I’m reaching my wits end.

I am in the midst of doing a big install in a new boardroom.  I have installed an Optoma TX 1080 on an Omnimount 3N1PJT onto a 120 inch Grandview inceiling motorized screen.  Once installed I noticed a significant shake in the image.  On inspection I realized the t-bar ceiling grid was shaking due to the air conditioner mounted on the roof above.  It shakes so bad you can feel it in the floor, walls, everywhere!  It physically shakes the screen itself!

I removed the projector, which was mounted to a drop ceiling insert, and installed it instead to industrial grade strut run between 2 joists.  The vibration continued. 

I ordered a Chief CMA-347 anti vibration kit and installed it, figuring this would cure the problem.  (not a cheap part)  It didn’t.

I am at a loss for what to do next.  I’ve suggested that the company get there a/c unit serviced which they are unwilling to do.  They feel it is not their responsibility. 

Does anyone have any suggestions?  Has anyone encountered this problem before?

Thanks for your help!

I have dealt with this same problem on a few occassions. Trying to eliminate the problem at the projector is not the solution and you will chase-your-tail spending lots of time and money trying to correct a problem caused by others. Your customer will be upset with you and blame you for the problem the longer you continue trying to “fix” the problem. The only solution is to have the HVAC system vibration controlled. First, have a HVAC technician check the blower fan (usually a squirrel cage type of fan) for excessive dirt on the blades as this will cause unbalance. Next have him check that its mounting rubber bumpers are in place and in good condition (they are like motor mounts in a car) - note, many HVAC don’t re-install them when they change out a fan as they are lazy and/or they don’t have them on their truck. The most important thing you can suggest is installing the proper Mason Springs to decouple the HVAC unit from the building structure.

http://www.mason-ind.com/masonind/home/index.cfm

While this is not your problem, you have made it yours by trying to fix it, when you can’t as you don’t have the experience, tools, products or the properly contractor license. It is best to stop working on it and get your customer to realize this is not something you need to be involved with. I hope your contract is written allowing you to get out of this problem while still getting paid for your services and products.

dmenagh - 10 August 2010 11:04 AM

I have dealt with this same problem on a few occassions. Trying to eliminate the problem at the projector is not the solution and you will chase-your-tail spending lots of time and money trying to correct a problem caused by others. Your customer will be upset with you and blame you for the problem the longer you continue trying to “fix” the problem. The only solution is to have the HVAC system vibration controlled. First, have a HVAC technician check the blower fan (usually a squirrel cage type of fan) for excessive dirt on the blades as this will cause unbalance. Next have him check that its mounting rubber bumpers are in place and in good condition (they are like motor mounts in a car) - note, many HVAC don’t re-install them when they change out a fan as they are lazy and/or they don’t have them on their truck. The most important thing you can suggest is installing the proper Mason Springs to decouple the HVAC unit from the building structure.

http://www.mason-ind.com/masonind/home/index.cfm

While this is not your problem, you have made it yours by trying to fix it, when you can’t as you don’t have the experience, tools, products or the properly contractor license. It is best to stop working on it and get your customer to realize this is not something you need to be involved with. I hope your contract is written allowing you to get out of this problem while still getting paid for your services and products.

Thanks for the input!  As it turns out, your advice was exactly the approach I took.  The company was not pleased, but got their HVAC company in to check the units.  The bearings were indeed shot and the fans were in need of balancing.  Upon this service being performed, the shake is less, but still there.  They called in another installation company threatening we would lose the job.  The replacement installers confirmed my diagnosis and suggested I had done everything in my power to fix the problem and that the roof would need to be restructured in order to fix the problem entirely. 

My client has returned and although not overly pleased about the shake, now realizes it is not something I could fix.  They have accepted it and we are moving on.

BRAVO DMENAGH!!!

As long as the projector held still while the HVAC was off, it’s not your problem. However, you have learned a valuable lesson…  Once you take a screw driver to someone else’s work, in the client’s eyes, you’re responsible.

I was suprised to see this thread.  I had the exact same problem a year ago and was unable to resolve it.  The vibration was more problematic on static images such as spreadsheets and powerpoints than motion video.  Since it was a conference room, this was an issue.  Thanks for the advice.  I will go back to client and have them look into these suggestions.  Great Post!

Whats the best way to stop this in a residential structure.  When somebody walks above the theater home, the floors move, thus causing the projector to bounce.  Any help for that?

First off, it’s important to know if the problem exists before you begin if there is indeed a floor/room above where the projector is to be mounted.

It sounds old fashioned, (but then again I’m no spring chicken), but the easiest and cheapest way is to take a half a glass of water attached to a cord or string, and affix the other end of the string to the ceiling, (like a plum-bob). Then have someone go upstairs and jump on the floor while you watch the glass of water. If you see the water moving in the glass, you have a problem.

The resolves I’ve seen are either to have a carpenter come in and reinforce the ceiling, or use a series rubber washers to act as a half-assed shock absorber around the threaded screws. It all depends how sensitive or extreme the problem is.

I’m also sure people will be giving me crap for the, “glass of water,” trick, but not everyone has or can afford the proper laser alignment tools.

Best of luck. BTW: The glass may also be half filled with an adult beverage of choice so no one notices, (or longer cares), about any movement.

Spreadsheets were the major concern in my situation as well.  I guess the owner of the company suffers from “motion sickness” and couldn’t handle it. 

Conundrum - 18 August 2010 05:40 PM

I was suprised to see this thread.  I had the exact same problem a year ago and was unable to resolve it.  The vibration was more problematic on static images such as spreadsheets and powerpoints than motion video.  Since it was a conference room, this was an issue.  Thanks for the advice.  I will go back to client and have them look into these suggestions.  Great Post!

edisonce - 19 August 2010 05:33 AM

Whats the best way to stop this in a residential structure.  When somebody walks above the theater home, the floors move, thus causing the projector to bounce.  Any help for that?

Items such as the Chief CMA-347 anti vibration kit are geared towards the occasional jolt from subwoofers, walking from above, big trucks rolling by, but they are a very large unit and don’t fit into most residential applications very well.  I found a few other kits in my searches but I just didn’t have any faith that they would have an adequate end result for the amount of money they cost. 

Talk to your customer, be up front about it and see how far they are willing to go to cure this problem.  After all, anything can be done with enough financial backing, right?

If your A/C is causing your building to shake that much you should have the a/c looked at. This is not normal for a roof a/c. Probably an out of balance blower wheel on unit.  I am an HVAC service tech.