Tuner Adjustment - Aiwa TV-CN202 Service Manual

3. TUNER ADJUSTMENT

3-1. AGC Adjustment
(1) Receive a NTSC signal of RF INPUT under the following
conditions.
Input level: 58 dBµ
Modulation percentage: 87.5%
Received channel : US TV 10ch (fp = 193.25MHz)
(2) Adjust SFR201 so the voltage at the TU101 Pin1 (TP15 or
JW101) is 6.8V ± 0.2VDC.
(Simple Adjustment Method)
(1) Using the LEADER LCG-401 (65dBµ), receive the color bar
signal on channel 2.
(2) With SFR201, make adjustments so that the voltage of TU101
pin1 becomes 3.6VDC.
(3) Receive a television broadcast, and verify that the screen is
clear.
3-2. VCO Adjustment
( Rough Adjustment )
(1) Make connections as they appear below.
TU 101 Pin ! (TP2, IF)
ATT
LSW – 480
VIF
(2) Connect between Pin52 and GND of IC301 with capacitor.
+
CAP, 10/50
AC POWER
SUPPLY
TP14
10
IC301
4 4
TP12
ALIGNMENT
SCOPE
IC301
52
+
C207 0.47/50
(3) Using a DC power supply, add DC3.0V ± DC0.2V of voltage
to the IC301 Pin10 (TP14).
(4) Make adjustments with L203 so that the waveform's center
section (a section in the figure below) of the ALIGNMENT
SCOPE becomes 45.75 MHz ± 50 kHz.
45.15
(5) Remove the capacitor.
3-3. AFT Adjustment
(1) Connect the resistance of 1 kΩ between the TU101 Pin11
and the GND.
(2) Input the following signal conditions to the TU101 Pin11.
(AM/FM SSG)
CARRIER 45.75 MHz
LEVEL 100 dBµ
MOD OFF
(3) Make adjustments with L206 so that the voltage of the
IC301 Pin47 (TP16) is DC4.5V ± DC0.2V.
(4) Remove resistance (1 kΩ).
( Simple Adjustment Method )
(1) Using the pattern generator LCG-401, receive the signal for
channel 2.
(2) Adjust L206 so that the voltage at IC301 Pin47 (TP16)
becomes 4.5V ± 0.3VDC.
(3) Receive each television broadcasts and vertify that the picture
is clear.
33
46.35
a
47.75MHz
TU 101
11
TP2
1kΩ