95
1
3
4
1
3
4
C
D
F
A
B
E
XV-DV820, XV-DV620
7.1.5 PROTECTION CIRCUIT
R108
27k
R3639
27k
R5559
270k
R3601
1.8k
R3607
0.1
R3603
33k
AMP Assy
CONTROL
Assy
POWER Assy
+5V
VD+5
V+5D
V+B
Q3639
Q3640
FL
RYF
RYR
B2
E2
C2
B
C
E
B
E
C
GND FL
D3601
D3603
DAP202K
to XPROTECT
to XPROTECT
µ
-com
to SP Relay Circuit
to SP Relay Circuit
to HP MUTE
DAN202K
D3635
R3641
10k
R3642
1k
R3633
10k
R3634
R3631
4.7k
R3632
4.7k
D3634
Q3632
Q3631
Q3635
Q3636
Q3633
A
B
B
Q3601
AMP Assy
R108
27k
R101
(R104)
1k
C101
(C102)
1/50
Q102
(Q104)
Q101
(Q103)
D101
(D102)
D105
(D106)
UDZS7.5B
Q101
(Q103)
C2
E2
B2
E2
C2
B2
C
E
B
E
C
B
Q102
(Q104)
R102
(R105)
10k
R103
(R106)
10k
A
B
V+5D
VD+5
VH+
(VP+15)
VH–
(VA–12)
C3633
10/50
POWER Assy
Note: • Check the Protection Circuit when the GREEN LED of DISPLAY ASSY blinks.
• When the protection circuit operates, even if the AC plug is pulled out and plugged in again, the unit will be reset for 60
seconds.
• Refer to the Schematic Diagram about the actual circuit.
(The
&
number corresponds to the marked circuits.)
At normal state, Q3601 does not operate because the speaker (6
Ω
) is
connected between FL-GNDFL and
A
point voltage is higher than
B
point.
When the register value between FL-GNDFL becomes under 1.83
Ω
,
Q3601 began to operate, Q3639 turns ON and Q3640 (E, C, B) turns
ON, then XPROTECT becomes Mid level.
→
U-com detects the XPROTECT level and sets Power OFF.
point is DC voltage by half-wave rectifying of POWER AC.
is divided by R3633 and R3634 and it
becomes Q3631 base bias voltage.
As the voltage of this point at normal state is (-) side, Q3631 does
not turn ON.
When the AC plug is pulled out and AC Power turns OFF, Q3631
base bias voltage becomes (+) side (Over 0.6V) and Q3631 turns
ON.
And it operates following procedure.
¶
At normal state as Q101 (E2, B2, C2)(Q103), Q102 (E2, B2, C2)
(Q104) is ON state,
A
point is about 5V. And because
B
point
voltage is also almost same and Q101 (E, C, B) (Q103) do not turn
ON, and Q102(E, C, B) do not turn ON.
(1) When VH+(VP+15) is short-circuited (to GND)
B
point voltage becomes almost GND level and turned to be opera-
ting point for Q101(E, C, B)(Q103), then Q101(E, C, B)(Q103)
turns ON and also Q102(E, C, B)(Q104) turns ON and XPROTECT
becomes LOW level.
→
U-com detects the XPROTECT level and sets Power OFF.
(2) When VH–(VA–12) is short-circuited
AS V
E
of Q102 (E2, C2, B2)(Q104) becomes same voltage with
V
B
, Q102(E2, C2, B2) (Q104) turns OFF.
And Q101 (E2, B2, C2)(Q103) becomes OFF, and as the voltage of
A
and
B
points is not 5V, Q101 (E, C, B)(Q103) turns ON and
it becomes same with VH+ procedure.
(3) When VD+5 is short-circuited
The line voltage of XPROTECT becomes Low level, then U-com
detects and set the POWER OFF.
(1) SP Relay
Q3632 (E2, C2, B2), Q3633, Q3636(E,C,B) becomes ON and the
line which operate SP relay becomes low level, then SP relay turns
OFF.
(2) HP MUTE
Q3635 turns ON and MUTE circuit of HP ASSY turns ON.
1
Protection Circuit when the SP terminal is overload
3
Short Circuit Detection Circuit of AMP Power Line
(+15V(VP+15), Vb+5, -12V(VA-12))
2
AC Detection Circuit
The Circuit for making POWER OFF when VP+15, VD+5 and
VA-12 is short-circuited (to GND).
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