Sony ST-5066 - Alignment and Adjustment; Fm I-F and Discriminator Alignment

SECTION 3
ALIGNMENT
AND
ADJUSTMENT
3.1,
FM I-F
AND DISCRIMINATOR
ALIGNMENT
CAUTION
The
ceramic filters
in
the
fm i-f
circuit
are
selected
according
to
their specified
center
frequencies
and
color coded
as
shown
in
Fig.
3- l and
listed
in
Table 3-
l
.
Check
the
color
code
of the
filters
to identify
the same
center
frequency when
replacing
any
of these
filters.
TABLE
3.1.
FM
I.F
CERAN{IC
FILTERS
Signal Generator
Method
Test Equipment
Required
1. Signal
generator
capable
of
generating
a
10.7
MHz
a-m/fm signal.
2. Oscilloscope
Vertical
sensitivity
3.
Ac VTVM
4. Aligpment
tools
Preparation:
100
mV/cm
minimum
l.
Connect the input
cable
of the oscilloscope
with
alligator
clips
to R
227
and
ground
on the
fm
(a-m)
front-end/i=f
amp/MPX
board, and solder
a 0.02pF
capacitor
across
these clips
as shown
in
Fig.
3-3.
2.
Connect the
output cable
of the
generator
across
CVl02
on
the
fm
(a-m)
front-end/i-f amplMPX
board through a 0.02pF
coupling
capacitor
as
shown
in Fig.
3-4.
Fig.
3-3.
Fm discriminator
output
connection
Part
No. Color
l-527-220-11
red
l-527-220-21 blue
l-527-22G31 orange
l-527-220-41
black
l-527-22G'51 white
Specified
Center
Freq.
10.70
MHz
10.67
MHz
10.73
MHi
10.64
MHz
lO.7 6
MHz
color*rï
Fig.3-1. Color
dot
on
ceramic
filter
crt03
fm
os
trimmer
Fig. 3-2. lnterruption
of
fm
or a-m local
oscillator
operation
Note:
Local oscillator should
be
killed when
performing
this alignment.
To stop
the
local oscillator operation,
shunt
the
oscil-
lator
capacitor
with a 0.02pF
capacitor
as shown in
Fig.
3-2.
6
F ig,
3-4.
I
0.7MHz
signal
iniection