Canon imagePRESS C800 Series, Troubleshooting Manual

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Chapter 1
1-9
1.1.1.3.4 Uneven density due to the areas on ITB where paper passes and does not passes
0031-6964
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Symptom
After 200,000 sheets or more of a certain width[a] of paper is fed, if a broader width[b] of paper is fed with a high density image, the symptom where the color
comes out lighter in the areas at the both outer sides of the width of the former paper[a] may occur. The arrow [c] indicates the feed direction.
The below figure shows an instance that A4 and 13 x 19 are fed.
Cause
The resistance in the area of ITB where paper passed consecutively becomes higher, so that toner transfers from the drum to ITB easier.
When a broader width of paper than that previously fed consecutively is fed, a difference is generated in ITB resistance between the areas on ITB where paper
passed and had not passed. Thus the toner amount put on ITB differs between the said areas, and that leads to the above mentioned symptom.
Service work
1) Have the customer log in from System Management Mode in user mode.
2) Go to Preferences > Paper Settings > Paper Type Management Settings, select an appropriate paper type from among the list, press "Duplicate" button and then
"OK" button.
3) Enter any name as the duplicated paper type and press "OK" button.
4) Select the paper type duplicated in the step 3) and press "Details/Edit".