Midway Hydro Thunder, Operation Manual

Page: 101 / 105

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, change video sync jumper on
Diego Board. Refer to Wiring chapter for details.
•
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.
•
Picture is too short
Maladjusted HEIGHT
pot or damaged
vertical circuit
1. Enter Monitor Patterns Menu. Watch Crosshatch
Screen while adjusting HEIGHT pot for best
picture. You’ll find this pot on Monitor Remote
Control Board, behind coin door.
2. If pot has no effect, service vertical output circuit.
•
Picture seems shifted to one
side
Maladjusted
HORIZONTAL
POSITION pot
Enter Monitor Patterns Menu. Watch Crosshatch
Screen while adjusting HORIZONTAL POSITION
pot for best picture. You’ll find this pot on Monitor
Remote Control Board, behind coin door.
•
Keystone-shaped picture
Shorted turns in yoke
1. Substitute working yoke.
2. Have service bureau converge monitor.
3. Retest monitor.