E-020 sub code 0081.
E-020 stands for a drum / developer related error. Sub code 0081 stated that the P-SEN-P is less than 255 when a base (drum face) of patch detection is read out. In other words patch read is too low when primary is charging drum. When troubleshooting these type of codes (E-020's) most technicians will try seeing a patch being developed on the ITB belt. In one case there were no patches being developed on ITB. No patch was due to the fact that the primary never came up to proper voltage which caused the machine to never turn on the laser. No laser no patch.
You can check the P-SEN-P reading in service mode Copier / Display / Dens / P-SEN-P.
If value is less than 255 then go to service mode level two Copier / Display / Dens / P-LED-DA if reading is 90 or above then patch sensor is dirty or scratched.
If reading is below 90 then drum unit is bad.
In this case, it was found that P-SEN-P had a reading of 225 and P-LED-DA with a reading of 170.
Replaced the patch sensor and problem was resolved. --------------------------------------------------------
Level 1
DENS-Y/M/C/K
Use it to check the computed value of the density (Y/M/C/K) of the patch formed on the photosensitive drum. (indicates the discrepancy from the target value in %) The value is updated when the machine executes toner supply operation after the main power switch is turned on.
Optimum:-25 to +25
P-SENS-S
Use it to check the value (S wave) detected of the intensity of light from the background (drum) of patch image sensor.
DRM-LIFE
Use it to check the age of the drum unit. Indicates how much it has been used in %.
Optimum:0 to 100 (unit: %)
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Level 2
DENS-Y/M/C-H
Use it to check the history of measurements taken by the ATR sensor (Y/ M/C; latest 8 measurements).
DS-S-Y/M/C/K-H Use it to check the history of the results of detection of patch images (Y/M/C/K; latest 8 result).
P-LED-DA
Use it to check the D/A settings of the LED for the path image sensor.
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Checking the Soiling of the Window
When the window of the light-emitting/receiving segment of the patch image read sensor becomes soiled with stray toner, the machine will not be able to accurately measure the density of the patch image. To avoid the problem, the machine checks the patch image read sensor for soiling. While initial multiple
rotation is under way, the machine measures the light from the surface of the drum without depositing any toner on it (drum background measurement); it will assume that the window is soiled if the measurement is lower than a specific level (COPIER>DISPLAY>DENS>P-SENS-P), thus indicating an error code (E020-0081) and stopping its operation.
Although the machine does not check the ATR sensor for soiling, the sensor is equipped with a shutter to prevent soiling; the shutter opens only when the ATR sensor measures the developer density on the developing cylinder and remains closed at other times.
ATR Control
The machine executes ATR control to keep the density (ratio of toner/carrier) inside the developing unit to a specific level, which otherwise would change over time.
<Particulars of Control>
The machine is not equipped with a means (sensor) of directly measuring the level of toner inside the developing unit.
In its place, the machine forecasts the consumption of toner with reference to video count data to make up for the consumption of toner. The toner supply amount computed from the video count data is corrected at such times as programmed: the machine uses the difference in potential between the primary charging bias and the developing bias to form a patch density on the photosensitive drum.
It reads the density of the patch using the patch image read sensor, and compares the result against the density target value to increase or decrease the toner supply amount.
If the density of the patch image changes because of changes in the developer characteristics, the machine will not be able to keep the density of the developer inside the developing unit to a specific level, which would cause the toner to move astray inside the machine or carrier to stick to the drum.
To prevent such a problem, the machine corrects the density target value at such times as programmed, thereby keeping the density of developer inside the developing unit to a specific level. (In the case of Y, M, or C, the machine uses the density of the developer measured by the ATR sensor; in the case of Bk, on the other and, the machine corrects the density target value based on the reading of the counter designed for the developing unit (Bk; i.e., how may sheets have moved past it).
