Sencore PS163 User Manual

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Fig. 11. Measuring phase shift between
signals.
DIVISION INSIDE OVAL
Sine
of
Angle
=
DIVISIONS
OUTSIDE
OVAL
2
Sine of angle = 5
Sine of angle = 5
Angle = 30°
VECTOR SERVICING
The use of a vector scope to service color television
receiver circuits is increasing in popularity. The vector-
scope along with a good color bar generator is a very
useful tool for troubleshooting and aligning the color
circuits. Proper phase shift of the 3.58MHz oscillator
bandpass alignment and frequency of the 3.58 are
some of the important points that can be checked
with the vector pattern.
The front panel VECTOR inputs of the PS163 make
vector servicing even faster and easier than before.
Here is the procedure for obtaining the vector pattern
on the PS163.
1. Connect a standard color bar generator such as the
Sencore Color King to the television receiver antenna
terminals and use the 4.5MHz sound carrier to prop-
erly fine tune the receiver.
2. Depress the VECTOR VERTICAL INPUT button
on the PS163. Connect the CHANNEL A probe to the
output of the R-Y amplifier or other R-Y test point
on the chassis. Connect the CHANNEL B probe to the
B-Y test point.
3. Adjust the A and B PPV PER DIV switches to the
same setting that gives a viewable pattern on the scope
screen. Slide SCALE ILLUMINATION switch near
the top of the PS163 to the VECTOR Position, to
illuminate the proper vector markings.
If the settings of the CHANNEL A and B PPV PER
DIV switches are not the same, a distorted vector
pattern will result. If the switches are set to different
settings, and the pattern is good, then a trouble exists
in the receiver. The photo in Fig. 12 is a good
vector pattern. The drawing is the ideal pattem.
Note that the good pattern is close to that of the
ideal.
Fig. 12. Ideal and typical Vector patterns.
THE IDEAL VECTOR PATTERN
Become familiar with the four important points to
look for in a good vector pattern.
1. The sides of the petals must be straight, extending
from the center of the pattern to the top of the petal.
They should not be bent or bowed or overlap each
other.
2. The tops of the petals should be flat and about
twice as bright as the sides of the petals.
3. The inner circle should be small with a dot in the
center. The sides of the petals should just meet at the
inner circle.
4. The pattern should be clean and as free from fuzz
as possible. Any fuzziness in the pattern is an indica-
tion of a misaligned 4.5MHz trap.
One word of caution here: a misalignment of the video
IF stages can cause the vector pattern to appear dis-
torted or incorrect. Be sure that the IF stages are
proper aligned before any alignment of the bandpass
amplifier or other circuits in the color section are per-
formed.
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Sencore PS163 Specifications

General

Brand	Sencore
Model	PS163
Category	Test Equipment
Language	English