HCU-R700
IOP MEASUREMENT METHOD
When measuring Laser drive current (Iop), playback the discs (CD, DVD) described below, measure Iop for CD Laser and
DVD Laser by the test point (LD1 - LD4) on the SERVO P.W.B.
TEST DISC : DVD / DVDT-S01 (Manufactured by ALMEDIO INC)
CD / TCD-784 (Manufactured by ALMEDIO INC) or commercially available Discs.
1. DVD Laser current measurement
LD2+
LD3LD1- Oscilloscope
LD2
(1) Connect the oscilloscope GND side to test point LD1 near R147 and oscilloscope signal side to
`LD4LD1test point LD2 near R147.
R148(2) Playback the title 1 / chapter 1 of the DVD Test Disc.
R147(3) Measure the voltage between LD1 and LD2, calculate Iop as follows.
Measurement Voltage Value
Iop =
39 (Resistance Value)
2. CD Laser current measurement
(1) Connect the oscilloscope GND side to test point LD3 near R148 and oscilloscope signal side to
Mechanism Unit bottom sidetest point LD4 near R148.
(2) Playback the track 1 of the CD Test Disc.
(3) Measure the voltage between LD3 and LD4, calculate Iop as follows.
Measurement Voltage Value
Iop =
39 (Resistance Value)
OPTICAL PICKUP DIAGNOSTICS AND REPLACEMENT
NO DISC indicated,
Playback not smooth, etc
Laser drive current check When repairing, carry out failure diagnostics by following the procedure
HF signal checkdescribed below.
Present value : If the present value of the laser drive current is 50% up to initial value, it is the point
50% up to initial valueof the pickup replacement.
In case of the pickup replacement, replace the Traverse Unit with no adjustment.
Traverse Unit replacement
The initial value is indicated on the label on back side of Mecha.
(refer to the next page)
Laser drive current check
after replacement. If the
present value is less than
80mA, write on the new
label by hand, put on the If the present value exceeds 80mA,
new label over the old label.replace the Traverse Unit with a new one.
Cause : Damaged electrostatically when replaced.
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ACEC
