Protection Circuit - Pioneer XV-DV303 Service Manual

1

7.1.5 PROTECTION CIRCUIT

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
A
seconds.
• Refer to the Schematic Diagram about the actual circuit.
(The & number corresponds to the
1 Protection Circuit when the SP terminal is overload
R3607
R3601
0.1
1.8k
B
Q3601
R3603
33k
D3601
B
D3603
DAP202K
At normal state, Q3601 does not operate because the speaker (6Ω) is
connected between FL-GNDFL and A point voltage is higher than
B point.
When the register value between FL-GNDFL becomes under 1.83Ω,
C
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.
2 AC Detection Circuit
RYF
RYR
V+5D
D3635
DAN202K
V+B
D
R3631 R3632
4.7k 4.7k
B
R3633
10k
D3631
MTZJ5.1A
C3631
2.2/50
R3635
3.3k
ACB
D3622 D3633
A
• A point is DC voltage by half-wave rectifying of POWER AC.
E
• B point is about 5V.
¶ The voltage between A-B 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.
F
92
1
2
marked circuits.)
POWER Assy
A
FL
AMP Assy
VD+5
GND FL
+5V
Q3639
R3639
27k
Q3640
C
B
C3633
E
10/50
POWER Assy
to SP Relay Circuit
R3641
10k to SP Relay Circuit
R3642
1k
E2
Q3632
Q3631
Q3636
D3634
B2
C2
R3634
4.7k B
Q3635
D3636
2
3
(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.
R108
27k
3 Short Circuit Detection Circuit of AMP Power Line
(+15V(VP+15), Vb+5, -12V(VA-12))
to XPROTECT
The Circuit for making POWER OFF when VP+15, VD+5 and
R5559
VA-12 is short-circuited (to GND).
270k
CONTROL
Assy
V+5D
R108
to XPROTECT
µ-com
Q102
(Q104)
¶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.
C
Q3633
(2) When VH–(VA–12) is short-circuited
AS V of Q102 (E2, C2, B2)(Q104) becomes same voltage with
E
E
V , Q102(E2, C2, B2) (Q104) turns OFF.
B
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.
to HP MUTE
(3) When VD+5 is short-circuited
The line voltage of XPROTECT becomes Low level, then U-com
detects and set the POWER OFF.
XV-DV303
3
4
VH+
VD+5 (VP+15)
D101
E
Q101
(D102)
(Q103)
27k
B
B
R101
C
(R104)
R102
C 1k
(R105)
B
10k
A
R103
C101
E
(R106)
(C102)
10k
1/50
4
AMP Assy
Q101
(Q103)
E2
Q102
B2
(Q104)
C2
B2
C2
E2
D105
(D106)
UDZS7.5B
VH–
(VA–12)