Sony MDS-SP55 Service Manual page 9

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".
Criteria for Determination
(Unsatisfactory if specified value is not satisfied)
Laser power check • 0.9 mW power
(5-6-2 : See page 24)
• 7.0 mW power
• Labeled on the optical pick-up
Traverse check • Traverse waveform
(5-6-3 : See page 24)
Focus bias check • Error rate check
(5-6-4 : See page 25)
C PLAY check • Error rate check
(5-6-5 : See page 25)
Self-recording/playback • CPLAY error rate check
check
(REC/PLAY)
(5-6-6 : See page 25)
TEMP check • Unsatisfactory if displayed as T=@@ (##) [NG]
(Temperature
compensation
offset check)
(5-6-1 : See page 24)
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 :
Remove the short-pin attached to CN821, and power off or del AC cable, and then attach it again. Remove the AC code, and wait for about
five seconds, and turn on the power again, and put the short-pin.
[MAIN BOARD] (Component Side)
CN821
Specified value : 0.84 to 0.92 mW
Specified value : 6.8 to 7.2 mW
lop (at 7mW)
Iop value ± 10mA
Specified value : Below 10% offset
Specified value : For points a, b, and c
C1 error : Below 220
AD error : Below 2
Specified value:
a.When using test disc (MDW-74/GA-1)
C1 error : Below 80
AD error : Below 2
b.When using check disc (TDYS-1)
C1 error : Below 50
Specified value:
C1 error : Below 80
AD error : Below 2
NG
(@@, ## are both arbitrary numbers)
Measure if unsatisfactory:
• Clean the optical pick-up
• Adjust again
• Replace the optical pick-up
• Replace the optical pick-up
• Replace the optical pick-up
• Replace the optical pick-up
• 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)
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