Ricoh M0A0 Service Manual page 326

7.Detailed Descriptions
LED Head
Each LED head has 26 LED chips on board, and each chip has a line of LEDs 8mm in length.

If a vertical line 8mm in width appears on the image parallel to the direction of paper feed, it may be caused
by a broken LED chip.
LED Positioning
The LED head contacts the spacer on the drum in order to hold and adjust the correct focal distance from the PCDU
(slide-and-move method).
Image Position Adjustment
You can adjust the printing position from each tray with [Registration] in Menu.
At this time, the following controls are done as the adjustment in the machine;
Horizontal Scan: Adjusted by moving the whole image position.
Vertical Scan: Adjusted by changing the light-emission timing.

There is no mechanical adjustment, unlike laser writing.
Writing is applied across the extent of the LED head in the horizontal direction. So, if you want to adjust to
printing position to an area that is outside the one that is within the setting range in [Registration], adjust the
paper position in the feed tray.
To adjust the paper position in the feed tray, you can adjust horizontal registration by loosening the screws on the
bottom of the tray, and then moving the holder to right or left (up to 2mm).

When at the default (±0) position, the holder position is the triangle marked area [A] in the picture below.
LED Light Volume Adjustment
An EEPROM on the LED head contains data which controls the light intensity of each element. There is no adjustment.
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