Midway 4-Player 25" Dedicated Video Game - Manual (Page 112)

Troubleshooting 6-10
Video Troubleshooting Table, continued
SYMPTOM CAUSE REQUIRED ACTION
• White areas at screen edges
appear tinged with color
• Dots at screen edges
appear oval 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.
Improper sync signals
1. Check to see if Video Board puts out type of
sync that your monitor requires.
2. Adjust sync for monitor you’re using: On SIO
Board, set DIP switch bank U12, switch 2. Off =
medium resolution (default); on = low resolution.
3. Verify that jumpers are set correctly for monitor.
4. If necessary, add or remove video sync jumper
at Sound I/O Board jumper block J2. With no
pins connected (or pins 2 and 3 connected),
board outputs positive sync. With pins 1 and 2
connected, board outputs negative sync.
Faulty wiring
1. Check connectors and cables for wiring
continuity. Video cables connect graphics card
to circuit boards, and then to video monitor.
2. Assure connection of all cabinet ground wires,
especially at video monitor chassis.
3. If you find faulty wiring, repair it.
Faulty monitor
circuitry
1. Check video monitor operation by connecting it
to working VGM (video game machine).
2. Assure that monitor is correct type for this VGM.
Monitors with wrong resolution can’t lock sync.
3. If you have wrong type monitor, replace it.
•
Video tears or rolls, or has
black bar down middle of
screen
• Video may appear as
colored bars of dashed lines
Electromagnetic
fields Move cabinet far away from machines,
appliances, or competitors’ VGMs.
Faulty wiring
1. Check connectors and cables for wiring
continuity from circuit boards to video monitor.
2. Repair faulty wiring.
• 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 (video game machine).
2. Enter Monitor Tests 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.