Video Display Issues - House of Worship

[Audioplus]

Having been in the high end A/V industry for 29 years, I get inquiries for trouble shooting from consumers and commercial applications. Recently, a local House of Worship contacted me, they have 2 projectors in worship area and 3 ea LED TV displays in center Hall. During worship service, they all start flickering, and have to turn the LED's and a projector off.
I started by looking at equipment, power protection, 2 each HDMI 1 x 4 splitter's (they have abandoned a Monoprice 1 x 4 with baluns). During the weekday I visited, no issues. After I left, the manager noticed the Monoprice was not on, he powered it up, and the displays flickered momentarily. Nothing was output or connected to the Monoprice, so first assumption that it's electrical issue. I informed them nothing is connected to the Monoprice. They are using shielded CAT6, no runs are longer than 100' max. I then inquired with electrician what is different during the day, microwave, coffee maker, etc. What about dimmer's and lighting. He discovered that bulbs or lighting may be issue, when the lighting attenuator's are all the way up or all the way down, no issue. Is there a chance that florescent, incandescent, or led lighting combined with the wrong dimmer switch can be creating interference through several separate AC circuits? Thus interfering with the HDMI video signals to the displays?
Anyone have an idea where to start, dimmer or the lights themselves? FYI, I did take into consideration ground loop issues, but believe the lighting, ballast or dimmers creating the problem.

 

[TLS Guy]

Having been in the high end A/V industry for 29 years, I get inquiries for trouble shooting from consumers and commercial applications. Recently, a local House of Worship contacted me, they have 2 projectors in worship area and 3 ea LED TV displays in center Hall. During worship service, they all start flickering, and have to turn the LED's and a projector off.
I started by looking at equipment, power protection, 2 each HDMI 1 x 4 splitter's (they have abandoned a Monoprice 1 x 4 with baluns). During the weekday I visited, no issues. After I left, the manager noticed the Monoprice was not on, he powered it up, and the displays flickered momentarily. Nothing was output or connected to the Monoprice, so first assumption that it's electrical issue. I informed them nothing is connected to the Monoprice. They are using shielded CAT6, no runs are longer than 100' max. I then inquired with electrician what is different during the day, microwave, coffee maker, etc. What about dimmer's and lighting. He discovered that bulbs or lighting may be issue, when the lighting attenuator's are all the way up or all the way down, no issue. Is there a chance that florescent, incandescent, or led lighting combined with the wrong dimmer switch can be creating interference through several separate AC circuits? Thus interfering with the HDMI video signals to the displays?
Anyone have an idea where to start, dimmer or the lights themselves?

First of all light dimmers make huge amounts of RF. The least is from the Lutron Maestros. Now fluorescent lights should not be dimmed. They also produce RF. LED bulbs produce huge amounts of RF. As far as dimming is concerned you need to make sure the bulbs are dimmable, a lot are not. Next you need to make sure the dimmers are specifically designed for LED bulbs.

If you do that you will minimize RF by air and wiring. However you will by no means eliminate it.

If a dimmer SCR crosses at the zero crossing there is no RF, but it is a lousy dimmer. The trick is to design as close as possible to the zero crossing compatible with reasonable dimming performance. I know the Lutron Maestro dimmers are designed to be as innocuous as possible round AV equipment as I worked closely with Lutron engineers to make this happen.

The other issue, is that there may be EDID conflicts between the screens. This is common with multiple screens connected via HDMI splitters. This problem can be really intractable.

 

[Audioplus]

Thanks for reply TLS Guy!
Other than a single initial trip to view their issue, it wasn't happening at 11:00am on a weekday. So, intermittent, or what's different on Sunday. They referred me to whom I believe is their electrician and initiated the above conversation. He determined when dimmer's were all on or all off, virtually no interference. I do realize that dimmers are made for specific applications, and that electrician's are not necessarily up to speed on low voltage issues. Being a House of Worship, I'm attempting to look at the most cost effective solution first. Also, various HDMI cables, v 1.3, v 1.4, v 2, etc can be the culprit when used in same system and not matched. Since this issue just presented itself, I'm guessing it's a bad dimmer?

 

[Audioplus]

TLS Guy, they are Lutron 600W, can they go bad in a few months? Or is there a way to check the performance?

 

[everettT]

TLS Guy, they are Lutron 600W, can they go bad in a few months? Or is there a way to check the performance?

Not so much the switches, but the fixtures. How is the wiring run? Separate or same conduit?

 

[TLS Guy]

TLS Guy, they are Lutron 600W, can they go bad in a few months? Or is there a way to check the performance?

600 watts is an enormous load for an SCR dimmer and would produce a lot of RF. Why is there so much power on the dimmer if you have LED bulbs?

If you need that much power you need to go to an Autotransformer dimmer.

 

[highfigh]

Having been in the high end A/V industry for 29 years, I get inquiries for trouble shooting from consumers and commercial applications. Recently, a local House of Worship contacted me, they have 2 projectors in worship area and 3 ea LED TV displays in center Hall. During worship service, they all start flickering, and have to turn the LED's and a projector off.
I started by looking at equipment, power protection, 2 each HDMI 1 x 4 splitter's (they have abandoned a Monoprice 1 x 4 with baluns). During the weekday I visited, no issues. After I left, the manager noticed the Monoprice was not on, he powered it up, and the displays flickered momentarily. Nothing was output or connected to the Monoprice, so first assumption that it's electrical issue. I informed them nothing is connected to the Monoprice. They are using shielded CAT6, no runs are longer than 100' max. I then inquired with electrician what is different during the day, microwave, coffee maker, etc. What about dimmer's and lighting. He discovered that bulbs or lighting may be issue, when the lighting attenuator's are all the way up or all the way down, no issue. Is there a chance that florescent, incandescent, or led lighting combined with the wrong dimmer switch can be creating interference through several separate AC circuits? Thus interfering with the HDMI video signals to the displays?
Anyone have an idea where to start, dimmer or the lights themselves? FYI, I did take into consideration ground loop issues, but believe the lighting, ballast or dimmers creating the problem.

Is the resolution of all TVs and projectors the same? If not, EDID is the cause of the problem.

 

[highfigh]

600 watts is an enormous load for an SCR dimmer and would produce a lot of RF. Why is there so much power on the dimmer if you have LED bulbs?

If you need that much power you need to go to an Autotransformer dimmer.

They're supposed to be de-rated when ganged in a junction box, too- sometimes, this is ignored and it causes problems with operation and premature failure.

 

[highfigh]

TLS Guy, they are Lutron 600W, can they go bad in a few months? Or is there a way to check the performance?

http://www.lutron.com/en-US/Education-Training/Pages/LCE/DimmingCFLsandLEDs.aspx

Dimmers for LED are very different from others.

 

[Audioplus]

Per the electrician, or manager '
Wiring for the light fixtures? Well, all the LED light sockets/fixtures are all on the same circuit in the Lobby electrical panel. I assume they are run up the wall in multiple conduits, but I’m not sure about that.
Is he saying the fixtures (light bulbs/lamps) are what is potentially bad?'

 

[Audioplus]

Per facility manager '

So I’m not at all familiar with de-rating, (other then what I just read) however I’m pretty sure we are not operating at a lower current capacity with those dimmers. From what I know we are at full strength…which is what you are suggesting is likely the problem.
So is it the heat that is present in the side by side configuration when ganging that wrecks the switch?