Midway 16-20044-101, 16-20040-101 manual Horizontal

Video Troubleshooting Table, continued

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

Troubleshooting 6-14