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June 2005 © TOSHIBA TEC e-STUDIO281c/351c/451c ADJUSTMENT
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3.5 Image Quality Adjustment (Copying Function)
3.5.1 Automatic gamma adjustment
When the reproduction of gradation is not appropriate, the gradation reproducibility of all colors Y, M, C
and K can be corrected by performing this automatic gamma adjustment. In case the gradation repro-
duction of the image checked is not satisfactory, make this adjustment as described below at parts
replacement.
(1) When unpacking or any of the following parts has been or replaced, be sure to make this adjust-
ment:
• Laser optical unit • Photoconductive drum • Developer material
• Main charger wire • Main charger grid • Transfer belt
• 1st transfer roller • Drum cleaning blade • Drum cleaner brush
• Image Quality sensor
(2) When any of the following parts are replaced or adjusted, make a copy and check the image to
determine if adjustment is necessary:
• 2nd transfer roller
Notes:
1. Be sure that this adjustment be made after performing the image adjustment in "3.3 Adjust-
ment of Image Quality Control" and "3.4 Image Dimensional Adjustment".
2. Normally, only the adjustment of color/black integrated pattern is needed. When the adjust-
ment of "3.5.12 Beam level conversion setting" is made, color pattern and black pattern need
to be adjusted individually.
<Adjustment Mode (05)>
Code Item to be adjusted Contents
1642
(1643)
(580)
Automatic gamma
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] but-
ton to output a “Patch chart for gamma adjustment”.
Pattern No. Pattern Remarks
4 Color/black integrated When performing code 1642
10* Black When performing code 580
5* Color When performing code 1643
* This adjustment is performed only when "3.5.12 Beam level conversion
setting" is performed. Usually, only the adjustment with the color/black
integrated pattern (05-1642) is performed.
3) Place the patch chart for adjustment printed in step (2) face down on the
original glass. In the cases of patterns 4 and 5, place the chart aligning its
side with 2 black squares against the original scale.
In the case of pattern 10, place the chart aligning its black side of the grada-
tion pattern 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.).
5) When the adjustment has finished normally, “ENTER” is shown. Press the
[ENTER] 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.