STAR*TECH JOURNAL/MARCH 1983
3
PURITY, CONVERGENCE AND TRACKING
ADJUSTMENTS FOR WELLS-GARDNER
COLOR X-Y MONITOR
All the adjustments can be made while the monitor is mounted in the
game. Allow 15 minutes warm-up time before attempting these
adjustments. Remember to observe the precautions regarding high
voltages when you make any adjustments on this display.
A. Purity Problems
1. Preliminary
Turn the monitor so it faces north or south. In the case of cocktail
games, all adjusments should be made with the monitor facing up.
Then degauss the picture tube with a hand-held degaussing coil.
Enter the self-test mode and advance the screens until the horizontal
and vertical checkerboard pattern is displayed. Then rotate the
encoder wheel on the control panel of the game until only the green
pattern appears.
2. Green Purity Adjustment
Loosen the yoke-retaining clamp so that the yoke can move. Slide
the yoke toward the back. Now, remove the rubber deflection yoke
wedges. These are the small rubber wedges between the yoke and
the tube. These are glued to the tube, so you will probably have to
peel them off. These will be used later in the final dynamic
convergence procedure. Now, remove any glue that may be holding
the purity and convergence rings in place. These are 3 sets of 2 rings
each, located behind the yoke. The first set (the pair closest to the
front of the tube) are the purity rings, the second or center pair are
the red and blue convergence rings, and the last pair are the green
convergence rings. Working with one set of rings at a time, rotate
one or both rings in a line so that they face opposite directions from
each other. In this position, they are set for minimum deflection.
Slowly slide the yoke toward the front of the CRT until the
pattern displayed is an overall pure green. Tighten the yoke clamp
lightly, then rotate the yoke to level the pattern on the face of the
CRT.
3. Red and Blue Purity Adjustment
Turn the encoder wheel until only the red pattern is displayed, and
slightly readjust the yoke for a uniform and pure red. Then turn the
wheel to the blue pattern and adjust that the same way. Go back and
check the green and the red patterns, and check to be sure they are as
pure as you can get them. Some compromise will have to be made
here, as all 3 colors will probably not be pure, but get them as close
as you can. Now tighten the yoke in place, and you are ready to
make the fine purity adjustments. This is done by adjusting the
purity rings for the best overall purity of each color. When all 3
colors are pure, put a small amount of glue on them to keep them in
place.
B. Static Convergence Adjustments (Center Area)
1. Preliminary
Put the game into self-test mode and advance the screens until the
horizontal and vertical checkerboard appears. Advance the encoder
wheel until only the red and blue lines are displayed.
2. Convergence
Adjust the tabs on the center pair of adjusting magnets so that the
red and blue lines are superimposed on each other (Do this at the
center of the screen.) Next, turn the encoder wheel on the control
panel until the red, blue and green lines are displayed. Adjust the
tabs on the pair of magnetic rings closest to the neck PCB ( the green
convergence rings), so that the green line is superimposed on the red
~d blue lines. (Do this at the center of the sc~een.) At this point,
with all 3 guns on, the checkerboard pattern m the center of the
screen should be pure white. When this is completed, put a small
amount of glue on the rings to keep them in place.
C. Dynamic Convergence (Outer Area)
1. Preliminary
Put the game into self-test mode and advance the screens until the
horizontal and vertical checkerboard is displayed. Advance the
encoder wheel until the red, blue and green lines are displayed.
2. Convergence
Up/down movement of the yoke causes the outer edges of the screen
image to swivel clockwise or counterclockwise. Side-to-side
movement causes the lines at the outer edges to expand and
contract. Move the yoke in the up/ down and side-to-side directions
until the outer lines on the screen are pure white. Then secure the
defelction yoke by putting the rubber deflection yoke wedges back in
between the picture tube and the yoke's white collar. Secure the
wedges with glue or RTV, and then tighten all screws holding the
deflection yoke clamp and magnets in place.
D. Tracking Adjustments (Neck PCB)
1. Preliminary
Put the game into self-test mode and advance to screen #5 (seven
groups of colored bars of various intensities). Next, turn on all the
pots on the neck PCB to their full clockwise position. Tum the
brightness control to a level that clearly displays the fifth line from
the right of the center group of lines. If the sixth line from the right is
visible, reduce the brightness. If the fifth line from the right is not
clearly visible, increase the brightness. There are six pots on the
neck board - 3 for red, green and blue bias, and 3 for red, green and
blue drive. The bias pots are for controlling the low intensity color
mix, and the drive pots are for the high intensity color mix. When
properly adjusted, the color of a line should remain the same
whether it is bright or dim. In actual practice, a line that is bright
white will probably appear blue-white when the intensity is
decreased.
2. Bias Adjustments
Adjust the red, green and blue bias potentiometers until the fifth line
from the right (the lowest intensity line) is pure white. These pots
are labeled R bias, G bias and B bias.
3. Drive Adjustments
Adjust the red, green and blue drive potentiometers until the first
line on the right ( the high intensity line) is pure white. Drive pots are
labeled R drive, G drive and B drive. If you fmd it impossible to get
both the low and high intensity lines pure white, adjust for pure
white at the high intensity level, and just get the low intensity level as
close as you can.
This completes the alignment procedures for the Wells-Gardner
color X-Y monitor.
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Star*Tech Journal, Volume 5, Number 1, March 1983. Copyright 1983 by Star*Tech Journal Inc. All rights reserved. Star*Tech Journal is published 12 times a year. Address
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Contributing Technical Writers: Todd Erickson, Frank Becker, Mark "Beaf' Atteberry.