Film-Tech Forum ARCHIVE: Drop contrast on Barco DP2k-12c

This is topic Drop contrast on Barco DP2k-12c in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Ivan Ivanov (Member # 9315) on 02-05-2016, 07:04 PM:

Please help with contrast problem on Barco-DP2K-12c.

3,5 Year old PJ located in controlled temperature and dust environment.
Last time (1,5 year ago) when measurement ON/OFF contrast by Klein-10A it was at about 1:2100. All Maintenance procedure done on time. Nothing change in projector expect lamps and software, same place, same room, same screen. Now contrast drop to 1:1200. Check and clean Light pipe, optics, port window, try different optics, check lamp, Install latest software, check PCF, actually check everything and finally nothing helps.

Posted by Mark Gulbrandsen (Member # 72) on 02-05-2016, 09:32 PM:

Seems like there was another post with a Barco and a similar issue not too long ago...

Posted by Carsten Kurz (Member # 5396) on 02-06-2016, 05:03 AM:

Yup, could be a similar thing:

http://www.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=16;t=002497#000005

- Carsten

Posted by Marco Giustini (Member # 4544) on 02-06-2016, 08:28 AM:

The prism exit area on Barco machines tend to get dusty. 12C should not be severely affected, particularly in a dust controlled environment, and dust on the prism exit and lens should not affect the black level and ON/OFF contrast - only the ANSI/interframe contrast.

My point is that nobody usually checks these values and what you found may be something common which has not been noticed around.

Another point is: how do you check contrast? Pointing the meter to the projector or to the screen? The auditorium will have a great impact on contrast if there is any residual light.

Let us know how it goes.

Posted by Ivan Ivanov (Member # 9315) on 02-06-2016, 10:16 AM:

For Check contrast use Black and White test pattern from Communicator.
Measurement by Klein-K10A from the centre of the screen.
Projector installed in post production grading room, with matte black wall, no EXIT sign, or lights on stairs. With projector switched OFF i measurement 0,00001 ftl on the screen.

Posted by Marco Giustini (Member # 4544) on 02-06-2016, 11:01 AM:

Ivan,

Try pointing the meter towards the projector - you may have a diffuser to add to provide you a reliable reading.

That way the measured levels will be much higher and the room and the tool sensitivity won't affect the readings so much.

I appreciate the room is very dark but contrast is greatly affected by the tiniest amount of light, even a little tea table in the wrong place can affect a reading - that said ON/OFF readings shouldn't be too affected.

Posted by Ivan Ivanov (Member # 9315) on 02-06-2016, 02:23 PM:

Marco,

My problem is:
Projector, room, screen, wall paint don't change between measurement.
I has contrast 1:2100 in this room with same colormeter, also with different one for exclude problem with colormeter.

Posted by Marco Giustini (Member # 4544) on 02-06-2016, 06:03 PM:

I was just trying to rule out elements. If you already know the room is ok, then open a ticket with Barco and request a new light engine.

Posted by Ivan Ivanov (Member # 9315) on 02-06-2016, 07:27 PM:

Thank You Marco for help.
I'm already send all information to Barco, but I was hoping that maybe i'm was missing something.