Circuit Description - Pioneer SC-65 Service Manual

5

5.2 CIRCUIT DESCRIPTION

[1] Protection Circuit Process List
Amplifier Circuit
Item Purpose
Detects MOS FET
Overheat
temperature of amplifier output
detection
stage
DC Detects DC of amplifier output
(After LPF)
detection
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
Amplifier
Detects abnormal in the
Power
Amplifier Power Supply
Supply
failure
detection
[How to Enter Release Mode]
During Standby mode, simultaneously press and hold the "TUNE [] " and "MULTI-ZONE ON/OFF" keys
for 5 seconds.
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Detection Method
Detects when TEMPERR PORT
becomes "L" in case of the
detecting temperature exceeds
95°C or rapid change by short
cuicuit of speaker terminals.
(IC3001 72pin)
Detects when MAXTEMP port
becomes below 1.9V at NTC
Thermistor detect circuit.
(IC3001 2pin)
Detects when SP output exceeds
DC ± 7V and DCERR port
becomes "L". (IC3001 80pin)
Detects when FANDET port
becomes "L". (IC3001 87pin)
Detects OLERR port becomes "L".
(IC3001 71pin)
Detects OLERR port becomes "L".
(IC3001 71pin)
Detects B-Power Supply Voltage
exceeds ± 75V or falls below ± 20V
and BERR port becomes "L".
(IC3001 84pin)
SC-65
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Status of Equipment Warning Indication
Flashes "OVERHEAT"
Shuts down when Blinks FL OFF LED
indicator.
abnormality continues for
more than 3 seconds.
Fan rotates by power-on.
MUTE on and Speaker
Relay off.
Flashes "AMP ERR". Blinks ADVANCED
Shuts down when MCACC LED
abnormality continues for
more than 3 seconds.
MUTE on and Speaker
Relay off.
Blinks FL OFF LED
Flashes "AMP ERR".
Shuts down when indicator.
abnormality continues for
more than 3 seconds.
Flashes "FAN STOP"
Shuts down when
Blinks iPod iPhone iPad
abnormality continues for
LED
more than 3 seconds.
Blinks iPod iPhone iPad
Shuts down
LED
Blinks iPod iPhone iPad
Shuts down
LED
Blinks ADVANCED
Shuts down
MCACC LED
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A
Remarks
Recoverable by power-on
after shutdown in one
minute.
MAXTEMP voltage
5V-1.8V : FANLOW
1.8V or less : FANHIGH
B
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.
C
Recoverable by power-on
Recoverable by power-on
Recoverable by power-on
D
Recoverable by only DC
DETECT cancel.
Refer to "How to Enter
Release Mode" .
E
F
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