Answer
Mar 03, 2024 - 05:48 PM
Light or blank areas on prints are most often caused by some toner puffing up onto the slit glass of the ROS Laser Unit. Dirt/toner on the slit glass will cause the laser to be weak when it shines on the drum... so the image will be lighter in the affected area. If the laser gets blocked completely, the result is a blank area that runs from the lead edge of the paper to the trail edge. The laser slit glasses are very difficult to see unless you take the Drum Drawer out completely and peer in with a flashlight. You must get up inside there very gently with a lint-free swab. You need a relatively long stick with a soft cleaning swab at the end, but be gentle... the glass up there is fragile. We offer a really good tool for gently cleaning the ROS Slit Glasses on this series. (DC250RSGCT - ROS Slit Glass Cleaning Tool). It comes in two parts. When you join the two halves, the handle is nice and long, and it comes with extra cleaning nibs. If cleaning the slit glass resolves the symptom, you will also want to address why toner puffed up on the slit glass in the first place. Usually it happens because the mylar seal blade that is adhered to the top cover of the developer unit gets damaged or it starts to curl away from the drum as it ages. So check the affected color's developer unit to see if the mylar blade looks curled or damaged. If so, buy the DC250DSBK - Developer Seal Blade Kit. Read the information on the listing because there are some potential pitfalls when you go to replace the seal blades.
Two other possibilities are less likely ... but if cleaning the slit glass does not solve the problem, here is what else to look at.
If the problem is in Magenta, Cyan, or Yellow only, you can check if it's a drum cartridge problem by swapping the affected color drum cartridge with one of the other colors. If the symptom follows the drum cartridge, replace it.
Finally, check the developer mag roller... Remove the drum cartridge and have a look at the developer and toner on the magnetic roller where it faces the drum. It should have a nice, even brush of developer/toner all the way across from front to rear. If there is a bald spot on the mag roll, there might be debris inside the developer unit, trapped behind the developer metering blade. In that case, you would need to clean the unit out and replace the developer powder.
Two other possibilities are less likely ... but if cleaning the slit glass does not solve the problem, here is what else to look at.
If the problem is in Magenta, Cyan, or Yellow only, you can check if it's a drum cartridge problem by swapping the affected color drum cartridge with one of the other colors. If the symptom follows the drum cartridge, replace it.
Finally, check the developer mag roller... Remove the drum cartridge and have a look at the developer and toner on the magnetic roller where it faces the drum. It should have a nice, even brush of developer/toner all the way across from front to rear. If there is a bald spot on the mag roll, there might be debris inside the developer unit, trapped behind the developer metering blade. In that case, you would need to clean the unit out and replace the developer powder.
