MDS-NT1 - Sony Audio Service Manual (repair manual). Page 29

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This test mode performs CREC and CPLAY automatically for
mainly checking the characteristics of the optical pick-up. To
perform this test mode, the laser power must first be checked.
Perform Auto Check after the laser power check and Iop compare.

Procedure:
1. Click the 

[ENTER/YES]

. If “LDPWR                    ” is displayed,

it means that the laser power check has not been performed. In
this case, perform the laser power check and Iop compare, and
then repeat from step 1.

2. If a disc is in the mechanical deck, it will be ejected forcibly.

“DISC IN” will be displayed in this case. Load a test disc (MDW-
74/GA-1) which can be recorded.

3. If a disk is loaded at step 2, the check will start automatically.
4. When  “XX CHECK” is displayed, the item corresponding to

XX will be performed.
When “06 CHECK” completes, the disc loaded at step 2 will be
ejected. “DISC IN” will be displayed. Load the check disc (MD)
TDYS-1.

5. When the disc is loaded, the check will automatically be resumed

from “07 CHECK”.

6. After completing to test item “12 check”, check OK or NG will

be displayed. If all items are OK, “CHECK ALL OK” will be
displayed. If any item is NG, it will be displayed as “NG:xxxx”.

When “CHECK ALL OK” is displayed, it means that the optical
pick-up is normal. Check the operations of the other spindle motor,
sled motor, etc.
When displayed as “NG:xxxx”, it means that the optical pick-up
is faulty. In this case, replace the optical pick-up.

All the following checks are performed by the Auto Check mode.
They therefore need not be performed in normal operation.
5-7-6. Traverse Check
5-7-7. Focus Bias Check
5-7-8. C PLAY Check
5-7-9. Self-Recording/Playback Check

Checking Procedure:
1. Connect an oscilloscope to CN105 pin 4 (TE) and CN105

pin 6 (VC) on the BD (MD) board.

2. Load a disc (any available on the market). (Refer to Note 1)
3. Click the 

[FF]

 to move the optical pick-up outside the pit and

click the 

[STOP]

 to stop.

4. Click the 

[JOG UP]

  or 

[JOG DOWN]

 to display “EF MO

CHECK”(C14).

5. Click the 

[ENTER/YES]

 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 click the 

[JOG UP]

    or

[JOG DOWN]

.

(Read power traverse checking)

Traverse Waveform

7. Click the 

[ENTER/YES]

 to display “EFB = 

 MO-W”.

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

specified value is satisfied. Do not click the 

[JOG UP]

    or

[JOG DOWN]

.

(Write power traverse checking)

Traverse Waveform

+
–

oscilloscope

(DC range)

V: 0.1 V/div
H: 10 ms/div

BD board

CN105 pin 

4

 (TE)

CN105 pin 

6

 (VC)

Data will be erased during MO reading if a recorded disc is
used in this adjustment.

If the traverse waveform is not clear, connect the oscilloscope
as shown in the following figure so that it can be seen more
clearly.

+
–

oscilloscope

(DC range)

10 pF

330 k 

Ω

CN105 pin 

4

 (TE)

CN105 pin 

6

 (VC)

BD board

A

B

VC

Specified value : Below 10% offset value

Offset value (%) =                  X 100  

I 

A – B 

I

2 (A + B)

A

B

VC

Specified value : Below 10% offset value

Offset value (%) =                  X 100  

I 

A – B 

I

2 (A + B)