Quantum Data 801GC, 801GF, 801GX manual

Test	Display size correction
Purpose	A too-large active video size adjustment on a monitor
	may cause information to be lost around the edges
	of the screen. A too-small active video size adjustment
	may make some displayed information hard to read.
	The correct size is needed to obtain the correct aspect
	ratio. You need the correct aspect ratio to get round
	circles and square squares.
Method	First you need to know the correct physical size of
	the active video area for the display. This information
	usually is given in a display’s spec sheet or service
	manual. The size should match the sizes in the format
	you’re using. The size setting of the current format
	can be checked using the Format test image.
	Place a ruler or gauge along the horizontal line of
	the image and adjust the monitor's horizontal size
	control until the distance between the endpoints
	matches the specified value.
	Move the ruler or gauge to the vertical line and
	adjust your monitor's vertical size control until
	the distance between the endpoints matches the
	specified value.
Test	Parallelogram distortion check
Purpose	Parallelogram distortion is very difficult to correct
	with magnets because the correction often causes
	barrel distortion. Therefore, you should decide
	early whether your monitor meets this spec. The
	problem usually can be traced to the improper
	winding of the yoke coils. If the problem isn’t too
	severe, it may be corrected by adding or adjusting
	magnets on the yoke. However, if the distortion
	is excessive, it may be an indication of a defective
	yoke which cannot be corrected with magnets.

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