Definitive CRT Projector Setup Guide

Tilt

Here you can see the red tube is way off of the green line in a vertical direction. When adjusting tilt and skew, concentrate on the line running down the middle of the screen, both vertically and horizontally. Use that line only (feel free to use the crosshair test pattern) to set the tilt and skew.

Bow

As with the tilt and skew commands, use the center horizontal and vertical lines in the middle of the screen to set the how control. Here’s two pix that show the range of the bow control:

Amplitude

As with the green, the red amplitude control changes the height and width of the red tube grid as compared to the green tube. You want the height and width of the red tube to match the green. The below pix show too little and too much height on the red tube:

Linearity

You are now adjusting the size of the top squares as compared to the bottom squares, or the left squares to the right side ones. Use the linearity control in conjunction with the amplitude control to overlap all edges to the green tube. Shown below are top and bottom linearity extremes to show what the control does. Left and right linearity works in a similar manner to the top and bottom controls:

Note that having settings quite a bit off the O mark is normal for the red and blue convergence controls to get them to overlap with the green.

Linearity Balance Controls

To further confuse the end user, NEC has 4 linearity balance controls for extra fine tuning of the linearity controls. Under normal flat screen installations, the linearity balance controls can be set to 0, but under certain circumstances, some fine tuning of these controls will bring the image into perfect convergence. The two pictures below show when too much linearity balance is used on the left side of the screen, pushing the red vertical lines to the left and right of the green reference grid:

The linearity balance controls affect the midpoint between the center and edges of the image rather than the edge or center of the grid.

Keystone

To make adjustments easier, the keystone adjustments are separated into the 4 sides of the set. Press the ‘ctrl’ and appropriate arrow button at the same time to change the side that the keystone adjustment is affecting. Here we are adjusting the bottom keystone as indicated by the solid arrow pointing at the bottom of the image:

In this case, good keystones is achieved at +42:

Pin-Cushion

As with the keystone command, the ‘ctrl’ button and the arrow buttons will adjust one side at a time. The range of the pin-cushion control is shown below:

Proper pin-cushion is achieved at about +5 in this case: