
1.
INTRODUCTION
This
service
manual
was
prepared
for
use
by
Authorized
Warranty
Stations
and
contains
service
information
for
the
Super
Scope
Model
BLA-545/A-545/BLA-530/A-530
Stereo
Console
Amplifier.
Servicing
information
and
voltage
data
included
in
this
manual
are
intended
for
use
by
knowledgeable
and
expe-
rienced
personnel
only.
All
instructions
should
be
read
carefully.
No
attempt
should
be
made
to
proceed
without
a
good
understanding
of
circuitry
operation.
The
parts
list
furnishes
complete
ordering
information.
Most
replacement
parts
should
be
ordered
from
the
Marantz
Company.
However,
a
simple
description
is
included
for
parts
which
can
be
obtained
locally.
2.
PRE-AMPLIFIER
Signals
from
the
TUNER
and
AUX
terminals
are
taken
to
the
SELECTOR
SWITCH
(SV01).
Signals
from
the
PHONO
terminals
pass
through
the
phono
amplifier
(Q401,
0403
and
Q405)
where
they
are
amplified
by
36dB
and
at
the
same
time
undergo
RIAA
equalization,
before
going
to
the
SELECTOR
SWITCH
(SV01).
The
signal
selected
by
the
selector
switch
passes
through
the
buffer
amplifier
and
then
is
led
to
the
mixing
variable
resister
RJ10.
The
signal
from
the
mic
jack
is
amplified
36dB
by
the
mic
amplifier
composed
of
QJO01
and
QJ02
and
routed
to
the
mixing
variable
resister.
These
two
signals
are
mixed
at
the
mixing
variable
resistor
and
then
led
to
the
TAPE
MONITOR
switch
and
TAPE
OUT
terminal.
Signals
which
enter
from
the
TAPE
IN
terminals
are
taken
to
the
TAPE
MONITOR
SWITCH.
Signals
which
are
selected
by
the
TAPE
MONITOR
SWITCH
are
taken
to
the
MONO
SWITCH
BALANCE
and
VOLUNE
potentiometers,
and
then
enter
the
preamp-
tifier
(QEO1
and
QE03).
The
preamplifier
has
a
gain
of
19dB
and
also
serves
as
a
tone
control
amplifier,
with
the
frequency
response
being
controlled
by
the
BASS
and
TREBLE
controls.
After
passing
through
the
preamplifier,
the
signals
enter
the
main
amplifier.
BLA-545/A-545/BLA-530/A-530
3.
MAIN
AMPLIFIER
The
main
amplifier
contains
an
NF
type
high
pass
filter
network
which
can
be
switched
in
and
out
of
circuit
by
means
of
the
LOW
FILTER
switch.
4,
TROUBLESHOOTING
ANALYSIS
1.
Excessive
line
consumption
a.
Check
for
shorted
O806
through
O809.
b.
Check
for
shorted
transistor
Q715,
through
Q718.
c.
Check
for
open
0709,
0710,
R717,
R718.
2.
No
line
consumption
or
zero
bias
voltage
a.
Check
line
cord,
fuse,
check
for
shorted
0709,
Q710,
0717,
O718.
b.
Check
for
open
rectifiers
Q806
through
O809
or
open
LOO1.
3.
High
hum
and
noise
level
a.
Check
filter
capacitors
C808,
C809,
C801, C803,
Q801
and
0812.
5.
POWER
AMPLIFIER
ADJUSTMENT
ADJUSTMENT
OF
IDLING
CURRENT
Connect
a
vacuum
voltmeter
to
between
emitters
Q715
and
Q717.
Adjust
R717
until
117
mV
is
reached.
Likewise,
adjust
Q716,
O718
and
R718.
6.
TEST
EQUIPMENT
REQUIRED
FOR
SERVICING
Table
1
lists
the
test
equipment
required
for
servicing
the
Model
BLA-545/A-545/BLA-530/A-530
Stereo
Console
Amplifier.
The
wattmeter,
AC
voltmeter,
and
variable
autotransformer
may
be
assembled
as
a
test
fixture
as
shown
schematically
in
Figure
1.
The
load
resistors
and
AC
ammeter
may
be
assembled
into
a
second
test
fixture
as
shown
in
Figure
2.