MDS-JB940 - Sony Audio Service Manual (repair manual). Page 25

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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)