CompTIA A+ Core 1 (220-1201)Hardware and Network TroubleshootingMedium
A client's laser printer produces printouts with a repeating dark smudge that appears at regular intervals down the entire length of every page. What is the MOST likely cause?
- AIncorrect paper type selected
- BLow toner level
- CA loose USB cable
- DA damaged or dirty drum unit
Show answer & explanationAnswer & explanation
Correct answer: D. A damaged or dirty drum unit
A defect or debris on the imaging drum creates a mark that repeats at a fixed interval matching the drum's circumference, appearing consistently down the length of every printed page.
Why the other options are wrong
- A. Wrong paper settings cause jams or quality issues, not periodic marks.
- B. Low toner typically causes faded or streaky prints, not a repeating spot pattern.
- C. A loose USB cable would cause print failures or garbled data, not a physical mark pattern.
Laser Printer Drum Defects
The imaging drum in a laser printer transfers toner to paper; scratches or debris on it cause a mark that repeats at a fixed interval equal to the drum's circumference.
- Repeating marks = drum defect, spacing reveals drum size
- Low toner causes fading, not repeating marks
- Drum is often part of a replaceable toner cartridge unit
Memory trick: 'Repeats Reveal the Drum.'