Sharp 20U200 - PIF ADJUSTMENT; Tuner IFT (PRESET) Adjustment; RF-AGC TAKE OVER POINT ADJUSTMENT

7
20U200, 20U250
51U200, 51U250
51U500, 51U550
7-1 7-2
SHIPPING SETTING & CHECKING
(1)The following default data has been factory-set for the E
2
PROM.
(By press factory setting 3 key)
ITEMS DATA SETTING
LAST PROGRAM/CHANNEL 1
FLASHBACK PROGARM/CH 1
DIGIT 2
C-SYSTEM AUTO
S-SYSTEM B/G
SKIP OFF
AFC ON
VOLUME 1
CONTRAST 60 (MAX)
COLOUR 0 (CENTER)
BRIGHTNESS 0 (CENTER)
TINT 0 (CENTER)
SHARPNESS 0 (CENTER)
WHITE TEMP STANDARD
REMINDER TIMER In-active, "--:--"
ON TIMER In-active, "--:--"
OFF TIMER In-active, "--:--"
LAST POWER POWER-ON
LANGUAGE ENGLISH
BLUE BACK MUTE ON
HOTEL MODE OFF
0 CHANNEL SKIP ON
LAST TV/AV TV
BASS/TRE/BAL CENT
SURROUND OFF
SURROUND LEVEL CENT
PIF ADJUSTMENT
NO. Adjustment part Adjusting procedure and conditions Waveform and others
1
Fig. 1
2 RF-AGC
TAKE OVER
POINT
ADJUSTMENT
(I
2
C BUS
CONTROL)
1. Receive "PAL COLOUR BAR" signal.
» Signal Strength: 57 ±1 dBµV (75 ohm open)
2. Connect the oscilloscope to TP201 (Tuner’s
AGC Terminal) as shown in Fig. 3.
3. Call "AG" mode in service mode. Adjust the
"AG" bus data to obtain the Tuner output pin
drop 0.1 V 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.
Note:
For the 50 ohm signal strength
gauge, when not using 50/75
impedance adapter, signal
strength is 52 ±1 dBµV(75 ohm
open), instead of 57 ±1 dBµV
(75 ohm open).
For the 50 ohm signal strength
gauge,
Precaution:
The loss of using impedance
adapter.
» Bias box: About 4.5 V
Oscilloscope
0.1V
TV Set
Bias box
TP201+
+
–
–
Tuner IFT
(PRESET)
1. Get the tuner ready to receive the E-9 CH
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
position during this adjustment.
E-9 CH
P C
10k
100k
1n60
75ohm
IF OUT
-1.5+/-0.8dB
1000p
Oscilloscope
Fig. 2
Fig. 3
Note: After pressing MODEL setting. 0 channel will be skipped.