Table of Contents
Advertisement
|
SECTION 3
ALIGNMENT AND ADJUSTMENT PROCEDURES
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. 3-1 and listed in Table 3-1.
Check
the
color code of the filters to
identify the same center frequency when
replacing any of these filters.
TABLE 3-1.
FM LF CERAMIC FILTERS
Part No.
Color
Specified Center Freq.
1-403-562-11
red
10.70 MHz
1-403-562-21
black
10.66 MHz
1-403-562-31
white
10.74 MHz
1-403-562-41
green
10.62 MHz
1-403-562-5 1
yellow
10.78 MHz
color spot
Fig. 3-1.
Color dot on ceramic filter
| "setts
WN
Interruption of fm or a-m local
oscillator operation
Fig. 3-2.
a
{9 —
Note: Two methods of i-f discriminator align-
ment
are
available,
sweep
generator
alignment
and
signal generator
align-
ment.
You can use either of them.
In
either case, the local oscillator should be
killed.
To
stop the local
oscillator's
operation, remove the shield cover over
the local oscillator capacitor, if néces-
sary,
and
then: shunt
the oscillator
capacitor
with
a
0.02uF
capacitor.
See Fig. 3-2.
:
Sweep Generator Alignment
Test Equipment Required
1.
.10.7 MHz sweep generator
2. © Oscilloscope
3.
Ceramic capacitor, 0.02uF
4.
Alignment tools
Preparation
1.
Remove
the record
changer
as described
in
Procedure 2-4.
2.
Connect
the input
cable of the oscilloscope
with alligator clips to R221 and ground on
the fm
a-m
tuner
circuit
board,
and
solder
a 0.024F capacitor across these clips, as shown
in Fig. 3-3.
3.
Connect the output cable of the sweep gener-
Fig. 3-3.
ator across CV102 on tuner and MPX board.
Use alligator clips and make
the connection
through a 0.02zF coupling capacitor as shown
in Fig. 3-4.
é
Fm discriminator output connection
Advertisement
Table of Contents
