General Information; Diagnosis; Protection Circuit - Pioneer S-DVR9SW Service Manual

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7. GENERAL INFORMATION

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3 7 63 1515 0

7.1 DIAGNOSIS

7.1.1 PROTECTION CIRCUIT

Note: Refer to the Schematic Diagram about the actual circuit.
(The & number corresponds to the
1 Protection circuit when the Speaker terminal
becomes overloaded
R4217
R4215
1.8k 0.1
B
Q4205
R4227
33k
D4211
D4209
In Normal mode, the speaker (6 ohms) is connected between the
FL and GND FL points. Because the voltage at Point A is higher
than that at Point B, Q4205 does not operate.
If the resistance between the FL and GND FL points becomes
1.83 ohms or less, Q4205 begins to operate, Q4212 is turned on,
Q4211 (E, C, and B)is turned on, and the level of XPROTECT
TE
L 13942296513
becomes MID.
→ The microcomputer detects the XPROTECT level and
shuts the power to the unit off.
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marked circuits.)
D
C
6CH AMP Assy
POWER Assy
A
VD+5
Front L ch
R108
27k
GND FL
+5V
R4255 R5534
4.7k 270k
Q4211
C
(DVD-RW
Q4212
B
/HDD TUNER)
+
C4255
CONTROL Assy
E
10/50
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2 Short-circuit-detection circuit for the amplifier
power circuit (VH+[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)
C
6CH AMP Assy
VD+5
R108
to
XPROTECT
(µ-com)
Q102_1/2
(Q104_1/2)
to
XPROTECT
* ( )means the wiring No. of VP+15 line.
• 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.
Q Q
(2) When VH-(VA-12) is short-circuited
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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.
co
.
S-DVR9SW
7
9 4 2 8
VH+
(VP+15)
VD+5
E2
D101
E
Q101_1/2
(D102)
(Q103_1/2)
B
B
C
R101
27k C2
R102
(R104)
(R105)
C 1k
10k
B
R103
A
+
C101
(R106)
E
(C102)
10k
1/50 (D106)
0 5 8 2 9 9 4 2 8
m
7
8
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A
Q101_2/2
(Q103_2/2)
Q102_2/2
B2
(Q104_2/2)
C2
B2
E2
B
R109
820
D105
VH–
(VA–12)
C
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D
E
F
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