Yamaha CL3 Service Manual page 144

CL3/CL1
1-18. LCD Test
Contents: LCD display test
Among patterns of the LCD screen display, the
pattern 1) should be repeated at 3-second intervals
and 2) to 9) patterns at 5-second intervals. Check
this visually.
While the touch panel is pressed, the current screen
is kept as it is.
After checking, select the result as [OK] or [NG],
using the dialog box of the test program.
Example of executing screen
Input the check result using the dialog box as shown below.
1) Model name display
Checks if the displayed model name is correct.
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2) H character display
Check for distortion in vertical and horizontal directions
and with the frame (whether or not "H"s are clearly seen
in it).
3) Color bleeding and unstable display
As "O"s appear at both sides and "X"s in-between, check
that characters are stable, "O"s are in place and the color
is free from bleeding. The characters and background are
displayed in white, black and gray with slight variation.
4) Color box
The color changes in gradation from the right to left
growing into black.
Check that the colors (5 x 4) other than black are
displayed in gradation properly.