Sony ST-88 - FM Alignment: IF and Discriminator; IF and Discriminator Alignment Procedure; FM Alignment Test Equipment and Preparation; FM Alignment Signal Generator Method

SECTION 3
ALIGNMENT AND ADJUSTMENT
3-1. FM I-F AND DISCRIMINATOR Simel oorerster menos «
ALIGNMENT : ;
S Test Equipment Required
CAUTION
1, Signal generator capable of generating a 10.7 MHz
The ceramic filters in the fm i-f circuit are a-m/fm signal.
selected according to their specified center fre-
quencies and color coded as shown in Fig. 3-1 2. Oscilloscope
and listed in Table 3-1. Check the color code of Vertical sensitivity 100 mV/cm minimum
the filters to identify the same center frequency nae
when replacing any of these filters. 3. Ac VIVM
4. Alignment tools
TABLE 3-1.
FM I-F CERAMIC FILTERS Preparation:
Part No. Color Specified Center Freq. 1. Connect the input cable of the oscilloscope with
Higator cli -
ees sana ie 10.70 MHz alligator clips to R229 and ground on the fm (a-m)
front-end/i-f amp/MPX and preamplifier board, and
ESgeaeee! pits sp tetales solder a 0.02 uF capacitor across these clips as '/.
1-527-220-3 1 orange 10.73 MHz aye Fi P P ;
1-527-220-41
black
10.64
MHz
ai
Re:
1-527-220-51 white 10.76 MHz 2. Connect the output cable of the generator across
CV102 on the fm (a-m) front-end/i-f amp/MPX
and preamplifier board through a 0.02 uF coupling
. capacitor as shown in Fi
color dot a BPR 5 AMES AER
Fig.
3-1.
Color
dot
on
ceramic
filter
y
;
€
iz) 02 uF
S% ‘er fzas R2 Rel
a-M osc
trimmer
Fig. 3-2. Interruption 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 0.02 UF capacitor
as shown in Fig. 3-2. To rf signal {
generator
Fig. 3-4. 10.7-MHz signal injection