Protection Circuit - Pioneer XW-HTD630 Manual

5

7.1.4 PROTECTION CIRCUIT

PROTECT Operation Description
G
RELAY ASSY
(AWU8126)
PRE12
D3651
D3652
D3653
D3654
D3656
47K
FAN D3664
R3661
10K
33K
Q3655
DTC114TK
10
R3659
R3670
33
33
R3666
R3665
33
33
100/10
This circuit has following five items that performs the Short
detection.
1 PRE5
2 PRE12
3 FAN +B (for Hi rotation)
4 FAN short
5 FAN open
5
6
UNREG
PRE+5
1/50
D71
R76
4.7K
R3681
390
R3664
390
R3663
390
22K
C3656
47/35
D3665 390
R3657
22K
390
R3651
6
7
R73
Q71
100
470K
10/50
R74
47K
D73
D75
D74 D72
R78 R74
4.7K 4.7K
PRE5 PRE12
R3654
V+B (UNREG PRE12)
Q3651
4.7K
D3657
R3655
22
Q3652
R3656
220
D77
R3652 R3679
680 680
R3667
10K
Q3653
47K
1/50
About 1 to 3
When the voltages of 1 to 3 fell in the voltage (less than
about 3.2V) that Q71 turned ON, and turn Q3654 ON via
R73 and D75.
→ XPROTECT becomes low.
About FAN short or open detection
At normal state:
The voltage appears in Q3655 base by current that flows
to the FAN, and so Q3655 is always ON.
Q3654 cannot turn ON so that the voltage appears only with
Vce(sat) of Q3655 in D3665 anode.
In addition, Q3654 cannot turn ON so that the voltage (Vb ×
1/4.3=lesst than 0.8V) that divided the base voltage of
Q3655 with 33k and 10k is the voltage of D3664 anode.
Therefore, Q3654 maintains the OFF state.
In the short or open state:
The voltage appears at D3664 anode in the short state
and appears at D3665 anode in the open state.
Q3654 turns ON and XPROTECT becomes low (Active).
XW-HTD630
7
8
1µ
R75
10K
To
XPROTECT
H/L CONT
8
A
B
C
D
E
F
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