Brother MFC-9420CN Service Manual page 237

<When turning the power switch ON while holding down the * and 2 keys>
Function
This function is to print the test print including the grid pattern of one or two colors
(R, G, B), full color stripe pattern, white pattern, 100% duty pattern, 50% duty pattern,
25% duty pattern and 6% duty pattern.
Operating Procedure
(1) Press the 6 key in the initial stage of the engine service mode.
The "31 GRID PRINT / <▲ 2 3 4 5 6 7>" appears on the LCD.
(2) Select the pattern you want to print with using the 4 or 5 key.
(Refer to the sample as shown in the
Pattern 1: Grid pattern
Pattern 2: Full color stripe pattern
Pattern 3: White pattern
Pattern 4: 100% duty pattern
Pattern 5: 50% duty pattern
Pattern 6: 25% duty pattern
Pattern 7: 6% duty pattern
After selecting the pattern, press the 6 key.
(3) When selecting Pattern 1, 3, 4, 5, 6 or 7, select the color you want to print with using the
4 or 5 key and press the 6 key.
When selecting Pattern 2, proceed to Step (4).
(4) The machine prints the selected pattern continuously after warming-up.
(5) Press the 3 key so that the machine stops printing.
(6) Press the 3 key again, and the machine returns to the initial stage of the engine service
mode.
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