Daewoo 2898ST, Service Manual

Page: 12 / 72

12
SIF ADJUSTMENT
1. APPARATUS CONNECTION & PRESETTING
* CONNECTION
1) Connect H-out of LSW-480 to X-axis of the
oscilloscope and V-out of LSW-480 to Y-axis
of the oscilloscope.
2) Connect the sweep signal output to TP1.
3) Set ATTENUATOR of LSW-480 to 20dB.
4) Supply 12V D.C. voltage(B+) to TP3.
5) Supply 3V D.C. voltage(B+) to TP4.
6) Connect the test point of LSW-480 to TP2.
7) Adjust L109(AFT COIL) so that the P marker
point is located on the reference level.
* PRESET
1) Oscilloscope Scaling
a) Put the scale of X and Y of the oscilloscope
to D.C. level
b) Set the horizontal time display to X-Y.
c) Put the horizontal axis (x) to 1V / div. and the
vertical axis (Y) to 2V / div.
2) LSW-480 MARKER FREQ. SETTING
fp(n+1)
31.9
fs
33.4
fc
34.47
fp-2
36.9
fp
38.9
fs(n-1)
40.4
PIF SWEEP MAKER (LSW-480)
GENERATOR
OUTPUT
H-OUTPUT
V-OUTPUT
FROM TP
TP1 (TUNER IF)
TP3 (TUNER B+)
TP2 (I603 #12)
TP3 (I603 #3)
DC POWER SUPPLY
(+12V)
DC POWER SUPPLY
(+3V)
OSCILLOSCOPE
X
Y
- Connection For SIF Adjustment -
Y
X
P
(38.9 MHZ)