Revox B261 Serviceanleitung Seite 46

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Fig. 4.7
Press station
sei-ector key 12 (97.925
MHz
) and adjust the
reading on the digital voltmeter to 1.8 V +10
mV
with
R95
(L.126.780, Eig.4.7).
Feed 98.0 MHz/I1
mV EMF
from the standard-signal generator
into the antenna input and adjust the reading on the
SIGNAL
STRENGTH METER
with
R76
to 90 dBf (0dBf = 0.274 yv).
FLlA
FLlB
Caution:
- Switch
- Connect
0v+10
Since
there is mutual influence, these filters
must
be
adjusted several
tj.mes
until
no
further
improvement
is
poss
ible
.
tuner off, reinstall
IC4
and
switch tuner
on again.
digital voltmeter to test point
10 and
adjust
R26
for
mV.
4.6 Adjusting the discriminator
1.726.740l780
Required test equipment:
-
FM
standard-signal generator,
unmodul"ated
- Frequency counter with
CRO
probe
10:
L
- Digital. voltmeter
Adjusting procedure:
- Switch tuner off
- Check the needle deflection of the
SIGNAL
STRENGTH
METER and
of the
CENTER TUNING
I'IETER:
The needl,e of the
SIGNAL
STRENGTH I'IETER
should be at zero,
the one of the
CENTER
TUNING METER
in the mi.ddle.
The
center tuning meter can be mechanically adjusted after
it has been
removed.
- Switch tuner on and connect frequency counter to test point
MP4
(l-.726.740, Fig. 4.5).
- Feed 98.0 MHz, approx. 2
mV EMF
from the standard-signal
generator into the antenna input and press station selector
key
3.
- Adjust frequency of standard-si-gnal generator for a reading
of
10
.'l
MHz
+ 1
kHz.
- Connect digiEal
voltmeter to test point 11 (microprocessor
PCB
1.726.180, accessible from the bottom through the cutout
in the screening plate)
and adjust with FL1 A (secondary
circuit)
to 0 V +30
mV.
- Adjust voltages 6n <ij-9itaI voltmeter
for 97.925
MHz
(station
key 12) and 98.075
tqlJ'z
(station
key 16) with FLl B (primary
circuit) to a balanced deviation
(maximum
deviation
50
mV).
R95
MP1
1
t4l9
i6t
ö