Pioneer XV-HTD7 Service Manual page 115

5
Protection circuit that activates against a PRTCT 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)
J VD+5
6CH AMP Assy
E
VD+5
Q101_1/2
(Q103_1/2)
R108
C
R101
27k
to
(R104)
XPROTECT
C 1k
(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)
J
6CH AMP Assy
VD+5
R108
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
Q102_2/2
(D102)
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
D104
27k 1SS355
Q106
DTC124EUA
Q107
6
7
2 -3 Short-circuit-detection circuit for VFDP
J
6CH AMP Assy
VD+5
R108
27k
to
XPROTECT
(µ-com)
Q115
DTA124EUA
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
J
6CH AMP Assy
VD+5
R3654
R108
1.8k
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,
current will not flow to R3657, and Q3652 and Q3651-1/2 (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-HTD7
7
8
G
AF Assy
R114
82k
FL AC1
R112
1k
Q114
2SD2114K
R113
(VW)
220k
VA-12
VPF+15
A
D3658
Q3652
UDZS7.5B
DTA124TK
B
R3657
R3658
+
33(1/4W)
2.2k
C3652 D3657
47/50 1SS355
D3655
1SS355
Q3654
R3655 2SD2144S
8.2k D3656
S5688G
R3656
22k
V-12F
8
A
B
C
D
FAN+
FAN–
E
F
115