TECHNICAL SERVICE BULLETIN
BULLETIN NUMBER: AFICIO COLOR 5106/5206 - 018 12/22/97
APPLICABLE MODEL: AFICIO COLOR 5106/5206
SUBJECT: LOW HUMIDITY EFFECT ON TONER DENSITY
SYMPTOM:
SC 374/377 and/or over toning.
Under low humidity condition’s usually during the winter, the toner density rises quickly after developer
replacement (within 1K copies) and causes dirty background. This is particularly noticeable with black and
cyan.
CAUSE:
The charge on the developer over time drops, and it is necessary to change the Vcnt if the developer
gamma surpasses a certain value. This is to prevent the image density from increasing. However, the
charge for this type of toner has a tendency to plummet in high-temperature/low-humidity environments, so
this problem occurs more frequently indoors during the winter. Since the Vcnt 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. Follow the developer replacement procedure according to the FSM.
3. Access SP Mode; SP Adjustment: P. 16: Other SP Adjustment and set NO1 from 00000 to 00001.
The above SP Mode enables the Vcnt Correction by number of scans for the toner density control. When
this correction is turned on, the Vcnt decreases by -1 every 100 scans and ends after 600 scans/-6.
However, for cyan the correction is only up to 500 scans/-5.
Note
1. It does not matter when the Vcnt is turned on after the developer has been changed. The result will
be the 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 Vcnt 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) so please turn Vcnt correction off.
CUSTOMER SERVICE GROUP
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