Pioneer XV-HTD330 Service Manual page 115

5
4 When DC is generated at the output because of
QQ
3 7 63 1515 0
a failure in the AMP system, etc.
R3605
(R3625)
(R3615)
27k
Front L ch
(SW, SL)
Front R ch
(C, SR)
R3606
R3638
(R3626)
(R3616)
27k
• 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.
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L 13942296513
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G
AF Assy
VD+5
+5V
Q3632
E
B
C
Q3637
+
C3632
Q3633
Q3638
10k 470/6.3
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6
5 When abnormally high temperature is detected
8
by the thermistor
5 -1 IC81 abnormal temperature detection circuit
6CH AMP
J
Assy
IC81
R108
27k
XPROTECT
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.
5 -2 D22 abnormal temperature detection circuit
If the solder temperature at D22 becomes abnormally high
Q Q
because of short-circuiting between AC - and +, or AC - and -, this
3 6 7 1 3
protection circuit is activated.
D22
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
.
XV-HTD330
6
7
2 9 9 4 2 8
VD+5
TH111
NCP18WF104J03RB
A R113
220
Q111
2SC4081
R111 R112
1k 1k
1 5 0 5 8 2 9 9 4
VFL+5
TH131
NCP18WF104J03RB
A R133
220
Q131
2SC4081
R131 R132
680
560
1% 1%
m
co
7
8
9 9
A
to
XPROTECT
B
C
2 8 9 9
to
XPROTECT
D
E
F
115
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