Control/Dimming DMX refresh flash on cheaper LED's

J

James Mierkey

Member
We recently moved to controlling our lights through QLab using an entec ODE interface. As soon as we did that, we started getting a flash on all of our LED fixtures every 120 seconds. We were previously using an ETC console. I have played with the refresh rate on the entec and can slow it down or speed it up but it doesn't go away completely. I have double checked every single DMX cable for issues. As soon as I switch from the entec back to the ETC console, the flashing stops. I realize that this is an unfortunate reality when using less expensive LED fixtures (prosumer/DJ level stuff). We're a small community theatre and we get a lot of bang out of those cheaper fixtures. Is there anything I can put inline on the DMX chain to reduce or remove this flash? A splitter/isolator? Anything?

I appreciate any help you can give.
 
you sharing the VLs on the same DMX line?
 
Sometimes splitting things up helps with different equipment. This is tedious but try running one fixture by itself if it doesn’t flash then 2 and so on so forth til something flashes. Hopefully you can get up to 25 without the VLs
 
James Mierkey said:
Yes. We have one DMX chain with about 25 fixtures on it (post ETC 24x2.4 dimmer pack) including the two VL's i mentioned in other post.
Click to expand...
@James Mierkey Two queries and one thought: Are you running XLR3's or XLR5's?
By any chance is contact 1 of your DMX grounded via your console when your console's driving your DMX cables directly AND un-grounded when your Entec interface is driving your DMX line?? I'm wondering if static electricity is building up on the shield of your DMX cables and your shield is grounded when connected directly to your console via the third pin of its power cable but your DMX cables' shields are NOT grounded when being driven by your Entec interface.
Just a thought from north of Donald's walls.
@Amiers Wha'dya think???
Toodleoo!
Ron Hebbard
 
Last edited:
Another possibility. Would have to know the specifics of the the entec box to know for sure. Some use power some draw striaght from a usb cable.
 
Amiers said:
Another possibility. Would have to know the specifics of the the entec box to know for sure. Some use power some draw striaght from a usb cable.
Click to expand...
Entec box is plugged in to AC (wall wart). We are DMX3 right now and are having to run 5to3 adapters at the VL's and dimmer pack. The grounding issue is intriguing. I would have to check the specs on the entec box to know for sure.

https://www.enttec.com/product/controls/dmx-ethernet-lighting-control/ethernet-dmx-interface/
 
James Mierkey said:
Entec box is plugged in to AC (wall wart). We are DMX3 right now and are having to run 5to3 adapters at the VL's and dimmer pack. The grounding issue is intriguing. I would have to check the specs on the entec box to know for sure.

https://www.enttec.com/product/controls/dmx-ethernet-lighting-control/ethernet-dmx-interface/
Click to expand...
@James Mierkey Is your Entec powered via a three pin or two pin wall wart? (I'm asking if your wall wart's input power is via a ground pin or not?? I suspect this could make a difference if your DMX cables' shields are un-grounded when your Entec is your source. @Amiers Thoughts???
Toodleoo!
Ron Hebbard
 
James Mierkey said:
...Is there anything I can put inline on the DMX chain to reduce or remove this flash? A splitter/isolator? Anything?
Click to expand...
proxy.php

http://www.dfd.com/dmxdecel.html is a good candidate.
The DMX Decelerator is a DMX512 isolator and re-timing device. It can receive any signal within the DMX512 specification and it can accept some signals outside of the specification. It produces a DMX output signal with “relaxed” timing characteristics which are required by some DMX receiving devices.
Click to expand...
 
James Mierkey said:
The Entec box does not use a grounded plug but the ETC console does (standard IEC cable). This may be the issue.
Click to expand...
@James Mierkey As a quick 'n dirty test, go to any convenient DMX XLR post the output or your Entec and connect pin #1 to a known good ground; a metallic cold water pipe, the outside of a grounded piece of electrical conduit, a clean spot on a structural steel beam, the ground contact of a properly installed duplex receptacle; basically any known good ground.
If you've a trustworthy meter handy, verify your ground point is really ground and not bridged to neutral in a hastily installed duplex receptacle.
Once you're absolutely certain you're looking at a good ground, then connect it temporarily to your DMX cables' shield and see if you win.
If you win, solder a wire to pin one of an XLR, ground your wire and plug in your ground.
This'll be far more reliable than trying to tape a piece of grounded wire to an XLR.
Best wishes from north of Donald's walls. @Amiers Any further thoughts??
Toodleoo!
Ron Hebbard
 
RonHebbard said:
@James Mierkey As a quick 'n dirty test, go to any convenient DMX XLR post the output or your Entec and connect pin #1 to a known good ground; a metallic cold water pipe, the outside of a grounded piece of electrical conduit, a clean spot on a structural steel beam, the ground contact of a properly installed duplex receptacle; basically any known good ground.
If you've a trustworthy meter handy, verify your ground point is really ground and not bridged to neutral in a hastily installed duplex receptacle.
Once you're absolutely certain you're looking at a good ground, then connect it temporarily to your DMX cables' shield and see if you win.
If you win, solder a wire to pin one of an XLR, ground your wire and plug in your ground.
This'll be far more reliable than trying to tape a piece of grounded wire to an XLR.
Best wishes from north of Donald's walls. @Amiers Any further thoughts??
Toodleoo!
Ron Hebbard
Click to expand...
I love this idea. I'm feeling confident about this solution. We have had ground issues in our building, to the extent that I have installed an isolated proper ground rod and run all of our audio equipment to this common ground to close all the ground loops we were experiencing. I appreciate all of your input. If the ground issue doesn't work, I may have to go with the Fleenor box option to try to deal with refresh timing, etc.
 
I would see if you get the flickering with just 1 fixture before you attempt to ground the box or get a decelerator
 
I would called entec before modifying anything and of course call DFD about his decelerator before buying it. @jfleenor can help you with this and I don’t think we have an entec rep on here so you might have to goto their website.
 
James Mierkey said:
I love this idea. I'm feeling confident about this solution. We have had ground issues in our building, to the extent that I have installed an isolated proper ground rod and run all of our audio equipment to this common ground to close all the ground loops we were experiencing. I appreciate all of your input. If the ground issue doesn't work, I may have to go with the Fleenor box option to try to deal with refresh timing, etc.
Click to expand...
@James Mierkey Your mention of a dedicated ground rod for your sound equipment opens a fresh can of worms. Decades ago, separate isolated ground rods for audio became a fad. When serious ground faults in audio gear began killing people rather than blowing fuses or breakers, your NEC folks got interested and I suspect you'll find you can add as many new ground rods as you like BUT I suspect you'll find ALL grounds in a facility need to be bonded to the ONE AND ONLY official ground point in a given building, usually this is a solid copper grounding bus routed around the perimeter of the room where your power service enters your building.
I've done installations north and south of Donald's walls and this has ALWAYS been the case. @Amiers , @TimMc and @Jay Ashworth Thoughts???
EDIT: @MNicolai Mike, since you're awake, would you mind commenting on isolated ground rounds in the land of your NEC?
 
Last edited:
Did you happen to download and try any of the other software lighting control packages? There are several listed on the Enttec web site. I'm sure QLab would be considered the best Mac based solution, but a free trial of something else might be insightful. And then there's the Windows world...
 
RonHebbard said:
@James Mierkey Two queries and one thought: Are you running XLR3's or XLR5's?
By any chance is contact 1 of your DMX grounded via your console when your console's driving your DMX cables directly AND un-grounded when your Entec interface is driving your DMX line?? I'm wondering if static electricity is building up on the shield of your DMX cables and your shield is grounded when connected directly to your console via the third pin of its power cable but your DMX cables' shields are NOT grounded when being driven by your Entec interface.
Just a thought from north of Donald's walls.
@Amiers Wha'dya think???
Toodleoo!
Ron Hebbard
Click to expand...
Maybe I'm getting the term "ground" confused here, but in a DMX system pin 1 of the XLR should never be connected to the shell of the connector per Bennette's "Recommended Practice for DMX512". Quote from page 8: "The shield must not be connected to, or be in contact with, the shell or body of either the male or female connectors because chassis mounted connectors are generally connected to mains ground and this could cause problems with ground loop currents." (Itallics are his). In fact, some imported 3-pin cables do have pin 1 tied to the shell and this will likely cause problems in a DMX system.
 
You must log in or register to reply here.

Similar threads

R
New Ion xe no DMX on boot
Replies
14
Views
824
derekleffew
derekleffew
B
Open 4/12, dmx decoder/LED tape works from board not stage.
Replies
7
Views
574
almorton
A
S
Altman LED Fixtures intermittent failure
Replies
9
Views
532
TimMc
TimMc
J
Design Bad theater infrastructure help
Replies
16
Views
2K
Jay Ashworth
Jay Ashworth
M
DMX network for new led lights and movers
Replies
11
Views
2K
StradivariusBone
StradivariusBone

Users who are viewing this thread

Total: 1 (members: 0, guests: 1)
Back