Film-Tech Forum ARCHIVE: NEC 900C rainbow

This is topic NEC 900C rainbow in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Brian DeCiancio (Member # 1422) on 04-28-2016, 04:59 PM:

I had strange arced "rainbows" show up one day on a 900C. Three of them were visible on the left 1/3 of the screen

Oddly, the fix was as simple as removing and reseating the lens.

Just wanted to share.

(I can't get the image to upload).

Posted by Rachael Barbash (Member # 5158) on 05-20-2016, 07:27 PM:

On one of our NC1200c we've been having kind of almost a reddish reflection on screen whenever the lamp is on. I wonder if it's a similar problem. Did you remove the lens yourself or have an outside tech do it?
Thanks for posting!

Posted by Mark Gulbrandsen (Member # 72) on 05-21-2016, 09:54 AM:

Since the NC-900 lens is bayonet mount I am surprised that just removing and re-seating it was the fix. Very odd....

Rachael, On yours try closing the douser and see if the red smear goes away with it closed. NEC's generally do have a bit of light leakage in idle mode with the lamp lit, but nothing terrible.

Mark

Posted by Marco Giustini (Member # 4544) on 05-21-2016, 05:59 PM:

any chance we are talking about moiré effect? Reinstalling the lens maybe drifted the focus a little.

Cannot find a picture that shows it.

Can you try re-focussing the projector using a test pattern? If I'm right the 'rainbow' will come back. Nothing you can do for it besides defocussing the picture - or replacing the screen

Posted by Mark Gulbrandsen (Member # 72) on 05-22-2016, 05:39 PM:

Or just re-level it just slightly. You want it in focus. Not out of focus.

Mark

Posted by Brian DeCiancio (Member # 1422) on 05-24-2016, 12:31 PM:

I re-seated the lens myself. It wasn't difficult.