Quantum Data 801GC, 801GF, 801GX manual Outline0 and Outline1 contd

Outline0 and Outline1 — contd.

Test	Yoke tilt correction
Purpose	The horizontal axis of a displayed image should line
	up with the horizontal axis of your monitor. Any
	tilt is likely due to the yoke being rotated on the
	neck of the CRT. A rotated yoke makes any displayed
	image appear rotated.
Method	Place your monitor on a flat surface so the face of
	the CRT is perpendicular to the surface. Use a
	ruler or gauge to measure the height of each end
	of the image’s horizontal center line from the
	surface. The difference between the two readings
	should be within spec for the monitor. If it’s out
	of spec, the yoke needs to be adjusted. Loosen
	the hardware that clamps the yoke to the neck of
	the CRT and rotate the yoke until the line is
	horizontal. Tighten the yoke-clamp hardware.
Test	Yoke winding orthogonality check
Purpose	The horizontal and vertical deflection coils on the
	yoke should have their axes cross at exactly 90
	degrees. Improper orientation of the windings
	causes displayed rectangles to look more like non-
	orthogonal parallelograms. This type of defect is
	almost impossible to correct with adjustments. It’s
	usually easier to replace the defective yoke.
Method	First perform the previously discussed yoke tilt test.
	The vertical center line of the image should be
	perpendicular to the work surface. If the deviation
	is beyond spec, the monitor should be rejected and
	sent back for repair before the operator wastes time
	trying to magnet a defective yoke.

4-42 Chapter 4: Built-In Images Model 801GC, 801GF & 801GX¥Rev. X1