Image Quality Adjustment (Copying Function) - Oki MB760 Service Manual

4.2

Image Quality Adjustment (Copying Function)

4.2.1 Automatic gamma adjustment
When the reproduction of gradation is not appropriate, the gradation reproducibility can be
corrected by performing this automatic gamma adjustment. In case the gradation reproduction
of the image checked is not satisfactory, make this adjustment as described below at parts
replacement.
When unpacking or any of the following parts has been replaced, be sure to make this adjustment:
• Drum unit
• Transfer belt unit
• SRAM board (SYS board)
• PU board
• HDD
Notes:
Be sure that this adjustment be made after performing the image adjustment in  P. 4-2 "4.1.2
Image Dimensional Adjustment".
<Procedure>
(1) While pressing [0] and [5] simultaneously, turn the power ON. → Adjustment Mode
(2) Select the A4/LT drawer. Key in the pattern number and press the [FAX] button to output a "Patch
chart for gamma adjustment".
<Adjustment Mode (05)>
Pattern No.
10
(3) Place the patch chart for adjustment printed in step (2) face down on the original glass.
Place the chart aligning its side with a black square against the original scale.
(4) Key in a code and press the [START] button.
→ The scanner reads the chart automatically and performs automatic gamma adjustment
calculation (approx.30 sec.).
<Adjustment Mode (05)>
Code Item to be adjusted
7165 Automatic gamma
adjustment
(5) When the adjustment has finished normally, press the [OK] button to have the adjustment
results reflected.
(To cancel the reflection of adjustment results, press the [CANCEL] button.)
In the case of an abnormal ending, "ADJUSTMENT ERROR" is shown.
Press the [CANCEL] button to clear the error display. When it is cleared, the control panel
display will return to the ready state. Then, check if the patch chart on the original glass is
placed in the wrong direction or if it is placed inclined on the original glass, and then repeat
step (3) and afterward.
45641001TH Rev.1
Pattern No.
Black When performing code 05-7165
When the reproduction of gradation is not appropriate, the
gradation reproducibility can be corrected by performing
this automatic gamma adjustment. The result of 7165 is
applied to all paper types.
Remark
All paper types
Contents
Oki Data CONFIDENTIAL
Paper type
4-4 /