Circuit Description - Pioneer SC-37 Service Manual

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5.2 CIRCUIT DESCRIPTION

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[1] Protection Circuit Process List
B REG Power Supply
Item
B REG
power Detects overheat of
supply transistor(s) in B REG power
overheat
supply circuit
detection
B REG
power Detect abnormal voltage drop
supply when B REG transistor(s)
failure becomes failure
detection
Amplifier Circuit
Item
Detects MOS FET
Overheat
temperature of amplifier output
detection
stage
TE
L 13942296513
Detects DC of amplifier output
DC
detection (After LPF)
Fan Detects a Fan not rotating by
abnormality loose connector or Fan lock
when controling the Fan rotation
detection
Protects overcurrent by Zobel
Resistance when high power
Zobel
detection output of higher frequency
continued
Protects overcurrent of MOS
Overcurrent
FET in output stage when
detection overcurrent flows at the output
stage
Low Voltage
Detects low voltage when
detection
amplifier power supply voltage
(Amplifier
(normally ± 64V) becomes
power
below ± 42V
supply)
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Low
Voltagae
Detects low voltage of modulator
detection IC power supply (normally ± 5V)
(Modulator becomes below ± 2 - 3V
IC)
.
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Purpose Detection Method
Detects when posistor detection
temperature exceeds 120°C and
BTMP port becomes "H".
(IC8001 85pin)
Detects output voltage of B REG
power circuit decreases below 38V
and BERR port becomes "L".
(IC8001 84pin)
Purpose 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.
(IC8001 72pin)
Detects when MAXTEMP port
becomes below 1.9V at NTC
Thermistor detect circuit.
(IC8001 2pin)
Detects when SP output exceeds
DC ± 7V and DCERR port
becomes "L". (IC8001 80pin)
Detects when FANDET port
becomes "L". (IC8001 87pin)
Detects OLERR port becomes "L".
(IC8001 71pin)
Detects OLERR port becomes "L".
(IC8001 71pin)
Detects OLERR port becomes "L".
(IC8001 71pin)
No micro-computer detection
x ao
y
exists.
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Status of Equipment Warning Indication
Flashes "OVERHEAT".
Shuts down at
continuation for more
than 3 seconds.
LED indicator continues
blinking.
Shuts down
Status of Equipment Warning Indication
Shuts down.
Fan rotates during the
Receiver power on.
MUTE on and Speaker
Q Q
Relay off.
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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.
Flashes "FAN STOP"
Shuts down when
abnormality continues for
more than 3 seconds.
Shuts down
Shuts down
Shuts down
No micro-computer
control but modulator IC
u163
stops by itself.
.
SC-37
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Blinks STANDBY/ON Recoverable by power-on
1minute after shut down.
LED indicator.
Recoverable by only DC
DETECT cancel.
Blinks ADVANCED
Refer to "How to Enter
MCACC LED
Release Mode" next page.
Blinks STANDBY/ON
Recoverable by power-on
LED indicator.
1minute after shutdown
FAN control
1.9V>MAXTEMP:
High rotation
In case of detecting DC
abnormality during
power-on sequence after
1 5 0 5 8 2 9 9 4
the DC was once detected.
Blinks ADVANCED
Recoverable by only DC
MCACC LED
DETECT cancel.
Refer to "How to Enter
Release Mode" next page.
In case of detecting DC
Blinks STANDBY/ON abnormality during normal
LED indicator. operation. Recoverable by
power-on after 1 minute.
Blinks PQLS LED Recoverable by power-on
Blinks iPod LED
Recoverable by power-on
Blinks iPod LED
Recoverable by power-on
Blinks iPod LED
Recoverable by power-on
m
co Recoverable by power-on
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A
Remarks
B
Remarks
C
2 8 9 9
D
E
F
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