Sony MVC-CD300 Service Manual page 68

7-1-4. LD Initial Check
Purpose:
Initialization to enable setting the read/write laser power values.
Trouble Symptom
NG is displayed.
Cause of Trouble
The write laser power control voltage VWDC (pin 6 of IC013
on the MD-083 board) has increased more than the specification
value because the front monitor output (pin ql of CN001 on
the MD-083 board) of the OP (optical device) is too low.
Remedial Measure
Replace the OP (optical device).
7-1-5. Front Monitor Gain
Purpose:
Set the maximum write power. The relationship between the write
laser power control voltage VWDC1 (pin wj of CN001 on the MD-
083 board) and the actual laser write power is adjusted.
Trouble Symptom
NG is displayed immediately after clicking the [INPUT] button when
the optical power meter measurement value is written in accordance
with the instructions that are displayed on the Write Power Adjust
screen.
Cause of Trouble
• The laser output is insufficient due to deterioration of laser
diode.
• The laser output does not corresponds to the change of the
VWDC1 voltage. The laser diode is defective.
Remedial Measure
Replace the OP (optical device).
7-2. SKEW Adjustment
7-2-1. SKEW Adjustment
Purpose:
Adjust the amount of skew error caused by the OP (optical device)
to minimum.
Trouble Symptom
No symptom is displayed. (The OK message always appears because
OK/NG judgement is not performed.)
7-3. Read (CD) Adjustment
7-3-1. Adjust FE
Purpose:
Perform this adjustment to minimize the variations in focus error
amplitude and the offset caused by the OP (optical device).
Trouble Symptom
NG is displayed.
Cause of Trouble
As the result of adjustment, variation has exceeded the
specification value.
Remedial Measure
Replace the OP (optical device).
7-3-2. DPP Balance
Note: DPP =Differential Push-Pull
Purpose:
Perform this adjustment to minimize the variations in tracking error
caused by OP (optical device).
Trouble Symptom
NG is displayed.
Cause of Trouble
As the result of adjustment, variation has exceeded the
specification value.
Remedial Measure
Replace the OP (optical device).
7-3-3. TE Gain Offset
Note: TE =Tracking error
Purpose:
Perform this adjustment to minimize the variations in the tracking
error amplitude offset caused by the OP (optical device) and IC.
Trouble Symptom
NG is displayed.
Cause of Trouble
As the result of adjustment, variation has exceeded the
specification value.
Remedial Measure
Replace the OP (optical device).
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