Film-Tech Forum ARCHIVE: NEC 3240 Dim

This is topic NEC 3240 Dim in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Paul Stevens (Member # 4016) on 11-03-2012, 05:32 PM:

Can only get 4fl out of this projector with at 6K bulb. Bulb is optimized. Projector has produced much higher values of light output since install but has gradually dimmed. Any one have experience with light engines possibly being the cause?

Posted by Marco Giustini (Member # 4544) on 11-03-2012, 05:48 PM:

we need more data here. What is the screen size? Are you talking about 2D or 3D? How many hours does the lamp have? Did you check physically if the lamp has blackened (remember there are risks involved, DO NOT do it if you are not trained on how to handle a Xenon bulb). And finally how did you check the light on the screen?

That said, my limited experience with NEC says that the NCC software potentially shows an inaccurate value when aligning the lamp. I tried on a few machines and the "peak" value shown by the software does NOT coincide with the actual peak on the screen. It's mentioned on a NEC note too if memory serves. I suggest you do it by eye, the old fashioned way.

Posted by Steve Guttag (Member # 268) on 11-03-2012, 07:46 PM:

My experience coincides with Marcos regarding the light meter built into the projector.

Another key bit of information is what lamp you are using. If it is a cinema lamp and is being run hard...then it will decay relatively fast. Refocusing the lamp may need to be done as it ages and the lamp experiences burn-back.

DCinema lamps, aside from having a more optimized arc for the DCinema light path also have a much lower decay rate than traditional film-Cinema lamps.

It is highly unlikely that your light engine is the cause...other elements in the light path (mirrors, integrating rod...etc) could cause this but often with other artifacts showing as well.