# Help! Video flicker in QLAB



## TechGeek (Jul 20, 2014)

Hey guys

I'm running a show called Ocean City The Musical. The whole hour and a half show uses nothing but projection of videos for the whole show. My problem is that I'm getting a slight flicker in the image when projected but not on the computer. Our projector is a Barco DP2K-19b (link below). It runs movies through the Doremi Show vault and then the internal DVI for the live shows. 

My guess is that the refresh rate on the projector is too slow? 
I use a magenta system to send the video from the booth to the projector so it can't be the signal strength as it can send video through Cat5e up to 300'+

The problem is becoming a problem because it's doing this with our loops and still images for the show and when your looking at a screen for 3 minutes you start to see it.

We previously thought it was the XENON lamp which was partly it because it only had about 300 hours left of life. But once we replaced the lamp the problem is still there. 

Help!


http://www.barco.com/en/Products-So...ema-projector-for-screens-up-to-19m-62ft.aspx



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## ruinexplorer (Jul 21, 2014)

I haven't used Doremi products in at least seven years, so I don't have specific experience on this product. So, for my understanding, this problem developed recently with no change in your setup, correct? If this is so, I wonder what makes you think that this is a refresh rate. You can have a flicker in new Xenon lamps if they are not getting appropriate power to establish a stable arc. In the past, this was a common issue that would show up in a lamp after a few hundred hours. The projector manufacturers have greatly diminished the occurrence of this in the past few years. This is to say, it is still possible. It could be due to an internal power issue, or that you have too much of a voltage drop to your projector. 

When you removed the old bulb, did you inspect it? Was the envelop clouding? Could you see if the cathode was mushrooming or leaving uneven deposits on the anode? A better description can be found starting on page six here.

With one of the older model projectors that I used to maintain, we found that we needed to boost the incoming voltage to the higher end of the projector's tolerance to keep a stable arc for longer. This isn't something that I have noticed a need for with newer models, but might be something that you should approach with Barco tech support.

To determine if this is the projector (which is my guess based on the info provided), you should use a variety of the internal test patterns and see if you can find the flicker. You could also do this with some test slides coming from a laptop directly connected to the projector.


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## TechGeek (Jul 21, 2014)

I don't think we've changed anything in the setup except for using the internal DVI on the side of the projector and setting the lens to "Blueray flat" which is the setting we use to fit the screen with the videos we use for the show. 

Could there also be dust in the DVI input? it gets pretty dusty up there.

The reason I though refresh rate is because supposedly it doesn't have this slight flicker with movies. 

I'm thinking though that you can be right with the voltage drop. It might be that the movies move faster than the videos we play, which are a few loops. 
The section of the boardwalk we reside on has major power issues were the power is surging nonstop is this really hurting the lamp? However the projector is on a battery back up that according to the manager will last 3 hours but this projector backup battery charge is at like 25% because no one turns it off so it can charge. 

I am trying to figure out how to use the internal test patterns to see if it is this DVI input. 


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## ruinexplorer (Jul 21, 2014)

The flicker will probably still be there in a movie, but it will be very difficult to see. If the flicker were coming from the refresh, it would be more of a stutter. If it were the DVI input being dusty then you would also just be losing information (either a blanking or pixelization), not really a flicker. However, if it is really dusty, make sure to do regular preventive maintenance on the projector. Dust is your enemy!

I hope that your battery backup is also a power conditioner. If the power is as bad as I am imagining, this could definitely cause issues that can be long lasting. When I was working in ballrooms, where you can have very questionable power, I would often encounter issues with flicker. We would supply buck/boosters with the projectors to compensate. Voltage drop seems to be more common than spikes. If your boss is up to it, you might want to consider getting a power study done to make sure you are getting clean power to the projector and protect your investment.


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## TechGeek (Aug 6, 2014)

We fixed it. Had the company we hold a service contract with come out to fix one of the Doremi's for another projector in the theatre and had him look at the projector with the flicker. Here it was the was the last person who came out to service the projector didn't re-align the lamp so he did that and it's gone.


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## Amiers (Aug 6, 2014)

TechGeek said:


> We fixed it. Had the company we hold a service contract with come out to fix one of the Doremi's for another projector in the theatre and had him look at the projector with the flicker. Here it was the was the last person who came out to service the projector didn't re-align the lamp so he did that and it's gone.




It's always the small things isn't it


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## TechGeek (Aug 10, 2014)

Amiers said:


> It's always the small things isn't it



You bet!

I was so annoyed when I found out that it was the lamp alignment.


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