Denon DVD-3800 Service Manual page 3

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Iop Measurement Method (Diagnostics of Traverse Unit)
Diagnostics of optical pickup (Replacing Traverse Unit) as shown as below.
1. Arrange of Judgment
(1) Check read discs
Disc no read, unsteady playback, etc.
(2) Laser current (Iop) check
Check the Iop (Laser drive current).
If the present Iop value exceeds +50% of the initial value,
replace the Traverse Unit with a new one.
(3) Replacing the Traverse Unit
Traverse Unit replacing (See page 8 and 9).
No mechanical adjustment is necessary after the replacement.
2. Iop Measurement Method
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(1) DVD laser current measurement
• Playback the title 1/chapter 1 of DVD test disc (DVDT-S01) or the equivalent.
• Connect the oscilloscope to the above mentioned point.
• DVD laser current = Measured Voltage Value / 39 (Resistance Value)
.
(2) CD laser current measurement
• Playback the track 1 of CD test disc (TCD-784) or the equivalent.
• Connect the oscilloscope to the above mentioned point.
• CD laser current value = Measured Voltage Value / 39 (Resistance Value)
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DVD laser drive current measuring points
14 1
28
15
1 8
4 5
60
41
40
61
21
80
1
1 20
24
40
1
CD laser drive current measuring points
[CD] IOP silk point
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2 9
8
Nearby C532
17
18
28
29
32 17
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1 3 6 7 16 1 3 1 5
15 1
40
1
21
20 21
20
75 51
50
76
11
26
1
100
12 48
1 25
24 37
25 36
GU-3389 P.W.B. (foil side)
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9 4 2 8
mA
DVD
mA
CD
Laser current initial value
7
6
1
40
39
0 5 8 2 9 9 4
8 14
7 1
m
DVD-3800
9 9
2 8 9 9
3