Sharp VC-90ET

VC-9OET
ADJUSTMENT
OF
IF
CIRCUIT
4.
Using
the
signal
generator,
feed
the
38.9-
Adjustment
of
RF
AGC
MHz
+
1kHz
PIF
frequency
signal
{sine
wave)
to
the
tuner IF output terminal.
Measuring Oscilloscope
instrument Signal generator
(Adjust the attenuator to attenuate the input
signal down to an appropriate level).
5. Adjust T002 (AFT coil) in the IF pack so that the
Input signa! Colour bar signal
Video output terminal
Adjusting point VROO1 (on IF pack)
video output terminal waveform be minimum.
1. Receive the colour bar signal (input field strength:
80 dBy).
2. Observe the video output terminal waveform on
the oscilloscope. Adjust VR001 (on IF pack) in the
IF pack until the noise disappers from the
oscilloscope screen and the waveform nearly
comes into sync.
“>
Just before shrinking
Figure 2-25.
Adjustment of AFT
Measuring Oscilloscope .
instrument Signal generator
Input signal
PIF frequency uniwave
(38.9 MHz + 1kHz)
Colour bar signal (70 dBy)
Test point Video output terminal
Adjusting point {| T002 (AFT coil)
Specification
1. Receive the colour bar signal (input field strength:
70 dBy).
2. First set the band selector switch to VHF or UHF
Position.
Using the signal generator, feed the 38.9-MHz PIF |
frequency signal (sine wave) to the tuner IF output |
terminal. |
Use the (-) and (+) keys so that the video output
terminal waveform be minimum. |
3. Set the band selector switch normal position. :