Film-Tech Forum ARCHIVE: Screen going black intermittently

This is topic Screen going black intermittently in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Nate Anderson (Member # 2711) on 02-03-2011, 12:56 PM:

2 months ago we installed a Christie Series 2 projector with a Dolby DSS 200 processor on one of our screens. It has run fine until we started playing "Black Swan" a couple of weeks ago.

Twice in the past 2 weeks, while the feature is playing the screen will go black for a split second and then comes back on. I checked the bulb and that is not the problem. So I figured the content had to be corrupted. I deleted the content and uploaded a fresh copy and that seemed to solve the issue.

However it did the exact thing again the other so I repeated the delete and reload content procedure, but it seems like I'm treating the symptoms and not the disease. Any ideas?

Posted by Jeremy Weigel (Member # 4208) on 02-03-2011, 01:53 PM:

Have you tried rebooting the server?

Posted by Jonathan Althaus (Member # 5042) on 02-03-2011, 02:29 PM:

Our Barco series 1 has this issue and we traced it back to loose coax from the server to the projector.

Posted by Steve Guttag (Member # 268) on 02-03-2011, 03:20 PM:

Note...on a series 2, you also have an enigma board in there and one of the things it CAN do is blank the screen. Certainly cables are a place to look, including the Ethernet cables and all of the go-betweens.

Have you tried looking at the logs to see if there was anything noted? If you think it is an HDSDI cable issue, there should be errors growing on that log.

-Steve

Posted by John Gavin (Member # 5949) on 02-09-2011, 02:20 AM:

Check for SMPTE link errors particularly on the B-Link
( usually the projector has a page or tab in the diagnostics
section or tab ).

Alternatively, you could try longer coax cables ( 3m or longer )
SMPTE link errors tend to cause black-outs in 2D content and
green-outs in 3D content and be random.

Posted by Steve Guttag (Member # 268) on 02-09-2011, 06:29 AM:

To the best of my knowledge, the cable length related issues were a phenomenon of the Series 1 projectors. Something to do with proximity of the traces causing chatter if the signal strength was too large on the 292-B input.

I have not heard about any issue on series 2 projectors.

Again...check the 292 error logs...they will tell if it is related to the cables.

-Steve

Posted by Scott Norwood (Member # 30) on 02-09-2011, 11:39 AM:

Stupid semi-on-topic question: what is the failure mode in a D-cinema system if one of the two HD-SDI links is lost? Does the picture go away entirely, or does it come out in black and white or with incorrect colors? Or does something else happen?

Posted by Steve Guttag (Member # 268) on 02-09-2011, 12:06 PM:

It all depends...

In 2D mode...you will have either no picture or funky color picture. The "A" port is carrying 4:2:2 information but port "B" is carying 0:2:2.

One BIG problem with DCinema is the complete lack of redundancy in everything. About all that seem to have some form of back up are power supplies and even that isn't anywhere near universal.

If any part of the projector breaks (except maybe a lamp power supply if it is a multi-module supply like Barco) you are down. If anything fails in the server/player, you are down. Even the sound system is no longer backed up. With film, there was always an redundant path for the audio to eek through, in some form. Even old Mono sound systems had spare amps or the exciter supply had an AC "bypass" mode. Not so with digital and DCinema...with the exception of maybe USL's JSD100, there is simply no back up.

And again, unlike film cinema were the equipment is mature and spare parts can be had for most any of the projectors in typically hours, not days, DCinema is still evolving so fast few have any spare parts anywhere...you are waiting for something to be "reded in" I had a projector go down on a Friday and I've had a media block go down on a Friday now. You feel so helpless because you can't do anything without the replacement parts.

-Steve