50
SC-27
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".
(IC
8
001
8
5pin)
Flashes "O
V
ERHEAT".
Shuts down at
continuation for more
than 3 seconds.
LED indicator continues
blinking.
Blinks STA
N
DBY/O
N
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 3
8V
and BERR port becomes "L".
(IC
8
001
8
4pin)
Shuts down
Blinks AD
V
A
N
CED
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 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.
(IC
8
001 72pin)
Shuts down.
Blinks STA
N
DBY/O
N
LED indicator.
Recoverable by power-on
1minute after shutdown
FA
N
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
N
TC
Thermistor detect circuit.
(IC
8
001 2pin)
Fan rotates below 3.1
V
.
DC
detection
Detects DC of amplifier output
(After LPF)
Detects when SP output exceeds
DC ± 7
V
and DCERR port
becomes "L". (IC
8
001
8
0pin)
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 AD
V
A
N
CED
MCACC LED
Blinks STA
N
DBY/O
N
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 FA
N
DET port
becomes "L". (IC
8
001
8
7pin)
Flashes "FA
N
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".
(IC
8
001 71pin)
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".
(IC
8
001 71pin)
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".
(IC
8
001 71pin)
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.