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Subject: HIGH TONER DENSITY IN LOW HUMIDITY ENVIRONMENT
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Electrical
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General Information
Symptom:
Under low humidity condition such as during the winter, the toner density increases quickly within 1 K copies
after developer replacement. This results in high image density and possible dirty background. This is
particularly noticeable with black and cyan.
Cause:
Due to the drop in the charge of the developer over time, it is necessary to change the Vent if the developer
gamma surpasses a certain value to prevent the image density from increasing. However, the charge for this
type of toner has a tendency to decrease in high-temperature/low-humidity environments, therefore the
symptom occurs more frequently during the winter. Since the Vent cannot keep up with the speed with which
the charge drops, the image density rises over short periods of time.
Solution:
1. Replace the developer (all colors).
2. Adjust the toner density sensor initial setting until the image density is correct.
3. Access SP Mode; SP Adjustment: P. 16: Other SP Adjustment and set NO. 1 from 00000 to 00001.
Reason for Alteration
The above SP Mode turns on the Vent (Correction by number of scans) for the toner density control. When this
correction is turned on, the Vent decreases by -1 every 100 scans and ends after 600 scans/-6. However, for
cyan the correction is only up to 500 scans/-5. All colors are controlled separately.
Note
1.
It does not matter when the Vent is turned on after the developer has been changed. The result will be
same if it is done within 100 scans after toner density sensor initial setting.
2.
At the time of toner density sensor initial setting, the correction counter is reset to 0.
3.
If the Vent correction is turned on without developer replacement, there is the possibility that the image
density will gradually become lighter.
4.
In a high-humidity environment, there is a possibility of over-correction (low toner density leads to low
image density), therefore turn this Vent correction off.
Savin Corporation
Technical Service Operations - P.O. Box 10270, Stamford, Connecticut 06904 --- (203) 967-5000
Model - Product/Serial Numbers Affected Modification Schedule
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S D C 2 0 6
Field Engineering Bulletin
Digital Color Series
BULLETIN NO: SDC206/206E - 006 DATE: 1 O/22/97
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