Pincushion Adjustments; North-South Pincushion - Zenith Z-100 PC series Service Manual

3. Adjust R7703 for the best overall focus. Check
the center, top center, bottom center, left center,
and right center areas of the display for good
focus.
4. Verify acceptable overall focus using the fill
screen test with such characters as
@
and
#.
Pincushion Adjustments
The following sections contain procedures for per ­
forming the various pincushion (PIN) correction ad ­
justments. Because this monitor incorporates the
new flat technology CRT, these adjustments are con ­
siderably more involved than those for a monitor hav­
ing a conventional CRT.
NOTE: Read this procedure thoroughly before at­
tempting to perform any PIN adjustments. The con­
trols you will be adjusting are interactive; that is,
changing one control may make it necessary to go
back and change another control until the settings
are optimized. For this reason, perform these adjust ­
ments in the order in which they are presented.
North-South Pincushion
The north-south (N-S) pincushion adjustments con­
trol the symmetry of the top and bottom halves of the
display. To adjust the N-S PIN:
1. Display a crosshatch pattern in the 480-line
mode.
2. Locate the horizontal line nearest the top of the
display.
3. Adjust the north level control (R7436) to reduce
any PIN distortion at the center of this line. That
is, use this control to reduce any bowing in the
middle portion of the line.
4. Adjust the south level control (R7434) to reduce
any PIN distortion at the center of this line. That
is, use this control to reduce any bowing in the
middle portion of the line.
5. Adjust the north phase control (R7435) to obtain
the straightest possible line. Re-adjust the north
level control and the north phase control in turn
until the straightest line with minimum PIN dis ­
tortion results.
6. Adjust the south phase control (R7433) to obtain
the straightest possible line. Re-adjust the south
level control and the south phase control in turn
until the straightest line with minimum PIN dis ­
tortion results.
7. Adjust the N-S trap control (R7430) to eliminate
trapezoidal distortion in the display. Use the
edges of the monitor bezel as references to ob­
tain the most symmetrical display possible.
8. Adjust the N-S parallelogram control (R7431) to
eliminate parallelogram distortion in the display.
Use the edges of the monitor bezel as refer­
ences to obtain the most symmetrical display
possible.
9. Use appropriate software to fill the screen in the
480-line mode.
10. Adjust the N-S crossover zero control for mini ­
mum horizontal line separation across the cen­
ter of the display. The resulting display should
show fairly uniform horizontal line separation
throughout the display.
11 . Use both the crosshatch pattern and the fill
screen test and verify that the N-S adjustments
are correct. Repeat steps as needed to obtain
the best possible display.
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Page
4-8
Adjustments
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