Specifications

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SYMPTOM
Grey-white screen WITH
fllsh ocCllrrin,
on
tM
TV
,
scre.n
when
relit
switch
is
depreald.
(continued)
Incorrect,
extr.,
or
missing
video
patterns
or
characters.
Distorted
TV
picture.
No
sound
(picture
and
vidlo OK),
SUSPECT
Defective
IC
(continued
I.
Incorrect
or
missing
bus
control
signals,
Solder bridges
or
foreign material
causing
shons.
One
or
more
les
are
defective.
Incorrect
or
missing DC Voltages.
Test
Clrtridge
is
defective.
Solder bridges
or
foreign material
is
causing
shorts.
Interference from a nearby television
or
radio transmitter.
•
The
tlSt
setup
is
incorrect.
STIC
IC
(U4) or Color
IC
(Ul01
is
defective,
Defective
RF
modulator.
Solder bridges
or
foreign material
causing
shorts.
TV
volume
tumed
down,
-15-
REMEDY
If
Test Routine
will
not
run (using
I
known-good
test
canridge)
Ind
III
voltages are OK, repllce
tM
ICs
in
the
following
order:
Ul,
U2, U4, U3,
or U6.
Review
procedure
in
Troubleshooting
Guide
on
checking bus control signlls.
Remove
any
foreign mattrial
or
solder
shons.
Insen
test
canridge
Ind
Dilgnostic Test
Routine. Replece
Iny
indicated
ICs.
Most graphics problems
Ire
c..,sed
by U2, U4, U5, U7,
or
US.
Check for
correct
DC
voltlges
on
8Ich
IC
(refer
to
SchematiC, Figure SI.
Try a known-good Test
C.nridge.
Remove
any
foreign material
or
solder
shons.
Switch television and Master Component
to another channel
andlor
disconnect
the
antenna wire from
the
antenna
switch box.
Check
all
television controls
and
can·
nections for
agreement
between
the
TV
VHF channel selector and
the
Master
Component
channel selector.
Replace these
ICs
(one
at
a timel with
known-good
ones.
Connect
a
known·good
modulator in
parallel
with
the
modulator.
Connect
the
RF coble
to
the
known-good
modulator
and
touch
the
two
modu·
lator cases
together.
If
the
problem
clea<1,
replace
the
modulator.
Remove
any
foreign material
or
solder
bridges.
Check TV Volume setting.
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