62
SC-LX81
1
2
3
4
A
B
C
D
E
F
1
2
3
4
5.2 CIRCUIT DESCRIPTION
B REG Power Supply
[1] Protection Circuit Process List
Item
Purpose
Detection Method
Status of E
q
uipment
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".
(IC2001 4
8
pin)
Flashes "O
V
ERHEAT"
indicator.
Shuts down at
continuation for more
than 3 seconds.
LED indicator continues
blinking.
"O
V
ERHEAT" and 3
second flashing.
Blinks ICE blue LED
indicator.
Recoverable by power-on
B REG
power
supply
failure
detection
Detect abnormal voltage drop
when B REG transistor(s)
becomes failure
Detects output voltage of B REG
power cuicuit decreases below
3
8V
and BERR port becomes "L".
(IC2001 47pin)
Shuts down
Blinks MCACC LED
Unrecoverable
Amplifier Circuit
Item
Purpose
Detection Method
Status of E
q
uipment
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.
(IC2001
8
9pin)
Shuts down with FL
indication of "AMP
O
V
ERHEAT".
LED indicator continues
blinking.
Indicates "AMP
O
V
ERHEAT".
Blinks ICE blue LED
indicator.
Recoverable by power-on
Detects when MAXTEMP port
becomes below 3.3
V
at
N
TC
Thermistor detect circuit.
(IC2001 91pin)
Fan rotates below 3.3
V
.
DC
detection
Detects DC of amplifier output
(After LPF)
Detects when SP output exceeds
DC ± 7
V
and DCERR port
becomes "L". (IC2001 90pin)
Let MUTE on, Speater
Relay off and shuts down
3 seconds after to blink
MCACC LED.
Flashes "AMP
ERR"indicator.
Blinks MCACC LED
Let MUTE on, Speater
Relay off and shuts down
3 seconds after to blink
ICE blue indicator.
Flashes "AMP
ERR"indicator.
Blinks ICE blue 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
detecting DC.
Unrecoverable
Fan
abnormality
detection
Detects a Fan not rotating by
loose connector or Fan lock
when controling the Fan rotation
Detects when FA
N
DET port
becomes "L". (IC2001
88
pin)
Shuts down when
abnormality continues for
more than 3 seconds.
Flashes "FA
N
STOP"indicator.
Blinks Digital
V
ideo
Scaler 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".
(IC2001 17pin)
Shuts down
Shuts down
Blinks PHASE
CO
N
TROL LED
Blinks PHASE
CO
N
TROL LED
Shuts down
Blinks PHASE
CO
N
TROL LED
Overcurrent
detection
Protects overcurrent of MOS
FET in output stage when
overcurrent flows at the output
stage
Detects OLERR port becomes "L".
(IC2001 17pin)
Low
V
oltage
detection
(Amplifier
power
supply)
Detects low voltage when
amplifier power supply voltage
(normally ± 64
V
) becomes
below ± 42
V
Detects OLERR port becomes "L".
(IC2001 17pin)
AMP_Overload DET
Low
V
oltagae
detection
(Modulator
IC)
Detects low voltage of modulator
IC power supply (normally ± 5
V
)
becomes below ± 2 - 3
V
N
o micro-computer detection
exists.
N
o micro-computer
control but modulator IC
stops by itself.