Pioneer XV-HTD330 Service Manual page 116

1
4 When DC is generated at the output because of
QQ
Protection circuit that activates against a DVD PRTECT error
3 7 63 1515 0
a failure in the AMP system, etc.
6 The DVDM monitors the voltage of the main power supply by VDET signals.
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
A
microcomputer is notified of this abnormality.
R3605
(R3625)
(R3615)
27k
Front L ch
V+12 V+5
(SW, SL)
47k
Front R ch
10k
(C, SR)
4.7k
R3606
+
Q924
R3638
(R3626)
10k
(R3616)
10k
27k
B • In Normal mode, both Q3637 and Q3638 are off.
(1) When positive (+) DC voltage is generated at the SP
V+6 V+5
terminal
When positive (+) DC voltage is generated at the L or R channel,
and VB of Q3637 becomes higher than that at the operation point,
Q3632 (E, C, B) is turned on, and the level of XPROTECT
becomes low.
→ The microcomputer detects the XPROTECT level and shuts
Items to be detected by VDET the power to the unit off.
(1) When the power voltages inside the DVDM become abnormal, as shown in the table below
(2) When negative (-) DC voltage was generated at the SP
C
terminal
Status
Q3638 is turned on, and XPROTECT is activated.
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 30-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.
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6CH AMP
G J
AF Assy
Assy
VD+5
+5V
R108
Q3632 27k
E
B
V+12 VPR+8
XPROTECT
47k
C
Q3637
0
10k
Q923
C3632
Q3633
Q3638
470/6.3
Q922
V+12
Q925
10k
Q926
10k
47k
Power Voltage
<1V
VDVD+12
>15.5V
<5.2V
VPR+8
>12.6V
V+6 <3V
<3.6V
V+5
>6.6V
<2.5V
V+3R3
>4.25V
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5 When abnormally high temperature is detected
by the thermistor
5 -1 IC81 abnormal temperature detection circuit
IC81
E
DVDM Assy
V+12
Q921
D922
The voltage at Point A becomes the divided voltage of TH111
V+3R3
and R111//R112 (combined resistance of parallel-connected
resistors R111 and R112.) In Normal mode, the resistance at
470 470
TH111 is much higher than R111//R112, and Q111 is off. (Note
that the resistance at TH111 becomes lower as the temperature
D921
increases.) If the solder temperature at IC81 increases abnormally,
0.1
UDZS4.7B
the temperature at TH111 (thermistor) mounted closest to the land
of IC81 increases accordingly, and the resistance at TH111
decreases.
When the temperature at TH111 reaches 90-110_C (varying
according to conditions,) the voltage at Point (A) becomes high
enough to turn Q111 on, and the level of the XPROTECT line
becomes low. The microcomputer detects the XPROTECT level
and shuts the power to the unit off.
Operation
Q923 Q924 Q922 Q921
5 -2 D22 abnormal temperature detection circuit
off off off off
If the solder temperature at D22 becomes abnormally high
(on) (on) (on) (off)
Q Q
because of short-circuiting between AC - and +, or AC - and -, this
3 6 7
off off off off
protection circuit is activated.
−
off off off
−
on on on
D22
− − − −
−
off off off
−
on on on
− − − −
− − − −
The voltage at Point A becomes the divided voltage of TH131
and R131//R132 (combined resistance of parallel-connected
resistors R131 and R132.) In Normal mode, the resistance at
TH131 is much higher than R131//R132, and Q131 is off. (Note
that the resistance at TH131 becomes lower as the temperature
increases.) If the solder temperature at D22 increases abnormally,
the temperature at TH131 (thermistor) mounted closest to the land
of D22 increases accordingly, and the resistance at TH131
decreases.
When the temperature at TH131 reaches 107-125_C (varying
according to conditions,) the voltage at Point (A) becomes high
enough to turn Q131 on, and the level of the XPROTECT line
becomes low. The microcomputer detects the XPROTECT level
and shuts the power to the unit off.
u163
y
XV-HTD330
3
2 9 9 4
8
VD+5
TH111
NCP18WF104J03RB
G
AF Assy
to
XPROTECT
A R113
220
Q111
2SC4081
R111 R112
1k 1k
VDET
µcom
1M
0.01
D921 D922 Q926 Q925
off off off off
off on off off
1 3 1 5 0 5 8 2 9
off off on on
−
off on on
−
VFL+5
on off off
− −
on on
TH131
NCP18WF104J03RB
−
to
off on on
XPROTECT
A R133
−
on off off
220
Q131
2SC4081
− − − −
R131 R132
680
560
− − −
(on)
1% 1%
m
co
.
4
2 8
9 9
VDET voltage
Mid
L
9 4 2 8 9 9
L
L
H
L
L
H
L
H
4