Weird glitch

[Amiers]

So Today durning the show the lights decided to act on their own and started lighting up at random. It also affected my movers and my led walls. It only stopped after I powered down my movers.

My question is why would my Expression 3 stop outputting all together of only 1 universe decided to go nuts and stop working?

I have yet to be able to recreate what happen. I am crossing my fingers that it doesn't happen again but I would love to know if anyone has any ideas.

The movers are on their own power , and terminated at the end of the chain with good cable.

The dimmers are a mix of 6 channel elation and beringer. Also with good cables and terminated at the end.

 

[SteveB]

The Expression series consoles were notorious for sending a random DMX stream at console power off. The racks/devices then hold last look, now seeing no DMX. The typical solution when encountered was to drop all levels, then pull the DMX cable(s) then power down.

 

[Amiers]

Yeah I deal with that all The time but never in the middle of a show. The board had been on for atleast a few hours before show as well. It gets powered down everyday.

Do you think it was more of a board issue instead of a mover issue?

 

[derekleffew]

My question is why would my Expression 3 stop outputting all together of IF only 1 universe decided to go nuts and stop working?

Recapping the scenario to make sure I understand: In the middle of the show, one universe goes wonky, sending erroneous data to dimmers, movers, and LED walls, AND the other (1 or 2) universes stop outputting completely? Powering down the movers fixes everything? Now the problem cannot be reproduced?

As a precautionary measure, I'd have some Exp3 DMX driver chips*, as well as a new power supply, on hand just in case. (Provided a duplicate console is out of the question.)

* http://www.controlbooth.com/threads/express-faceplate-problems.20280/#post-182930
http://www.controlbooth.com/threads/hit-by-lightning.14833/#post-142857

 

[Amiers]

Recapping the scenario to make sure I understand: In the middle of the show, one universe goes wonky, sending erroneous data to dimmers, movers, and LED walls, AND the other (1 or 2) universes stop outputting completely? Powering down the movers fixes everything? Now the problem cannot be reproduced?

As a precautionary measure, I'd have some Exp3 DMX driver chips*, as well as a new power supply, on hand just in case. (Provided a duplicate console is out of the question.)

* http://www.controlbooth.com/threads/express-faceplate-problems.20280/#post-182930
http://www.controlbooth.com/threads/hit-by-lightning.14833/#post-142857

Yes you are correct. I was switching between acts and my LED walls flashed during a black out so I went to clear the A/B Fader and then everything started to freak out when the computer fired the next cue about 20 to 30 secs after the cue it cleared itself back up as I was trying to figure out what happen. I went through 2 more cues before it happened again. I then cut power to the movers and ran the rest of the show fine. After the show we turned the movers back on and stress tested the system and everything ran fine.

 

[Bubby4j]

Could it be using regular mic cable instead of DMX cable? Maybe not using a terminator? Or maybe a bad connector on one of the fixtures/cables?

I've had a connector go bad on a fixture which caused weird flickers, especially when someone was walking on the stage which caused vibration to the fixture.

 

[Amiers]

The cables for the movers were all bought new and installed by me and haven't moved since. I will say that we do have vibration problems though. Being that the build is converted from an old pole barn and the way the horses come in are through some big doors that are operated with 80 psi actuators. I will have a look at the movers tomorrow and see if the connectors are loose.

 

[FMEng]

In a dirty environment like that, I would go through all the XLR connectors and wash them with DeoxIT D5. It sure wouldn't hurt anyway. All it takes is a little invisible oxidation on connector contact for things to go awry.

 

[STEVETERRY]

In a dirty environment like that, I would go through all the XLR connectors and wash them with DeoxIT D5. It sure wouldn't hurt anyway. All it takes is a little invisible oxidation on connector contact for things to go awry.

For sure, that's the right product for the job. However, Murphy says it has a low probability of fixing the problem.

ST

 

[Amiers]

Yeah I agree Steve. It's the first time it has ever happened. It wasn't a show stopper but the troubleshooter in me makes me want to know. I almost want it to happen again so I can film it or figure out the root of the problem but with most things it only happens when you aren't trying to get it to happen.

 

[BillConnerFASTC]

Low probability but recently opened a project and the whole batch of patch cords - the very best and most ruggedized from a well known company in our industry - was not assembled per spec. I don't know the detail but some screw in the shell was not tight on the whole batch and had multiple failures. Don't assume new is without fault.

I've learned this a number of times - most recently canoeing. Only paddle to ever break was a brand new one - not fifty yards out. The beat up old spare was fine for the week.

 

[Mac Hosehead]

Since no one has mentioned this yet, I will chime in. After reading the account in the first post about one DMX line affecting others from the same console, the first thing that came to my mind was that voltage is coming back down the DMX line. Be aware a DMX output on an Expression console with monitors is a path to earth ground. If another connection to earth ground is made on a DMX line away from the console then there is the possibility of a ground loop. Ground loop problems can be insidious in that everything seems fine at one time and then maybe nothing works at an other time. There is a popular fog machine that is no longer made that had a connection to earth ground in its DMX interface and I would see problems related to that from time to time. There is also the chance that one of the moving lights was sending a voltage down the DMX line. IMO, this is less likely but in theatre anything can happen and does.

Of course, this is just one possibility. A DMX opto-isolator in line would prevent something like this from happening. Some fancier consoles have isolation built into their DMX outputs.

-MH

 

[DavidNorth]

Be aware a DMX output on an Expression console with monitors is a path to earth ground.
Of course, this is just one possibility. A DMX opto-isolator in line would prevent something like this from happening. Some fancier consoles have isolation built into their DMX outputs.

-MH

Well, the DMX in Expression 3s is partially optically isolated, but not on the data common pin, so we have to be cautious here. Common is not tied to ground in the console, which most manufacturers do on their output. But yes, it's correct that it can be tied on receiving devices as well which makes for quite a mess.

An opto-splitter might help, but depends on where the ground loop is, if there is one, or only one, but yes it can help. However, if it starts to occur again with the setup as is, disconnect the monitor and see if the problem goes away. That would answer part of the question.

David

 

[Amiers]

So I do have and opto splitter that the LED walls and the movers run through. It lives in the middle of the arena. Everything fingers to it and one line comes from the arena for four movers and 7 3ch dmx led decoders.