Specifications
for
240
Volt
Operation
1 ( ) Connect
the
violet-and-white
lead
to lug # 1 of ter-
minal
strip
TS-l.
) Connect
the
black-and-white
lead
to lug
#1
of ter-
minal
strip
TS-1
(S-2).
3 ( ) Connect
the
black
lead
to
lug # 1 of
AC
outlet
B
(S-2).
4 ( ) Connect
the
violet lead to lug A on
the
fuse
. holder
(8).
When using
the
240 volt connection, a one
ampere
slo-
blo fuse should be
used
instead
of
the
two
ampere
fuse
recommended for
the
120 volt connection.
IN
CASE
OF TROUBLE
Although
your
SCA-35 should function
properly
after
assembly, sometimes
an
error
of wiring
or
a defective com-
ponent
may
require trouble shooting.
The
location of a
difficulty
can
be determined most efficiently if a syste-
matic
approach
is
used.
This
is based
on
understanding
the
inter-relationship between
the
different sections of
the
circuit,
and
reference to
the
section which describes
the
circuit will be helpful in achieving
this
understanding.
The
suggestions for servicing which follow
are
based on
trying
to localize the circuit section which is
at
fault.
Naturally,
you
should
check
and
double check
your
wir-
ing
as
a first
step
in trouble shooting.
It
is good
to
have
somebody else check
it
through for you,
as
he
may
see
an
error
which
you
overlook consistently.
This
checking
can
be done with
the
pictorial diagrams
or
with
the
step-by-
step instructions.
If
you
use both,
you
will have a double
check
on
the
accuracy
of wiring. Look
not
only
to see if
all
ires
and
components
go
to
the
correct points,
but
also to
see
that
all
solder connections
are
good
and
that
no
wires
or
parts
touch spots where
they
should not. Sometimes a
bit
of solder will
run
from one
point
to
another
where no
connection is desired. Sometimes a lead is left
too long
and
hangs out, touching
another
point. All connections
should be examined
with
this
in mind.
Another
source of trouble is
that
wires
are
twisted so
tightly together
that
they
break
through
the
insulation
and
cause
short
circuits -
or
the
wire itself
may
be broken
within the insulation if twisted too tightly.
One general test should be
made
before serious trouble
shooting begins.
This
is to determine whether
the
fault
is
in
the
SCA-35
or
in
associated equipment. Sometimes, con-
nections to
the
loudspeakers
are
at
fault,
or
it
may
be
that
the
pickup cartridge is
not
connected properly in
the
player.
Pilot
Light
and/or
Tubes
Do
Not
light
If
after
plugging
the
SCA-35
into
an
AC
outlet
and
turning
the
power switch on,
the
pilot light does
not
go
on,
see whether
there
is a
normal
glow
in
the
center
of
the
tubes.
If
the
tubes glow while
the
pilot
light does
not
light,
then
the
fault
is in
the
pilot
light itself -
and
the
bulb
should be replaced -
or
in
the
wiring to
the
pilot
light
socket.
This
wiring should be traced to see whether
the
connections
are
correct
and
soldering makes good contact.
If
some of
the
tubes light,
but
others
do not,
then
the
heater
wiring to
the
unlighted
tubes
should be traced.
There
are
two sets of
heater
wires, a
set
for
each
channel, one of
~hich
is brown
and
brown-white,
the
other
green
and
green-
\
....
hite.
These
should be traced from
the
PA-774 transformer
to TS-2 to see
if
the
wiring compares with
the
pictorial
diagram.
If
all
the
tubes
in
one
channel
light,
but
none
in
the
other
channel,
interchange
the
brown with green wires
and
brown-white with green-white
temporarily
to
determine
whether one of these sets
of
windings is defective.
For
example,
if
the
interchange
should
make
tubes
light which
were formerly
not
lighted,
then
there
is
nothing
wrong
with
the
wiring to the tubes,
hut
most probably there is
something wrong with
the
wiring from
the
transformer
(which should be
returned
to
DYNA
Company
for replace-
ment
in
this
case).
This
principle of
substitution
is helpful
for locating
the
source of trouble.
If
neither
tubes
nor
pilot lamp light,
then
the
first
thing
to check is
the
fuse.
If
this is blown,
another
of
the
same
rating
should be used, 2
ampere
(except
1
ampere
for 240
volt
models).
If
the
second fuse blows,
then
it
is essential
to
determine
the
reason for this
instead
of continuing to
replace fuses.
Under
no circumstances should. a fuse
of
higher rating be used.
Siown
fuses
The
fuse will blow
if
there
is a
short
circuit in
the
equip-
ment.
If
an
ohmmeter
is available, resistance measurements
should be
made
at
the two
and
four-section electrolytic
capacitor
terminals.
Unplug
the
power cord
and
discharge
each section of
the
capacitor
to ground before making
any
of
these
measurements.
The
resistance to ground should be
over 50,000 ohms
on
all sections except
the
blank
terminal
of
the
four-section
capacitor
where
it
should be
about
95
ohms. Any lesser resistance values indicate
either
capacitor
failure
or
a
path
to chassis which
should
not
exist. Discon-
nect
wires to each
capacitor
section to isolate
the
capacitor.
All sections should
read
high resistance once wires
are
disconnected - if not,
the
capacitor
is
at
fault.
If
one of
the
silicon diodes is defective,
or
if
it
has been
installed
backwards,
the
four-section
capacitor
will prob-
ably
have been
permanently
damaged.
In
similar
fashion,
if
the
four-section
capacitor
is defective,
it
may
cause the
failure of
the
silicon diodes. Therefore, if
either
capacitor
or
diodes
are
found to be
at
fault, both should be replaced.
Blown fuses
can
also indicate a defective PA-774 trans-
former
(though
this
is
a
rare
possibility).
To
check for
this, disconnect all leads of the PA-774 except the two
black
primary
leads;
and
with these leads
in
position where
they touch
neither
each
other
nor
other
components, plug
in
the
unit
and
turn
it
on.
If
the
fuse blows
under
this con-
dition, the trouble is definitely in
the
PA-774.
If
the·PA-774
is proven satisfactory
in
this test,
test
the
diodes
and
capacitors
by
disconnecting all wires to
the
capacitors
except
the
wire from lug
#2
on
TS-l
to lug
#3
of
the
four-section filter capacitort leaving
the
resistors on
the
capacitor
terminals.
If
plugging in
the
unit
and
turning
it
on
then
does
not
blow a fuse, these components
are
exoner-
ated,
and
it
is necessary to seek a
short
circuit elsewhere
in
the
circuit.
The
output
tubes
can
be tested
as
the
source of blown
fuses by removing
all
the
6BQ5's
simultaneously
from
their
sockets.
If
this cures fuse blowing,
then
one of
them
is
probably bad.
The
unit
should
never be
operated
with
only
one, two
or
three
of
these
four tubes
inserted
or
damage to
the
remaining tubes is probable.
Heater
glow
at
the
top
and
bottom of each tube is normal,
but
if
the
plate
(the
large
black metal
part)
of
the
output
tubes glows red
it
indicates
a probable
short
in
the
tube
or
at
pin
#3
of
any
of
the
out-
put
tube
sockets,
or
a
short
to
the
chassis of some
part
of
the
heater
wiring.
17