Filter
Top Products
r
<**
r
50
ohms
resistance
with
negative
ohmmeter
polarity
on
the
center
conductor.
(With
positive
polarity
on
center
conductor,
resistance
should
be
between
20
and
30k
ohms.)
See
"Coaxial
Cable
Replacement".
Selector
Switch
UnitTests
The
quickest
test
for a
troublesome
Selector
Switch
Unit
is
substitution
witha
new
unit
(see
Parts
List).
If
a
new
unit
is
unavailable,
usea
DC
voltmeter
and
ohmmeterto
check
unit
circuitry
(see
schematic
of
Fig. 19)
for
open
or
short-circuited
components.
TWINLEAD
TV SET
CONNECTION
GAMEINPUT
TERMINALS
A A
>-9-
(PHONO
J1
JACK)
N
H
TRANSFER
SWITCH
1
O
1-
I 0=
1
o r
J3
TV
ANTENNA
TERMINALS
STUDIO
I
RFC2
A
A
DCINPUT
TERMINALS
(PHONE JACK)
Figure
19.
Schematic,
Selector
Switch
Unit
When
the
switch
is
in the
"Studio
II"
position,
it
connects
the
coaxial
cable
from
the
consoleto
the
twin
lead and
com-
pletes
the DC
circuit
between
the
console
and
power
supply.
With
the
switch
in
the
"TV"
position,
it
disconnects
thecon-
sole
and
formsa
circuit
between
the
antenna
terminals
and
the
twin
lead
for
normal
TV
reception.
If the
Selector
Switch
Unit is
defective,
itmust
be replaced
(see
Parts List)
since
it
cannot
be
satisfactorily
repaired in
the
field.
It is
carefully
manufactured
so
as
not
to
exceed
the
RF
radiation
limits
specified by
the
FCC.
Ifsnowy
pictures
occur
in the
"TV"
position
or
Studio
II
cannotbe
shutoff,
check
antenna
connections
for
short
circuits
to
the
metal box
or
rivets
holding
terminal
board.
If either
antenna
lead
touches
the box
or
rivets,
snowy
pictures
may
result.
(Late
production
units use
insulated
rivets
which
eliminate
problem))
Power Supply
Unit
Tests
The
Power
Supply
Unit
operates
between
carefully
chosen
voltage
and
ripple
limits.
To
check unit
for
satisfactory
opera-
tion,
connect
unitas
shown
in Fig.
20. DC
output
under
these
conditions
ranges
between
8.5
and
10V.
Rippleon
this
DC
(measured
with
oscilloscope)
must
not
exceed
1
V
peak-to-
peak.
Replace
unit if
beyond
these
specifications
(see
Parts
List).
Leakage
Current
Test
Withthe
Power
Supply
Unit
plugged
into
an AC
outlet,
check
for
leakage
currentto
earth
ground
on
both poles
of
the
phoneplug,
as
shown
in
Fig.
21,
using
an AC
milliam-
meter.
Leakage
current
mustnot
exceed
0.5mA.
Reverse
AC
plug
polarity
and
recheck
leakage
current.
EARTH
GROUND
Figure
21. AC
Leakage
Test
NOTE:
If
powerunit
checksout
OK
but
is inoper-
ative
with
operable
Studio
II console,
checkfit
of
plug-in jack.
Some
early
production
plugs
andjacks
havetolerances
that
conflict
and
prevent
adequate
plug
penetration.
Solutionto
problem is
often
simply
to
increase
effective
length of
plugby
filing the
jack
slightly as
shown
in Fig.
22. (Use
sharp
knifeto
remove
any
untrimmed
mold
flash
from
plug
if
present.)
r
\
-ft-
TO
120V
AC
LINE
ADJUST
FOR
250 mA
ON
MILLIAMMETER
FILE OR
SHAVE
SLIGHTLY
TO INCREASE
PLUG
PENETRATION
—^
Figure
20.
Testing
Power
Unit
Output
for
Voltage
and
Ripple
Content
Figure
22.
Removal
ofMaterial
from
FrontEdge
of
Jack