Sharp 21N52-E1, Руководство по обслуживанию

Страница: 4 / 44

ADJUSTMENT
(Continued)
AFT COIL ADJUSTMENT:
Connect sweep generator’s output to pin
of IF unit.
l
Probe in use: DC cut probe
l
Sweep output level:
Adjust to align the marker with the
base line.
Connection Diagram of DC Cut Probe.
Apply DC to (pin of
Connect response lead to pin of IF unit.
(The response lead should be a direct probe
with a 1 Ok ohm resistor included.)
l
Tune off AFT Mute.
Align the IF marker with the
base line.
To I
To pin
l
Adjust the sweep generator’s sweep range
to obtain normal S-curve on the oscilloscope
screen.
l
Adjust the IF voltage so that the
curve’s amplitude be
AFT COIL:
Before this adjustment, the AFT coil
(rough adjustment) must have been
completed.
Receive “PAL COLOUR BAR” signal with
bar generator.
Signal strength: Over Below
Connect oscilloscope to
l
Oscilloscope range:
l
Sweep time:
l
Synchronization: Horizontal sync.
Connect the output of (Standard Signal
Generator) to the tuner IF output terminal
across a capacitor of 1
l
output frequency:
MHz
MHz 5
l
output level:
Adjustment error: MHz
* When the preset switch is set at U or
V
position,
AFT
is turned off.
.
Set the preset switch at V position and adjust
FINE button (Up or Down) of tuning control so
that the output waveform suffers no beating.
Set the preset switch at NORMAL position.
Adjust so that no beating is caused at
the output waveform.
Finely adjust to make zero the beating