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Display Adjustments
DANGER
The display assembly contains high voltages and the
green wire in the display assembly is not at ground
voltage. Therefore, use extra caution when making
internal adjustments.
152
VIDEO ADJUSTMENTS
The three adjustments common to all display assemblies
are:
• The Brightness control on the control panel.
• The Contrast control on the control panel.
• The Brightness Limiter control on the display
assembly.
Brightness Limiter Adjustment
1.
2.
Turn the Brightness control on the control panel
fully clockwise.
Turn the Brightness Limiter control on the display
assembly until the retrace lines just disappear. See
the raster figure (156).
Note: Too much brightness could cause poor
focu~.
Contrast Control and Brightness Control
Adjustments
1.
Display Option
1
(Display Attributes) of the Display
Verification Menu of the Online Test (206).
2.
The pattern of H's around the display screen are
of both normal intensity and of high intensity .
. Adjust the Contrast control and the Brightness
control for the best display screen image.
Video Gain
On some display assemblies, this adjustment limits the
character brightness. Normally, use the Brightness
control on the control panel for attaining the best
display screen image. The video gain can correct the
horizontal or vertical intensity of a character.
151·153
153
VERTICAL AND HORIZONTAL ADJUSTMENTS
Vertical Adjustments
The vertical adjustments could interact. You should
adjust the vertical hold anytime the picture rolls before
you continue with the other vertical adjustments.
Vertical Hold
Adjust the vertical hold for a stable display (not rolling)
without display distortion (flat top).
1.
2.
3.
Place the Status switch in the Test position to
display the scan code, address, and 10 fields.
Observe the display screen while you turn the
vertical hold to its limit.
Set the vertical hold adjustment in the middle of
its range. Do not allow the picture to roll. If a
small adjustment causes the picture to roll up then
down, replace the display assembly.
Vertical Height
This adjustment controls the overall display screen
height. The nominal height should be
190
mm
(7.6 inches).
Vertical Linearity
This adjustment controls the uniform character height.
The vertical height and vertical linearity can interact.
Adjust for the desired result.
Linearity Phase
This adjustment controls the uniform character height
between the top of the screen and the bottom of the
screen.
Maintenance Procedures
5251 MIM
1-43
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