Circuit Description - Pioneer SC-LX85 Service Manual

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5.2 CIRCUIT DESCRIPTION

[1] Protection Circuit Process List
A
Amplifier Circuit
Item Purpose
Detects MOS FET
Overheat
temperature of amplifier output
detection
stage
B
DC Detects DC of amplifier output
(After LPF)
detection
C
Fan Detects a Fan not rotating by
loose connector or Fan lock
abnormality
when controling the Fan rotation
detection
Protects overcurrent by Zobel
Zobel Resistance when high power
output of higher frequency
detection
continued
Protects overcurrent of MOS
Overcurrent
FET in output stage when
detection overcurrent flows at the output
stage
D
Amplifier
Detects abnormal in the
Power
Amplifier Power Supply
Supply
failure
detection
E
[How to Enter Release Mode]
During Standby mode, simultaneously press and hold the "TUNE [] " and "MULTI-ZONE ON/OFF" keys
for 5 seconds.
F
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2
Detection Method
Detects when TEMPERR PORT
Flashes "OVERHEAT"
becomes "L" in case of the
Shuts down when
detecting temperature exceeds
abnormality continues for
95°C or rapid change by short
more than 3 seconds.
cuicuit of speaker terminals.
(IC3001 72pin)
Detects when MAXTEMP port
becomes below 1.9V at NTC
Fan rotates by power-on.
Thermistor detect circuit.
(IC3001 2pin)
MUTE on and Speaker
Relay off.
Flashes "AMP ERR".
Shuts down when
abnormality continues for
more than 3 seconds.
Detects when SP output exceeds
DC ± 7V and DCERR port
becomes "L". (IC3001 80pin)
MUTE on and Speaker
Relay off.
Flashes "AMP ERR".
Shuts down when
abnormality continues for
more than 3 seconds.
Flashes "FAN STOP"
Shuts down when
Detects when FANDET port
abnormality continues for
becomes "L". (IC3001 87pin)
more than 3 seconds.
Detects OLERR port becomes "L".
Shuts down
(IC3001 71pin)
Detects OLERR port becomes "L".
Shuts down
(IC3001 71pin)
Detects B-Power Supply Voltage
exceeds ± 75V or falls below ± 20V
Shuts down
and BERR port becomes "L".
(IC3001 84pin)
SC-57
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3
Status of Equipment Warning Indication
Blinks FL OFF LED
indicator.
Blinks ADVANCED
MCACC LED
Blinks FL OFF LED
indicator.
Blinks iPod iPhone iPad
LED
Blinks iPod iPhone iPad
LED
Blinks iPod iPhone iPad
LED
Blinks ADVANCED
MCACC LED
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4
Remarks
Recoverable by power-on
after shutdown in one
minute.
MAXTEMP voltage
5V-1.8V : FANLOW
1.8V or less : FANHIGH
In case of detecting DC
abnormality during
power-on sequence after
the DC was once detected.
Recoverable by only DC
DETECT cancel.
Refer to "How to Enter
Release Mode" .
In case of detecting DC
abnormality during normal
operation. Recoverable by
power-on after 1 minute.
Recoverable by power-on
Recoverable by power-on
Recoverable by power-on
Recoverable by only DC
DETECT cancel.
Refer to "How to Enter
Release Mode" .
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