Sharp 8C221, Руководство по обслуживанию

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RF AFT ALIGNMENT
Test Equipment Connections*
Refer to Figure 9 .
GENERAL . . . . . . . . . . . . . . . . Set channel selector to the highest
unused channel.
Read the General Alignment
Instruction (Page
Connect.
AC
power plug through the isolation
former to power supply.
. . . . . . . . Connect through a direct probe to
Calibrate for a two inch equal P-P
display.
Note: Set base line in of CRT for reference.
SWEEP GENERATOR . . . . . . . Connect the IF video output
through the Output Pad
A
or (Figure ) Set
for a 1
V
P-P output.
MARKER GENERATOR . . . Adjust to produce
MHz couple loosely to Sweep Generator output cable
to provide marker.
ALIGNMENT PROCEDURE
Before attempting this alignment, check the response and realign if necessary. Make sure that the signal appearing at the
output of the video detector has an amplitude of P-P.
STEP ADJUSTMENT
SWEEP M A R K E R
GENERATOR GENERATOR
COMPONENT PROCEDURE
1
Readjust Marker Generator for visible marker, if necessary, without distorting the response
2 Move the core of to its bottom end of range.
3 Transformer
Adjust to obtain the maximum amplitude
I
and response “A” as shown in
4 AFT Discriminator
Adjust to bring marker to the
of S curve as shown in Figure
APT Transformer
Adjust to make the S curve symmetrical
as shown in Figure
6 Repeat Steps 3 through 5 so that the final response curve matches Response Curve,
When property aligned maximum allowable amplitude ratio above and below zero reference is approximately
7 (See Response Curve
Check all channels for same response, if response is not the same, adjust
for each
With the tuner set to an outside signal, observe whether or not the AFT locks in a black and white station and a station.
8 Note: If AFT is found to lock in but not perform the Burst Alignment. If AFT does not B/W or repeat this
AFT alignment.
Curve “A”
Response Curve
Figure