Realistic STA-95 - Page 17

NOTE:
1. This Receiver has built-in
over
load
thermal
protection
for
abnormal operation.
When the temperature of thermal
protector
(installed
with
heat
sink) does rise abnormally
(9015'C),
the
thermal
protector
will automatically cut out, and as
soon as the
temperature
goes
down suff iciently
(35115'C),
the thermal
protector
turns back
on automatically.
lf
the
Receiver
does turn itself off,
check
ventilation and
speaker connections.
r_,
t_
SWlO
r---1
Transistors TR611
and TR612
protect
audio
output stage
when abnorma
lly high
current flows
in
TR609 and
TR610 caused
by excessive
input
drive,
or too low
impedance load
is
connected at output.
lf increase
of the current is
excessive, the
voltage
across
R622
and
R623
will turn on TR611
and TR612 which are
not
normally
biased
on and
collectors
of these
transistors
(through
D602 and
D603
diodes) reduce
biases
on TR607
and
TR60B which
decreases
drive to
output
transistors
TR609 and
TR610 to reduce
the current.
This occurs
to
protect
not
only
the circuit
but also
the
speakers
against high level
switching
clicks
and
pop
noises.
POWEB TRANSFORI\1EH
T851
T SINK OF POWEB TRANSISTOBS
THEBMAL
PROTECTOR
AC
120V 6oHz
-
i
=
POWER
lj'---J
CRB5]
2.
t
=
.
6
o
F
17