Canon MP640 Service Manual page 47

4-3) Rotate the Easy-Scroll Wheel counterclockwise step by step. The LCD is divided into 6 segments, representing each step.
The color of a segment corresponding to the step changes from green to blue. If the wheel is rotated clockwise before
counterclockwise round completes, the color of segment(s) corresponding to the number of steps the wheel is rotated
clockwise returns to green. If the wheel keeps rotated counterclockwise over 1 round (6 steps), the color of segment(s)
corresponding to the extra number of steps returns to green, starting with the "Start" segment in the figure below.
4-4) When the Easy-Scroll Wheel is rotated counterclockwise 1 round (6 steps, and all the segments are in blue), press the OK
button. The color pattern is displayed on the LCD. If there is any segment that is not in blue when the OK button is
pressed, the display remains unchanged.
5) Transparent pattern display check
5-1) Press the OK button. "OK1" in white is displayed on the black background. If the result is not good, "NG1" in black is
displayed on the white background (transparent color) immediately after "OK1." Wait for approx. 2 seconds.
5-2) Press the OK button. "OK2" in black is displayed on the white background. If the result is not good, "NG2" in white is
displayed on the black background (transparent color) immediately after "OK2."
5-3) Press the OK button. The machine returns to be ready for selection of another function ("Service Mode Idle" is displayed
on the LCD).
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