Pioneer XV-EV9 Service Manual page 118

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Protection circuit that activates against a DVD PRTECT error
6 The DVDM monitors the voltage of the main power supply by VDET signals.
A
In Normal mode, the VDET signal is at the MID level (3.3 V). In the following conditions, the VDET signal level becomes L or H, and
the microcomputer is notified of this abnormality.
V+12
R851
47K
R852
15K
R853
10K
GNDD
V+12
B
R823
V+SR5 V+5V
15K
2SA1576A(RS)
D861
R824
R822
10K
47K
D862
D852
GNDD
Items to be detected by VDET
(1) When the power voltages inside the DVDM become abnormal, as shown in the table below
C
Status
In Normal mode
TE
L 13942296513
When an abnormality is generat
D
(2) When the VDET signal to the microcomputer is interrupted because of defective soldering of the 27-pin connector or incomplete
insertion of FFC
→ The VDET level is lowered by the pull-down resistor (1 Mohms) on the side of the microcomputer.
E
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V+5V VPR+8
V+12
R881
47K
R882
10K
R801
STBY
V+3R3
GNDD
Q821
R821
Q801
DTC124EUA
R821
10K
GNDD
Power Voltage
<8.8V
VDVD+12
>15.5V
<5.2V
VPR+8
>12.6V
V+6R5 <3V
<3.6V
V+5
>6.6V
<2.5V
V+3R3
>4.25V
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3
8
B
DVDM Assy
NORMAL : 3.3V
<
ABNORMAL : 0.5VDD
>
0.85VDD
R801
470
4
VDET
Operation
VDET voltage
Q881 Q851 Q821 Q801
off off off off
Q Q
3 6 7 1 3
on on off on
off off on on
−
off on on
− −
on on
− −
on on
−
off on on
−
on off on
− − − −
− − − −
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XV-EV9
3
4
2 9 9 4 2 8
C
MAIN Assy
R5517
220
4
VDET
µcom
17
C5619
IC5501
0.01
R5619
PDC139B
1M
PDC138A
<
L 2.5VDD
>
H 4.25VDD
Mid 3.3V
1 5 0 5 8 2 9 9 4
L
L
L
L
L
L
L
L
H
m
co
4
9 9
2 8 9 9