Midway Offroad Thunder, Operation Manual

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Troubleshooting 6-14
Video Troubleshooting Table, continued
SYMPTOM CAUSE REQUIRED ACTION
•
White areas at screen edges
appear tinged with color
•
Dots at screen edges
appear ovoid or cylindrical
Picture tube dynamic
convergence is out of
alignment
Have service bureau dynamically reconverge
monitor. This procedure requires removing and
repositioning yoke. Service bureau must follow
instructions from monitor manufacturer.
Faulty wiring
1. Check connectors and cables for wiring
continuity. Video cables connect computer to
circuit boards, and then to video monitor.
2. Assure connection of all cabinet ground wires,
especially at video monitor chassis.
Faulty monitor
circuitry
1. Verify that video monitor operates correctly by
connecting it to working VGM.
2. Assure that video monitor is correct type for this
VGM. Video monitors with wrong resolution can’t
lock sync.
Improper sync signals
1. Check to see if Video Board puts out type of
sync that your monitor requires.
2. Verify that jumpers are set correctly for monitor.
3. If necessary, add or remove video sync jumper
at MagicBus Board jumper block JP4. With no
pins connected (or pins 2 and 3 connected),
board outputs positive sync. With pins 1 and 2
connected, board outputs negative sync.
•
Video tears or rolls, or has
black bar down middle of
screen
Electromagnetic
fields Move cabinet far away from machines,
appliances, or VGMs (video game machines).
Faulty wiring
Check connectors and cables for wiring
continuity from circuit boards to video monitor.
•
Missing colors
Faulty monitor color
drive circuitry Verify that video monitor operates correctly by
connecting it to working VGM.
•
One color is dimmer or
brighter than others
•
Whites appear tinted
everywhere on screen
Maladjusted color
bias pots
1. Turn on VGM.
2. Enter Monitor Patterns Menu.
3. Watch Color Bars screen in mirror.
4. Adjust three bias pots for best colors. (Most
monitor neck boards include these pots.)
5. Also check White Screen. Touch up controls.
6. If whites still seem tinted, have service bureau
rejuvenate picture tube.
•
Picture is dim or faded
Maladjusted
BRIGHTNESS pot or
subnormal picture
tube emission
1. Watch Color Bars screen. Adjust BRIGHTNESS
and CONTRAST pots for greatest number of
grays. You’ll find these pots on Monitor Remote
Control Board, behind coin door.
2. If pots have no effect, have service bureau
rejuvenate picture tube.
•
Picture is too narrow
Maladjusted WIDTH
pot
Enter Monitor Patterns Menu. Watch Crosshatch
Screen while adjusting WIDTH pot for best
picture. You’ll find this pot on Monitor Remote
Control Board, behind coin door.