Revox A76 Service Manual

VTVM
Fig.
4.7.-1
Fig.
4.7.-2
the send
level
of the
test
generator
which
must
cause a
corresponding
rise
of
the
signal as
indicated
on
the
VTVM.
4.6.8.
Note
the value
of
the
output
level as
read
on
the test ge-
nerator
4
6.9.
Alter
the frequency
of
the
test
generator
by
±
300
kHz
while
increasing the
output
level
from the
test
generator
by
60
dB
During
this test, the
signal
as
indicated
on the
VTVM
must
remain below 1 V
(static
selection 60
dB)
4.7.
Alignment of
RF input
section
Test
equipment:
Test
generator,
frequency
90
MHz, 0.2
mV
o.c.v. no
mo-
dulation
VTVM
with RF
probe,
range
to
read 0.9
V
4.7.1.
Tuner:
power
switch
depressed
4
. 7.
2
.
Checking
of dial and
pointer.
Run
pointer
from one
extreme
end
of
dial to the
other and
check
whether
or not
pointer
travels
the
full
length
of
the
dial.
4
. 7. 3.
Connect
RF
probe
of VTVM
to
test
point
5
(see
fig.
4.7.-1
)
4.
7. 4.
Connect test
generator
to the
tuner's 60
ohm
input (
BNC/59
)
4
.
7
.
5
.
Turn
pointer
exactly to 90
MHz
mark
on the
dial.
4
. 7.
6
.
Adjust
oscillator slug
LI 07
until
a
zero
indication
is obtained
on the
centre
tuning
meter
(
44).
This
adjustment
is
carried
out
from the
soldered
side
of
the
print
(
see
fig.
4.7.-2
)
4
. 7. 7
.
Adjust coils
LI
03/Ll
04
and L105
of
the
tuned
RF
stages
to
obtain
a
maximum
reading
(
adjustment
from
soldered side,
see
fig.
4.7.-2)
VTVM
reading
for tuned
RF input
section:
0.9
V (
+0.5/
-0.2
V)
4.7.8.
Set
test
generator
to the
frequency
of
106
MHz.
Move
pointer
exactly
to the
106
MHz mark
on the
dial.
4.7.9.
Adjust
oscillator
trimmer Cl
19 to
obtain zero
indication
on
the
centre
tuning
meter
(44).
(This
adjustment
is
carried out
from the
soldered
side, see
fig.
4.7.-2)
4.7.10.
Adjust
trimmer
capacitors Cl
03,
Cl 09
and Cl 10
in
the
tuned
RF
input stages
to obtain a
maximum
reading.
(Solde-
red
side, see
fig.
4.7.-2)
VTVM
reading
for tuned RF
input
section: 0.9
V (
+0.5/
-0.2
V)
4.7.11.
Repeat
alignment
procedures
4.7.5.
to 4.7.7.
and 4.7.8.
to
4.7.10.
until no
further
Improvement can be
observed.
4.7.12
Adjust
coil
LI
06
to
obtain maximum
reading
(at 90
MHz
or
106
MHz).
(
This
adjustment
is to be
carried
out
from the
component
side
of
the
print, see
fig.
4.7.-3)
4.7.13.
Adjustment
of oscillator
transformer
LI
08:
Connect RF
probe
of VTVM
to
test
point
12,
meter
range
to read
1 V (see
fig.
4.7.3.
)
Set
pointer
to the 100
MHz
mark on the
dial.
Adjust
oscillator
transformer LI
08
to
obtain
maximum
reading.
VTVM
reading: 0.7
V
(±
0.1 V)
Check to
make
sure that an
identical
signal
drop
of
2
dB
occurs
on both
ends
of
the
dial.
12

Revox A76 Specifications

General

Brand	Revox
Model	A76
Category	Tuner
Language	English