S-DV990SW
38
1
2
4
1
2
4
C
D
F
A
B
E
A
+
to
XPROTECT
(
µ
-com)
R108
27k
Q3651_2/2
RN1901
Q3651_1/2
RN1901
C2
C
E
B
E2
B2
VD+5
FAN+
VPF+15
V-12F
R3654
1.8k
D3658
UDZS7.5B
D3657
1SS355
D3655
1SS133
D3651-D3654
1SS133
×
4
R3655
8.2k
R3656
22k
R3658
2.2k
R3657
33(1/4W)
Q3652
DTA124TK
Q3654
2SD2144S
C3652
47/50
6CH AMP Assy
C
3
FAN detection circuit
FAN–
If no fan is connected between FAN+ and FAN-, or when the fan
cannot rotate because of a foreign object caught in the blades,
current will not flow to R3657, and Q3652 and Q3651-
1/2
(E, C,
B) are turned off. Then Q3651-
2/2
(E2, B2, C2) is turned on, and
the level of XPROTECT becomes low.
→
The microcomputer detects the XPROTECT level and shuts
the power to the unit off.
When FAN+ and FAN- are short-circuited, the electric potential at
Point
A
becomes higher than GND level by the addition of the
values at D3656 and D3657. As this value is lower than that at
D3658, Q3651 (E, C, B) is turned off, Q3651 (E2, B2, C2) is
turned on, and the level of XPROTECT becomes low.
4
DC detection circuit of SP terminal
R3357
(R3457)
18k
R3358
(R3458)
R3603
Front L ch
(SW, SL)
+5V
C3602
Q3605
Q111
2SC4081
R113
220
IC81
NJM7805FA
R112
1k
TH111
NCP18WF104J03RB
R111
1k
Q3604
Q3606
Q3607
B
C
E
+
XPROTECT
to
XPROTECT
POWER Assy
D
R108
27k
VD+5
VD+5
6CH AMP
Assy
C
6CH AMP
Assy
C
Front R ch
(C, SR)
• In Normal mode, both Q3605 and Q3604 are off.
(1) When positive (+) DC voltage is generated at the SP
When positive (+) DC voltage is generated at the L or R channel,
and VB of Q3605 becomes higher than that at the operation point,
Q3606 (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
Q3604 is turned on, and XPROTECT is activated.
5
IC81 abnormal temperature detection circuit
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.
www. xiaoyu163. com
QQ 376315150
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TEL 13942296513
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TEL 13942296513 QQ 376315150 892498299
TEL 13942296513 QQ 376315150 892498299
