Pioneer XV-EV61 Service Manual page 131

5
Protection circuit that activates against a POW ERR error
2 When the main power supply becomes LO level
because of short-circuit or disconnection of
connectors
2 -1 Short-circuit-detection circuit for the amplifier
power circuit (+15 V[VP+15], VD+5, -12 V [VA-12])
Circuit for shutting the power off when VP+15, VD+5, or VA-12
is short-circuited to ground (GND)
M VD+5
MOD. AMP Assy
E
VD+5
Q101_1/2
(Q103_1/2)
R108
C
R101
27k
to
(R104)
XPROTECT
1k
C
(µ-com) B
Q102_1/2
(Q104_1/2)
+
C101
E
(C102)
1/50
• In Normal mode, as Q101 (Q103) (E2, B2, C2) and Q102
(Q104) (E2, B2, C2) are on, the voltage at Point A is about 5 V.
The voltage at Point B is therefore about the same. As Q101
(Q103) (E, C, B) is off, Q102 (Q104) (E, C, B) is also off.
(1) When VH+(VP+15) is short-circuited to GND
As the voltage at Point B becomes almost ground potential, and
Q101 (Q103) (E, C, B) then Q102 (Q104) (E, C, B) are turned on,
the level of XPROTECT becomes low.
→ The microcomputer detects the XPROTECT level and shuts
the power to the unit off.
(2) When VH-(VA-12) is short-circuited
As the electric potential of VE at Q102 (Q104) (E2, C2, B2)
becomes the same as that at VB, Q102 (Q104) (E2, C2, B2) is
turned off. Following this, Q101 (Q103) (E2, B2, C2) is turned
off, which changes the voltage at Points A and B to a value other
than 5 V. Therefore, Q101 (Q103) (E, C, B) then Q102 (Q104) (E,
C, B) are turned on, the level of XPROTECT becomes low.
(3) When VD+5 is short-circuited
The level of the XPROTECT line becomes low. The
microcomputer detects the XPROTECT level and shuts the power
to the unit off.
2 -2 Short-circuit-detection circuit for the DVD power
supply (VP+8)
M
MOD. AMP Assy
VD+5
XPROTECT
DTA124EUA
TUNER
As the TUNER line is fixed to GND level, Q107 is always on. If
the level at VP+8 falls to GND level because of short-circuit, etc.,
Q106 is turned 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
6
VH+
(VP+15)
Q101_2/2
(Q103_2/2)
E2
D101
(D102) Q102_2/2
B2
(Q104_2/2)
B
B
C2
B2
C2
R102
(R105)
E2
10k
R109
R103
A 820
(R106)
D105
10k
(D106)
VH–
(VA–12)
VP+8
R108 D104
27k
1SS355
Q106
DTC124EUA
Q107
6
7
2 -3 Checking for VA+12 or VM+12 is short to Gnd or
Not.
E
IF/AF Assy
DVD+12
VD+12
+
GNDM
D8701
to
XPROTECT
(µ-com)
If VFDP is short-circuited to GND, or if the DC electric potential
at FL AC1 becomes GND level (in Normal mode: about -27 V)
because of a failure in the DC bias circuit of FL AC1, Q107 then
Q115 are turned on, and the level of XPROTECT becomes low.
→ The microcomputer detects the XPROTECT level and shuts
the power to the unit off.
3 When the FAN connector is disconnected or
when rotation of the fan is interrupted
M
MOD. AMP Assy
VD+5
R3654
R108
27k
to
XPROTECT
(µ-com)
C2
C
B2
Q3651_2/2
RN1901
E2 E
Q3651_1/2
RN1901
If no fan is connected between FAN+ and FAN-, or when the fan
cannot rotate because of a foreign object caught in the blades, the
BASE of Q3652 becomes OPEN, and Q3652 and Q3651 (E, C,
B) are turned off. Then Q3651 (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.
XV-EV61
7
8
VA+12
VA+12 VP+15
VP+15
Q8771
2SD2012
+
D8702
VPF+15
1.8k
A
D3658
Q3652
UDZS7.5B
DTA124TK
B
R3657
R3658
+
33(1/4W)
2.2k
C3652 D3657
47/50 1SS355
D3655
1SS355
Q3654
2SD2144S
R3655
8.2k D3656
S5688G
R3656
22k
V-12F
8
A
B
C
D
FAN+
FAN–
E
F
131