Sharp VC-780E

-/ouU 7
| VC-790ET ;
Linear time counter does not operate.
ay... - Problems
When system sw is in auto position,
the selection of 50/60 Hz in PB mode
does not function well.
Problems
No picture At E-E mode
appears.
At playback of
standard tape
At playback of
the tape
recorded by
oneself
Probable
causes
and
countermeasures
Chek
if
the
outputs
from
pin
52
and
pin
53
of
servo
iC701
are
sent
to
pin
9
and
pin
10
respectively.
Check
if
the
selecting
result
is
sent
from
pin
53
of
iC801
to
pin
16
of
IC802.
Chek
if
the
voltages
of
pins
17
and
18
of
IC802
are
appropriate
values
(at
PB,
pins
17
and
18
are
OV).
Check
if
the
input
signal
to
pin
16
of
IC802
is
output
from
pins
8,
9
and
10
of
[C802
(at
50Hz,
pins
8,
9
and
10
are
approx.
5V)..
Check
if
the
PB
CTL
CLOCK
signal
is
output
from
pin
47
of
1C701
and
is
input
to
pin
1
of
C802.
Check
if
pin
3
of
IC802
(RESET
terminal)
is
kept
in
resetting
(keeping
“High”
tevel).
Check
if
the
counter
pulse
is
output
from
pin
2
of
IC802
and
is
input
to
pin
20
of
[C5001
inside
of
timer
circuit.
Check if IC802 is defective.
Probable
causes
and
countermeasures
Check
if
the
video
signal
(E-E
signal)
is
applied
to
pin
4
of
1C201,
if
the
video
signal
goes
out
of
pin
10,
and
if proper
voitage
is
applied
to
each
pin
of
IC201.
Check if the video signal comes into pin 6 or pin 1
of 1C1502 and goes out of pin 8 of !C1502 (in
tuner mode). _
Check
if
the
“EE
5V”
signal
is
at
low
level
at
pin
7
of
1C1502
and
if
the
EE
(H)
signal
is
at
high
level
at
pin
12
of
1C201.
Check if the video signal comes into pin 1 of K401
and goes out of pin 5 of K401.
Make sure that there appears a normal picture at E-E
mode.
*
Check if the playback FM signal is applied to pin 4
of connector CG.
Check tf the playback FM signal is applied to pins
20 and 21 of 1C301.
Check if Vec SV is applied at pins 7 and 24 of IC401.
Check if the video signal (demodulator output) is
given at pin 9 of IC401.
Check if the video signal is given at pin 25 of |C401.
Check if the base of Q210 is at high level (approx.
4V).
Before this checking, make sure that norma! playback
is possible with standard tape.
38
check. 1f there is FM signalat pin 9 of |C401.
Check if there ts video signal at pin 6 of IC201.
Check tf there ts video signal at pin 10 of iC201.