XV-HTD330
116
1
2
4
1
2
4
C
D
F
A
B
E
4
When DC is generated at the output because of
a failure in the AMP system, etc.
5
When abnormally high temperature is detected
by the thermistor
R3605
(R3625)
(R3615)
27k
R3606
(R3626)
(R3616)
27k
R3638
10k
Front L ch
(SW, SL)
+5V
C3632
470/6.3
Q3637
Q111
2SC4081
R113
220
IC81
R112
1k
TH111
NCP18WF104J03RB
R111
1k
Q3638
Q3632
Q3633
B
C
E
+
XPROTECT
to
XPROTECT
AF Assy
G
R108
27k
VD+5
VD+5
6CH AMP
Assy
J
Front R ch
(C, SR)
• In Normal mode, both Q3637 and Q3638 are off.
(1) When positive (+) DC voltage is generated at the SP
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
the power to the unit off.
(2) When negative (-) DC voltage was generated at the SP
terminal
Q3638 is turned on, and XPROTECT is activated.
5
-1 IC81 abnormal temperature detection circuit
5
-2 D22 abnormal temperature detection circuit
A
Q131
2SC4081
R133
220
D22
R132
680
1%
TH131
NCP18WF104J03RB
R131
560
1%
to
XPROTECT
VFL+5
A
The voltage at Point
A
becomes the divided voltage of TH111
and R111//R112 (combined resistance of parallel-connected
resistors R111 and R112.) In Normal mode, the resistance at
TH111 is much higher than R111//R112, and Q111 is off. (Note
that the resistance at TH111 becomes lower as the temperature
increases.) If the solder temperature at IC81 increases abnormally,
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.
If the solder temperature at D22 becomes abnormally high
because of short-circuiting between AC - and +, or AC - and -, this
protection circuit is activated.
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.
Protection circuit that activates against a DVD PRTECT error
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
microcomputer is notified of this abnormality.
DVDM Assy
E
AF Assy
G
10k
10k
4.7k
47k
Q924
Q923
470
D922
Q922
Q925
D921
UDZS4.7B
Q926
Q921
V+5
V+12
470
1M
0.1
V+3R3
10k
10k
V+12
V+5
V+6
0
10k
47k
VPR+8
V+12
V+12
47k
0.01
VDET
µ
com
Items to be detected by VDET
(1) When the power voltages inside the DVDM become abnormal, as shown in the table below
(2) When the VDET signal to the microcomputer is interrupted because of defective soldering of the 30-pin connector or incomplete
The VDET level is lowered by the pull-down resistor (1 Mohms) on the side of the microcomputer.
Status Power
Voltage
Operation
VDET voltage
Q923
Q924
Q922
Q921
D921
D922
Q926
Q925
In Normal mode
off
off
off
off
off
off
off
off
Mid
When an abnormality is generat
VDVD+12
<1V
(on)
(on)
(on)
(off)
off
on
off
off
L
>15.5V
off
off
off
off
off
off
on
on
L
VPR+8
<5.2V
−
off
off
off
off
−
on
on
L
>12.6V
−
on
on
on
on
−
off
off
H
V+6
<3V
−
−
−
−
−
−
on
on
L
V+5
<3.6V
−
off
off
off
off
−
on
on
L
>6.6V
−
on
on
on
on
−
off
off
H
V+3R3
<2.5V
−
−
−
−
−
−
−
−
L
>4.25V
−
−
−
−
(on)
−
−
−
H
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