Projector image issue: Green and purple shadows/edge lining on projector images

[HigherEdAV]

One of the projectors in a classroom of mine has a discoloration on the edges of objects. For instance, black text on a white background appears normal but with a thin upper edge/shadow above the black that is purple and a lower one that is yellow.

 

Any ideas what this could be?

I've adjusted the focus and sharpness to no avail.

 

Thanks

[thimon]

To rule out it's the cable, directly plug a laptop into the back of the projector with VGA / HDMI. Same results?

[robyholmes]

Purple and yellow 'Blobs' are often dust on the lens inside the projector. You have a few choices:

- Send it away for cleaning

- Clean it yourself

- Replace

 

We avoid option 1 and 2 as 1 is expensive and you have mixed results. 2 is complex and often results in other issues once you start taking it apart. Replacing it ideally with a touch screen is the best long term option but you need the funding to do it.

[colly72]

We've found that it's sometimes a dodgy faceplate connection. As @thimon suggests, try a cable direct from a (different) laptop to the projector and check again.

[djskytv]

I found that the mirror where the bulb goes in gets distorted with heat over time especially when the bulb blows