6.0 TELEVISION RECEIVER ALIGNMENT USING
THE MODEL 415
It is the purpose of this section to outline a
standard approach for the various alignment
functions. First,
it is important that the tech-
nician develop confidence in his equipment
and procedures. Next he must be able to in-
terpret the response patterns obtained and
decide which receiver sections require align-
ment and the extent of the required alignment.
In some repair cases all that is required is that
the technician satisfy himself that receiver
alignment is not the basic problem (alignment
verification) before he proceeds further in
analyzing the set. Again, confidence in the
procedure is a must.
The technician must also realize that align-
ment alone is not the universal cure for poor
picture quality. Before he evaluates the effect
of alignment on the picture quality he must be
sure that the convergence, purity, focus and
high voltage regulation are properly set, and
that the set has been properly degaussed.
He should also eliminate the possibility
of
interference from other test equipment.
The following outline will be used:
6.0.l Connect the Channel 4 or Channel
10 signal
from the 415 to the antenna terminals of the
television receiver. Set the
r-f cable terminat-
ing pad switch to the 300-ohm position. Apply
bias as required to the tuner, i-f and chroma
sections.
6.0.2 Observe the
i-f alignment at the video detector
and the chroma alignment at the output of the
bandpass amplifier or at the demodulator in-
put and compare them to the manufacturer's
curves.
6.0.3 Based on the results obtained in 6.0.2 the tech-
nician will decide if touch-up alignment or
complete realignment is required. In some
cases, Step 6.0.2 will indicate that alignment
is not required.
6.0.4 A touch-up alignment procedure
will be out-
lined.
6.0.5 A detailed alignment procedure will be out-
lined.
6.0.6 Actual alignment procedures of various tele-
vision receiver manufacturers will be included.
These will be accompanied by detailed in-
structions on how to use the Model 415 to
perform the indicated alignment steps.
6.0.7 A condensed work guide will be outlined for
reference. This guide will include reference to
instruction paragraphs in the manual for a
parf.cular task as well as a standard operat-
ing procedure for setting up and performing
the task.
48
6.1
SIMPLIFIED PROCEDURE FOR DIAGNOSING
NEED FOR ALIGNMENT
(The test set-up of Figure 5.2 and the set-up
instructions of Par. 5.2 apply for the following
procedures.)
6.l.l Refer to the manufacturer's service manual or
the SAMS instructions. Read the complete
alignment section. Note the location of all
signal injections, bias and signal output
points, particularly for the specific alignments
to be performed. Note the requirements, if
any, for special load blocks
pr detector cir-
cuits. Two i-f load blocks are included with
the Model 415 accessories and the PR-151 De-
modulator Probe is adequate for all r-f, i-f and
video/chroma demodulator requirements. The
75/300
O switch on the r-f cable terminating
pad eliminates the need for generator-to-
antenna matching networks. A IO K ohm iso-
lating resistor is included in
1he direct cable
furnished with the 415, so that no isolating
resistor is required when connecting to the
video detector test point.
6.1.2 Check the bias requiremnts for overall align-
ment (input at antenna). Preset the 415 bias
supplies to the approximate voltage require-
ments using the VTVM. Connect the bias volt-
ages at the indicated points. An r-f age and i-f
age bias are usually specified. Use the 0-25
Volt supplies for these applications. If a color
set is being evaluated, locate the color killer
bias point and apply the specified bias. (This
is usually specified in the chroma alignment
section.)
6.1.3 Connect the direct cable to the specified video
detector test point.
6.1.4 Connect the PR-151 Demodulator Probe to the
chroma bandpass test point. This is usually
at the output of the bandpass amplifier. Note
the specified position of the color level and
brightness controls of the television receiver
and set them accordingly.
6.1.5 Set the IF· RF -VIDEO ATTENUATOR control
to minimum (maximum counterclockwise).
6.1.6 With the impedance selector switch of the r-f
cable termination in the 300-ohm position, con-
nect to the antenna terminals of the receiver.
6.1.7 Set SWEEP WIDTH at maximum. Turn on
ADJ PIX (39.75) and ADJ SND (47.25) markers
and use MARKER AMPLITUDE control to set
marker amplitude as desired. Using the
CENTER FREQUENCY adjustment, center the
sweep on the oscilloscope screen as in Figure
5.3.
6.1.8 Set the channel selector of the television re-
ceiver to Channel 4 and set the FUNCTION
switch of the 415 to the CH 4 position. (Chan-
nel
10 may be used if Channel 4 is not con-
venient.)
I
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