Dot-Matrix Print Density Problems On an impact (dot-matrix) printer, alternating light and dark print is most commonly caused by which condition?

Introduction / Context:
Dot-matrix printers use a moving ribbon and pin head to strike dots onto paper. Print quality issues often trace back to consumables (ribbon) or mechanics (tractor feed). Recognizing the signature of specific faults speeds repair and reduces downtime.

Given Data / Assumptions:

• Printer uses a ribbon cartridge with driven and take-up mechanisms.
• Symptoms: alternating bands of light and dark text or graphics across the page.
• Paper feed works otherwise normally.

Concept / Approach:

If the ribbon does not advance smoothly, some segments become ink-depleted while others are fresh. As the head prints, density alternates between light (overused ribbon area) and dark (fresh ribbon segment). This yields periodic banding consistent with ribbon slip or jam.

Step-by-Step Solution:

Verification / Alternative check:

A test page after installing a new ribbon should eliminate alternating light/dark bands, confirming ribbon advancement was the cause.

Why Other Options Are Wrong:

Erratic paper feed causes vertical misregistration or skew, not regular density cycles. Misalignment affects dot placement rather than density bands. Overheating is rare and typically causes shutdown/errors, not patterned density fluctuations.

Common Pitfalls:

Confusing dirty platen or head with ribbon problems; always check consumables first.

Final Answer:

Erratic ribbon advancement