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Tektronix 7704A Manual

Tektronix 7704A
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1460
/
BURST
GAIN
"
BOUNCE
"
WITH
SOUND
IN
SYNC
Reference
:
1460
Manual
P
/
N
070-1803-00
Schematic
:
10
T1B
12a
1460
instruments
used
in
Sound
-
in
-
Sync
applications
may
exhibit
Burst
and
/
or
Chroma
gain
"
bounce
"
.
The
sync
sampling
pulse
for
decoders
(
U4651
A
&
B
)
has
sound
-
in
-
sync
(
S
-
1-5
)
present
.
This
causes
faulty
clamping
at
TP4351
and
TP4721
.
The
end
result
is
varying
burst
and
chroma
gain
on
the
output
.
To
correct
this
malfunction
,
lift
the
end
of
C4346
(
A4
decoder
circuit
board
)
connected
to
the
collector
of
Q4253
.
Reconnect
this
lead
to
the
base
of
Q4244
.
Since
the
signal
present
on
the
base
of
04244
comes
from
the
S
-
I
-
S
reject
circuitry
(
U4136
A
&
B
)
,
it
does
not
have
S
-
I
-
s
present
.
The
chroma
gate
pulse
at
P4699-1
(
Schematic
12a
)
is
too
wide
and
allows
the
sync
pulse
at
the
end
of
the
VIT's
line
to
pass
.
The
S
-
I
-
S
on
this
sync
pulse
is
decoded
by
U44568
and
14466
and
is
passed
as
a
DC
level
shift
by
the
sync
-
sampling
pulse
.
To
correct
this
problem
,
the
chroma
gate
pulse
is
shortened
by
adding
an
R
-
C
network
to
U3352
.
On
the
back
side
of
board
cut
the
run
going
to
pin
1
of
13352
(
see
drawing
)
.
Solder
one
end
of
2.7K
ohm
resistor
(
315-0272-00
)
to
the
end
of
R3332
connected
to
U3342
pin
4
(
+
5v
)
.
Solder
one
end
of
another
2.7
K
ohm
resistor
(
315-0272-00
)
to
ground
(
see
parts
locator
diagram
included
)
.
Solder
one
end
of
a
470pf
capacitor
(
283-0197-00
)
pin
3
of
13352.
Solder
the
other
end
of
the
capacitor
and
both
free
ends
of
the
two
resistors
to
pin
1
of
43352.
This
modification
should
be
installed
as
units
come
in
for
service
.
C
Thanks
to
Bill
Gobel
,
EMC
,
and
Eric
Rogstad
,
TV
Engineering
,
for
providing
this
information
.
(
continued
on
the
following
pages
)
--Steve
Schmelzer
58-511
,
Ext
.
6507
-16
June
27
,
1980
Issue
10-13

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Tektronix 7704A Specifications

General IconGeneral
BrandTektronix
Model7704A
CategoryTest Equipment
LanguageEnglish

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