Pioneer XV-HTD530 Service Manual page 116

1
Other protection circuit
AC detection circuit
This is a protection circuit that prevents popping sounds in the Speaker and Headphones output when the AC power cord is connected or
A
disconnected.
G
AF Assy
RYF
RYR
B
ACB
• The voltage at Point A is a DC voltage which has been generated by half-wave rectification on the minus side of the AC power.
• The voltage at Point B is approx. 5 V.
C
• The base voltage at Q3631 is a voltage between Points A and B divided by R3633 and R3634. As this voltage is negative (-) in Normal
mode, Q3631 is off.
When the AC power cord is disconnected and there is no AC power input, the base voltage at Q3631 becomes +0.6 V or more, and Q3631
is turned on. Then, the operations below follow.
(1) SP Relay
Q3632 (E2, C2, B2), Q3633, and Q3636 (E, C, B) are turned on, the line to activate the SP relay becomes low level, and the SP Relay is
turned off.
(2) HP MUTE
D
Q3635 is turned on, and the MUTE circuit for HP is turned on.
E
F
116
1
2
V+5D
D3635
V+B
DAN202K
R3631 R3632
R3633
Q3631
3.3k 3.3k
10k D3634
B
D3631
R3634
MTZJ5.1A
4.7k
+
C3631
R3635
2.2/50
3.3k
A
D3622 D3633
XV-HTD530
2
3
R3641
10k
R3642
1k
Q3632
E2
Q3636
B2
C2
B
Q3635
D3636
3
4
to SP Relay Circuit
to SP Relay Circuit
C
Q3633
E
to HP MUTE
4