when shipped from the
factory) written in the non-volatile memory are compared and the
degree of increase or decrease is shown as a percentage.

Do the following operation when the temperature of the optical
pick-up is almost the same as room temperature.

Operation Procedure:
1.

Turn the  l AMS L  knob to display “Iop Compare”.

2.

Press the  YES  button to start measurement.

3.

After the measurement is complete, the display changes to
“±xx% yy”.  “xx” indicates the degree of increase or decrease.
OK or NG is shown in “yy”, which indicates whether the
increase or decrease is acceptable.

4.

Press the  MENU/NO  button to end Iop Compare.

This test mode automatically performs C-REC and C-PLAY and
checks mainly the characteristics of the optical pick-up. To execute
the test mode, first check the laser power and perform AUTO
CHECK after Iop Compare.

Operation Procedure:
1.

Press the  YES  button. If “LDPWR 

 ” appears, which

means the laser power has not been checked, first check the
laser power and perform Iop Compare. Then, repeat this step.

2.

If there is a disc in the mechanism deck, the disc is forcibly
ejected. After “DISC IN” appears, load a recordable test disc
(MDW-74/GA-1).

3.

When the disc is loaded in step 2, the check automatically starts.

4.

While “XX CHECK” is displayed, the check of the item shown
in “XX” is in progress.
After “06 check” is complete, eject the disc loaded in step 2.
When “DISC IN” appears, load the TDYS-1 check disc (MD).

5.

After the disc is loaded, the check automatically restarts from
“07 CHECK”.

6.

After the check of item 12 is complete, “OK” or “NG” appears.
When all items are OK, “CHECK ALL OK” appears. If even
one of the items failed, “NG: xxxx” appears.

When “CHECK ALL OK” appears, there is no problem in the optical
pick-up, Check the operations of the spindle motor, sled motor, etc.

If “NG: xxxx” appears, there is an abnormality in the optical pick-
up. Replace the optical pick-up.

CN105 pin 1 (I +3V)
CN105 pin 2 (IOP)

KMS-260B

27X40
B0825

Ω)

26

All of the following check modes have already been checked in the
section “AUTO CHECK”. Therefore, normally do not check them.

Checking Procedure:
1.

Connect an oscilloscope to CN105 pin 4 (TE) and CN105
pin 6 (VC) on the BD board.

2.

Load a recordable disc (MDW-74/GA-1).

3.

Press the M button to move the optical pick-up outside the
pit.

4.

Turn the l AMS L knob to display “EF MO
CHECK”(C14).

5.

Press the  YES  button to display “EFB = 

 MO-R”.

6.

Observe the waveform of the oscilloscope, and check that the
specified value is satisfied. Do not turn the  l AMS L
knob.

7.

Press the  YES  button to display “EFB = 

 MO-W”.

8.

Observe the waveform of the oscilloscope, and check that the
specified value is satisfied. Do not turn the  l AMS L
knob.

9.

Press the  YES  button to display “EFB = 

 MO-P”.

Then, the optical pick-up moves to the pit area automatically
and servo is imposed.

10. Observe the waveform of the oscilloscope, and check that the

specified value is satisfied. Do not turn the  l AMS L
knob.

CN105 pin 4 (TE)
CN105 pin 6 (VC)

× 100

IA – BI

11. Press the  YES  button to display “EF MO CHECK”

The disc stops rotating automatically.

12. Press the  EJECT A button and take out the disc.
13. Load the check disc (MD) TDYS-1.
14. Turn the  l AMS L  knob and display “EF CD CHECK”

(C15).

15. Press the  YES  button to display “EFB = 

 CD”. Servo is

imposed automatically.

16. Observe the waveform of the oscilloscope, and check that the

specified value is satisfied. Do not turn the l AMS L
knob.

17. Press the  YES  button to display “EF CD CHECK”.
18. Press the  EJECT A button and take out the test disc (TDYS-

1).

2. Focus Bias Check
Change the focus bias and check the focus tolerance amount.
Checking Procedure :
1.

Load the recorded test disk (MDW-74/GA-1).
(Refer to “5-5.  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 1MID”.

4.

Press the  MENU/NO  button when “C = 

 AD = 

” is

displayed.

5.

Turn the  l AMS L  knob to display “FBIAS CHECK”
(C16).

6.

Press the  YES  button to display “

/

 c = 

”.

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 to display “

/

 b = 

”.

Check that the C1 error is about 100 and ADER is below 2.

8.

Press the  YES  button to display “

/

 a = 

”.

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 test disc.

27

a. MO Error Rate Check
Checking Procedure :
1.

Load the recorded test disk (MDW-74/GA-1).
(Refer to “5-5.  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 “C = 

 AD = 

”.

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.

b. CD Error Rate Check
Checking Procedure :
1.

Load the check disc (MD) TDYS-1.

2.

Turn the  l AMS L  knob to display “CPLAY 1 MODE”
(C34).

3.

Press the  YES  button twice to display “CPLAY 1 MID”.

4.

The display changes to “C = 

 AD = 

”.

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.

• Create a continuous recording disc using the unit to be repaired

and check the error rate.

1.

Load a recordable test disc (MDW-74/GA-1).

2.

Turn the  l AMS L  knob to display “CREC 1 MODE”
(C34).

3.

Press the  YES  button to display “CREC 1 MID”.

4.

 REC z  lights and “CREC(@@@@” (@@@@ indicates the
address.). Then recording starts.

5.

About one minute later, press the  MENU/NO  button to stop
the continuous recording.

6.

Turn the  l AMS L  knob to display “CPLAY 1 MODE”
(C34).

7.

Press the  YES  button to display “CPLAY 1 MID”.

8.

The display changes to “C1 = 

 AD = 

”.

9.

Check that the C1 error rate is below 20 and ADER is below 2.

10. Press the  MENU/NO  button to stop playback and press the

EJECT A button to remove the disc.

Mode which sets the adjustment results recorded in the non-volatile
memory to the initial setting value. However the results of the
temperature compensation offset adjustment will not change to the
initial setting value.
If initial setting is performed, perform all adjustments again
excluding the temperature compensation offset adjustment.
For details of the initial setting, refer to “5-4. Precautions for
Adjustments” and execute the initial setting before the adjustment
as required.

Setting Procedure :
1.

Turn the  l AMS L  knob to display “ADJ CLEAR”
(C28).

2.

Press the  YES  button. “Complete!” will be displayed
momentarily and initial setting will be executed, after which
“ADJ CLEAR” will be displayed.

The IOP data can be recorded in the non-volatile memory. The IOP
value on the optical pick-up label and the IOP value after the
adjustment will be recorded. Recording these data eliminates the
need to read the label on the optical pick-up.

Recording Procedure :
1.

Turn the  l AMS L  knob to display “Iop Write” (C05),
and press the  YES  button.

2.

The display becomes Ref=@@@/@ (@ is an arbitrary number)
and the numbers which can be changed will blink.

3.

Input the IOP value on the optical pick-up label.
To select the number : Turn the  l AMS L  knob.
To select the digit : Press the  l AMS L  knob

4.

When the  YES  button is pressed, the display becomes
“Measu=@@@.@” (@ is an arbitrary number).

5.

As the adjustment results are recorded for the 6 value. Leave it
as it is and press the  YES  button.

6.

“Complete!” will be displayed momentarily. The value will be
recorded in the non-volatile memory and the display will
become “Iop Write”.

Display Procedure :
1.

Turn the  l AMS L  knob to display “Iop Read”(C26).

2.

“@@.@/##.#” is displayed and the recorded contents are
displayed.
@@.@ indicates the IOP value on the optical pick-up label.
##.# indicates the IOP value after adjustment

3.

To end, press the  l AMS L  button or  MENU/NO
button to display “Iop Read”.

Save the temperature data at that time in the non-volatile memory

as 25 ˚C reference data.

1. Usually, do not perform this adjustment.

2. Perform this adjustment in an ambient temperature of 22 ˚C to

28 ˚C. Perform it immediately after the power is turned on when
the internal temperature of the unit is the same as the ambient

temperature of 22 ˚C to 28 ˚C.

3. When D101 has been replaced, perform this adjustment after

the temperature of this part has become the ambient temperature.

Adjusting Procedure :
1.

Turn the  l AMS L  knob to display “TEMP ADJUS”
(C03).

2.

Press the   YES  button to select the “TEMP ADJUS” mode.

3.

“TEMP = 

 [OK” and the current temperature data will be

displayed.

4.

To save the data, press the  YES  button.
When not saving the data, press the  MENU/NO  button.

5.

When the  YES  button is pressed, “TEMP = 

 SAVE” will be

displayed and turned back to “TEMP ADJUS” display then.
When the  MENU/NO  button is pressed, “TEMP ADJUS”
will be displayed immediately.

Specified Value :
The “TEMP =

” should be within “E0 - EF”, “F0 - FF”, “00 -

0F”,  “10 - 1F” and “20 - 2F”.

28

Check the IOP value of the optical pick-up before adjustments.
(Refer to 5-8. Recording and Displaying IOP Information)

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.

2.

Turn the  l AMS L  knob to display “LDPWR ADJUS”
(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.

6.

Turn the  l AMS L  knob so that the reading of the laser
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.

7.

Then, turn the  l AMS L  knob to display “LDPWR
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%

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).

CN105 pin 1 (I +3V)
CN105 pin 2 (IOP)

KMS-260B

27X40
B0825

Ω)

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”.

After step 4, each time the  YES  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.

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.

Perform this operation when the temperature of the optical pick-up
is almost same as the room temperature.

Operation Procedure:
1.

Turn the  l AMS L  knob to display “Iop NV Save”
(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.