Symptoms
- Fuzzy dark blob in the same spot on every input
- Spot doesn't move when you move the projector
- Shadow gets bigger over time
- Spot visible mainly on bright scenes
Likely causes
- CommonDust on the lens or internal opticsA speck of dust on or near the lens casts a soft shadow that's most visible on plain bright backgrounds.
- PossibleDebris inside the light pathDust can enter through vents and settle on internal mirrors or panels.
- PossibleCondensation inside the lens assemblyMoving a cold projector into a warm humid room can cause temporary internal fogging.
- Less commonPanel or DMD chip defectA fixed dark pixel cluster that doesn't relate to dust suggests a hardware defect.
What to do
- Clean the outer lens gently with a dry microfiber cloth or lens-cleaning wipe; never spray liquid directly on it.
- If the spot remains, let the unit run for 20–30 minutes; condensation-related shadows often clear as it warms.
- Check and clean the air filter, since a clogged filter lets more dust circulate inside.
- Project a plain white or gray image to see the spot most clearly and note its exact position.
- Avoid using compressed air inside the unit yourself; it can push dust deeper onto sensitive optics.
- If the spot persists after cleaning the outer lens and running it warm, it needs professional internal cleaning.
Tools and parts
- Microfiber cloth
- Lens cleaning wipes
When to call a pro
Internal dust or a suspected panel defect needs a technician; opening the optical block yourself risks worse damage.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.