Pioneer SC-LX72, Service Manual

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SC-LX82
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5.2 CIRCUIT DESCRIPTION
B REG Power Supply
[1] Protection Circuit Process List
Item Purpose Detection Method Status of Equipment Warning Indication Remarks
B REG
power
supply
overheat
detection
Detects overheat of
transistor(s) in B REG power
supply circuit
Detects when posistor detection
temperature exceeds 120°C and
BTMP port becomes "H".
(IC8001 85 pin)
Flashes "OVERHEAT".
Shuts down at
continuation for more
than 3 seconds.
LED indicator continues
blinking.
Blinks STANDBY/ON
LED indicator. Recoverable by power-on
1minute after shut down.
B REG
power
supply
failure
detection
Detect abnormal voltage drop
when B REG transistor(s)
becomes failure
Detects output voltage of B REG
power circuit decreases below 38 V
and BERR port becomes "L".
(IC8001 84 pin)
Shuts down
Blinks ADVANCED
MCACC LED
Recoveable by only DC
DETECT cancel.
Refer to “How to Enter
Release Mode” next page.
Amplifier Circuit
Item Purpose Detection Method Status of Equipment Warning Indication Remarks
Overheat
detection
Detects MOS FET
temperature of amplifier output
stage
Detects when TEMPERR PORT
becomes "L" in case of the
detecting temperature exceeds
95°C or rapid change by short
cuicuit of speaker terminals.
(IC8001 72 pin)
Shuts down.
Blinks STANDBY/ON
LED indicator.
Recoverable by power-on
1 minute after shutdown
FAN control
3.1 V > MAXTEMP >
1.9 V: Low rotation 1.9 V >
MAXTEMP: High rotation
Detects when MAXTEMP port
becomes below 3.1 V at NTC
Thermistor detect circuit.
(IC8001 2 pin)
Fan rotates below 3.1V.
DC
detection
Detects DC of amplifier output
(After LPF)
Detects when SP output exceeds
DC ± 7 V and DCERR port
becomes "L". (IC8001 80 pin)
MUTE on and Speaker
Relay off.
Flashes “AMP ERR”.
Shuts down when
abnormality continues for
more than 3 seconds.
MUTE on and Speaker
Relay off.
Flashes “AMP ERR”.
Shuts down when
abnormality continues for
more than 3 seconds.
Blinks ADVANCED
MCACC LED
Blinks STANDBY/ON
LED indicator.
In case of detecting DC
abnormality during normal
operation. Recoverable by
power-on after 1 minute.
In case of detecting DC
abnormality during
power-on sequence after
the DC was once detected.
Recoveable by only DC
DETECT cancel.
Refer to “How to Enter
Release Mode” next page.
Fan
abnormality
detection
Detects a Fan not rotating by
loose connector or Fan lock
when controling the Fan rotation
Detects when FANDET port
becomes "L". (IC8001 87 pin)
Flashes "FAN STOP"
Shuts down when
abnormality continues for
more than 3 seconds.
Blinks PQLS LED
Recoverable by power-on
Recoverable by power-on
Recoverable by power-on
Recoverable by power-on
Recoverable by power-on
Zobel
detection
Protects overcurrent by Zobel
Resistance when high power
output of higher frequency
continued
Detects OLERR port becomes "L".
(IC8001 71 pin)
Shuts down
Shuts down
Blinks PHASE
CONTROL LED
Blinks PHASE
CONTROL LED
Shuts down
Blinks PHASE
CONTROL LED
Overcurrent
detection
Protects overcurrent of MOS
FET in output stage when
overcurrent flows at the output
stage
Detects OLERR port becomes "L".
(IC8001 71 pin)
Low Voltage
detection
(Amplifier
power
supply)
Detects low voltage when
amplifier power supply voltage
(normally ± 64 V) becomes
below ± 42 V
Detects OLERR port becomes "L".
(IC8001 71 pin)
Low
Voltagae
detection
(Modulator
IC)
Detects low voltage of modulator
IC power supply (normally ± 5 V)
becomes below ± 2 to 3 V
No micro-computer detection
exists.
No micro-computer
control but modulator IC
stops by itself.