Sharp 21C-FX1G 서비스 매뉴얼 - 페이지 8
{카테고리_이름} Sharp 21C-FX1G에 대한 서비스 매뉴얼을 온라인으로 검색하거나 PDF를 다운로드하세요. Sharp 21C-FX1G 44 페이지.
페이지 인쇄
PIF ADJUSTMENT
No. Adjusting point
Adjusting procedure/conditions
1
Tuner IFT
1. Get the tuner ready to receive the CH. E - 9
( PRESET )
signal,but with no signal input.
Adjust the PLL data.
2. Connect the sweep generator's output cable to
the tuner antenna. ( RF SWEEP )
3. Adjust the sweep generator's to 80dBµV.
4. Connect the response lead ( use LOW IMPED-
ANCE probe with wave detector ; see Fig.1 ) to
the tuner's
IF output terminal. ( This terminal
must have the probe alone connected ).
5. Set the RF AGC to 0 - 6 V with no saturation with
the waveform.
6. Adjust the tuner IF coil to obtain the waveform as
shown in Fig. 2.
Note: Be sure to keep the tuner cover in posi-
tion during this adjustment.
2
RF-AGC
1. Receive "PAL COLOUR BAR" signal.
» Signal Strength: 54 ± 1 dBµV (75 ohm open)
TAKE OVER
POINT AD-
JUSTMENT
2. Connect the oscilloscope to TP201 (Tuner's AGC
(I2C BUS
Terminal) as shown in Fig. 3.
CONTROL)
Oscilloscope
+
0.1V
—
Bias box
+
—
» Bias box: About 4.5 V
Fig. 3
3. Call "AGC" mode in service mode. Adjust the
"AGC" bus data to obtain the Tuner output pin
drop 0.1V below maximum voltage.
4. Change the antenna input signal to 63~67dBµV,
and make sure there is no noise.
5. Turn up the input signal to 90~95 dBµV to be sure
that there is no cross modulation beat.
Waveform and others
10k
1n60
1000p
Oscilloscope
100k
1000p
75ohm
Fig.1
E-9 CH
P
-1.5+/-0.8dB
Fig.2
Note: For the 50 ohm signal
strength gauge, when not
using
50/75
impedance
adapter, signal strength is
±
µ
52
1dB
V(75 ohm open), in-
±
µ
stead of 54
1dB
V (75 ohm
open).
TP201
Precaution: The loss of using
impedance adapter.
TV Set
8-1
SIF (NICAM/IGR) ADJUSTMENT
No. Adjusting point
Adjusting procedure/conditions
1
VCO COIL
1. Receive "PAL colour bar" signal.(E-69)
T2300
(Set AFT ON 855.25MHz frequency).
2. Connect DC Voltmater to TP202 (MAIN BOARD
TEST POINT).
3. Check and turn T2300 counter-clockwise (Left)
to 0V and then turn it clockwise (Right) until TP202
IF OUT
become 5V.
After that, turn T2300 counter-clockwise (Left) until
TP202 became 2.5 ± 0.1Vdc.
* UNIT BOARD ADJUSTMENT
Vcc
IF Input Frequency 38.9MHz ± 0.1V
C
Adjust T2300 unit TP2300 (NICAM BOARD TEST
POINT) become 2.5 ± 1.0V
Check after assembly NICAM BOARD
Test point: TP202 (IN MAIN BORD).
Preset selected receptiion frequency (AFT OFF)
Check Voltage 2.5 ± 1.0Vdc.
Precaution: The Vcc, fo and other factors are
Waveform and others
*For model
21C-FX5 and 21C-FX8
5V ± 0.1V
considered in theunit board of
the 1.0V tolerance which differ
from the adjustment accuracy.
8-2