Wyse WY-60 Maintenance Manual page 62

The focus adjustment is labeled FOCUS VR201 on the terminal PCB.
Display test pattern M. Adjust VR201 until the characters halfway
between the center of the display and the bezel are distinct and
clear.
Linearity
The linearity adjustment is labeled VR303 on the terminal PCB.
Display test pattern M. Adjust VR303 until characters on the
bottom of the display are the same height as those on the top.
TEST PATTERNS
Two alignment test patterns are stored in read-only memory (ROM):
pattern M and pattern O. (A third pattern, the character
attribute pattern, is used for diagnostic purposes only.)
Pattern H
Pattern M helps you detect and correct linearity, brightness, and
focus.
See Figure 4-6.
Figure
4-6
Pattern M
Focus
Focus and Intensity Pattern
Full Bright
4-15