This article explains what to do if you see sets of dots appear on your printouts. This print quality issue is known as traffic lighting, and can be identified as follows:
In a colour print, sets of all four colours appear: black (K), cyan (C), magenta (M) and yellow (Y), also known as CMYK dots.
In a black & white print, there will be single dots of black only.
Traffic lighting can be caused by installing a toner cartridge incorrectly, where the locking mechanism scratches the drum of the photoconductor unit (PCU). It can also indicate a problem with the PCU itself, or with a hardware compnent.
Examples of print quality issues indicating a traffic lighting problem (click on an image to view an enlarged version).
Figure 1: Sets of CMYK dots appear in a single column.
Figure 2: Enlargement of Figure 1, with the CMYK dots circled in red.
Figure 3: Enlargement of CMYK dots. Note the four colours in each set of dots, in the order Black, Cyan, Magenta and Yellow.
In a Black & White print, only a black dot would appear.
Figure 4: Example of severe traffic lighting where the CMYK dots appear in a random pattern rather than in a single column. Note that your print sample may not show as many dots as this.
Now proceed to Step 3 to remove and check the PCU. You will need to replace the PCU to resolve the print quality issue.
If the distance is not around 51mm, the issue may be caused by another part. Proceed to Step 3 below to remove and check the PCU, and if the PCU is scratched or otherwise damaged then contact Epson for further advice.
If the dots do not appear in a single column, as shown in Figure 4:
Count approximately how many sets of dots appear on the page.
If there are six or more sets of dots, or if the problem is getting worse over time, there may be a problem with both the PCU and the developer rollers, or another hardware component.
If so, contact Epson as your printer may require a service.
You will need to replace the PCU as well to resolve the print quality issue, but any hardware issues must be resolved first. Do not replace the PCU until the printer has been serviced.
The PCU is a user-replaceable, consumable product.