Circuit Description - Pioneer VSX-1018AH-K Service Manual

5

5.2 CIRCUIT DESCRIPTION

[1] Protection Circuit Process List
Item Purpose
To detect amplifier damage
(defect status)
A process to protect speakers
DC
(for protection of connected
detection
external devices)
To detect overloading
AMP
(abnormal status)
overload
With low-load driving or a
short circuit of the speaker
terminals (for protection of the
amplifier)
Overheat
Self reset type protection
detection
feature by temperature-rise of
heat sink
12V
To detect the shortcircuit of
trigger
12V trigger output (load more
failure
than 50mA) (for protection of
detection
the amplifier)
DC Detection Circuit
R
POWER AMP ASSY
+VL
Q5301
DC DETECTOR
R5341
OUTPUT
R ch
R5342
Q5302
SR ch
-VL
SBR ch
+DC detection: Q5741 base is "H".
–> Collector of Q5741 and Q5742 are "L".
-DC detection: Q5742 emitter is minus to the base.
–> Collector of Q5741 and Q5742 are "L".
5
6
Detection Method
Detects when the DC_PROTECT
port becomes "L".
(Pin 103 of IC101)
Detects when the OL_DET port
becomes "L" (checks by interrupt).
(Pin 26 of IC101)
Detects when the TEMP2 port
becomes "H" .
(Pin 24 of IC3004)
Detects when the 12VDET port
decoms "H".
(Pin 122 of IC101)
V+5UM
CN5803
-11
Q5741
R5744
Q5742
GAMP
R5441
R5442
R5541
R5542
C ch
VSX-LX51
6
7
Process Warning Indication
Turns muting on and
speaker relay off, then
Flashing "AMP ERR" for
turns off the power after 3
3 seconds.
seconds. Then flashes
MCACC indicator.
Turns muting on and
speaker relay off, and
None
immediately turns off the
power. Then flashes
PHASE CONTROL
indicator.
Turns muting on and
speaker relay off, then
Flashing "OVERHEAT"
turns off the power after 3
for 3 seconds.
seconds.
Turns 12V trigger output
Flashing "12V TRG ERR"
to off.
INTERFACE
E
B
ASSY
V+5UM
CN108
CN4808 CN4803
-11
-11 -11
GNDU
L ch SL ch SBL ch
7
8
Remarks
Once detected and turned
the power off, input a key
never again. If the
DC_DET port becomes
"H" within 3 seconds, the
unit returns to normal
condition automatically.
If the TEMP2 port
becomes "L" within 3
seconds, the unit returns
to normal condition
automatically.
Continue showing
warning.
Release the FL indication
by switching the INPUT
SEL or the turns the power
off.
MAIN ASSY
UCOM
Normal: High (5V)
DC det: Low (0V)
IC101
103
8
A
B
C
D
E
F
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