Sony MDS-JB920 User Manual download pdf (Page 8)

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Checks Prior to Parts Replacement and Adjustments

Before performing repairs, perform the following checks to determine the faulty locations up to a certain extent.

Details of the procedures are described in “5 Electrical Adjustments”.

• 0.9 mW power

Specified value : 0.84 to 0.92 mW

• 7.0 mW power

Specified value : 6.8 to 7.2 mW

lop (at 7mW)

• Labeled on the optical pickup

Iop value ± 10mA

• Traverse waveform

Specified value : Below 10% offset

• Error rate check

Specified value : For points a, b, and c

C1 error : Below 220

AD error : Below 2

• Error rate check

Specified value:

a. When using test disc (MDW-74/AU-1)

C1 error : Below 80

AD error : Below 2

b. When using check disc (TDYS-1)

C1 error : Below 50

• CPLAY error rate check

Specified value:

C1 error : Below 80

AD error : Below 2

• Unsatisfactory if displayed as T=@@ (##) [NG”

(@@, ## are both arbitrary numbers)

Laser power check

(5-6-2 : See page 25)

Traverse check

(5-6-3 : See page 25)

Focus bias check

(5-6-4 : See page 26)

C PLAY check

(5-6-5 : See page 26)

Self-recording/playback

check

(REC/PLAY)

(5-6-6 : See page 26)

TEMP check

(Temperature

compensation

offset check)

(5-6-1 : See page 25)

Criteria for Determination

(Unsatisfactory if specified value is not satisfied)

• Clean the optical pick-up

• Adjust again

• Replace the optical pick-up

If always unsatisfactory:

• Replace the overwrite head

• Check for disconnection of the circuits around the

overwrite head

If occasionally unsatisfactory:

• Check if the overwrite head is distorted

• Check the mechanism around the sled

• Check for disconnection of the circuits around

D101 (BD board)

• Check the signals around IC101, IC121, CN102,

CN103 (BD board)

Measure if unsatisfactory:

Note:

The criteria for determination above is intended merely to determine if satisfactory or not, and does not serve as the specified value for adjustments.

When performing adjustments, use the specified values for adjustments.

Forced Reset

The system microprocessor can be reset in the following procedure.

Use these procedure when the unit cannot be operated normally due to the overrunning of the microprocessor, etc.

Procedure :

Disconnect the power plug, short-circuit jumper wire of JW705 and JW706 (RESET).

[BAT BOARD] (Component Side)

JW706

JW705

CN703

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Sony MDS-JB920 User Manual Page 8

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