Sharp LC-20A2U, Service Manual

Page: 12 / 42

12
LC-20A2U
TROUBLE SHOOTING TABLE
(Continued)
No picture and sound
No color
No TV
color
No S-VIDEO color
Yes
No
Do F3701 and F3702 function?
Chec
k all the settings on the microprocessor
’s adjust process men
u.
No
Are secondar
y outputs
(+38V
, +16V
, +9V
, +5V
, -8V)
of
T701 as specified?
Yes
Are the oscillation w
a
v
e
fo
rm
at T701
’s pr
imar
y side as
specified?
Yes
No
Disconnect F3701 and F3702.
Is the load side
shor
t-circuited?
Yes
No
Is an
y of
T701
’s pr
imar
y side
,
Q701, Q710 and S4701 shor
t-circuited?
Chec
k J3701, its per
ipher
al
par
ts and connection cab
le
.
Replace F3701 and F3702.
Chec
k S4701 and
connection cab
le
.
Chec
k the secondar
y-side
load of
T701.
Fluorescent lamp
Yes
No
Does F7751 function?
Yes
No
Is Pin (34) of IC1201 at
“H
”?
Yes
No
Are the oscillation w
a
v
e
fo
rms
at the pr
imar
y side of
T7751-6
as specified?
Yes
Replace F7751.
No
Is input at pin (71) of IC802 as specified? Chec
k SC3301, SC line and
per
ipher
al par
ts
.
Yes
Chec
k the line
, IC1201 and
its per
ipher
al par
ts
.
Chec
k Q7751-5,
T7751-6
and their per
ipher
al par
ts
.
Replace the fluorescent lamp and chec
k the oscillation
w
a
v
e
fo
rm
again.
No VIDEO
color
Chec
k all the settings on the microprocessor
’s adjust process men
u.
No COMPONENT color
No
Is input at pins (4) and (6) of IC802 as specified?
Chec
k J3405, CB line
, CR
line and per
ipher
al par
ts
.