14Gt15 - Sharp 14GT15 Service Manual

No. Adjusting point
1 Tuner IFT 1. Get the tuner ready to receive the CH. E - 9
( PRESET )
2. Connect the sweep generator's output cable to
3. Adjust the sweep generator's to 80dBuV.
4. Connect the response lead ( use LOW IMPED-
5. Set the RF AGC to 0 - 6 V with no saturation with
6. Adjust the tuner IF coil to obtain the waveform as
Note: Be sure to keep the tuner cover in position
2 RF-AGC 1. Receive "PAL COLOUR BAR" signal.
TAKE OVER
POINT AD-
JUSTMENT 2. Connect the oscilloscope to TP201 (Tuner's AGC
2
(I C BUS
CONTROL)
3. Call "AGC" mode in service mode. Adjust the
4. Change the antenna input signal to 63~67dB V,
5. Turn up the input signal to 90~95 dB V to be sure
PIF ADJUSTMENT
Adjusting procedure/conditions
signal,but with no signal input.
Adjust the PLL data.
the tuner antenna. ( RF SWEEP )
ANCE probe with wave detector ; see Fig.1 ) to
the tuner's IF output terminal. ( This terminal
must have the probe alone connected ).
the waveform.
shown in Fig. 2.
during this adjustment.
» Signal Strength: 57
1 dB V (75 ohm open)
Terminal) as shown in Fig. 3.
Oscilloscope
+
0.1V
–
Bias box
+
–
» Bias box: About 4.5 V
Fig. 3
"AGC" bus data to obtain the Tuner output pin
drop 0.1V below maximum voltage.
and make sure there is no noise.
that there is no cross modulation beat.
Oscilloscope
Note: For the 50 ohm signal
TP201
Precaution: The loss of using
TV Set
11
Waveform and others
1n60 1000p
10k
100k
75ohm
Fig.1
E-9 CH
P C
-1.5+/-0.8dB
Fig.2
strength gauge, when not
using 50/75 impedance
adapter, signal strength is
52 1dB V(75 ohm open), in-
stead of 57 1dB V (75 ohm
open).
impedance adapter

14GT15

14GT20
IF OUT