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Element not talking to sensor rack sort of

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goman1315 posted on 07-11-2012 10:46 AM



We are working in a high school auditorium trying to help the school get their systems cleaned up. The have to installed sensor racks in a remote location off stage left. They used to have a large express console that they recently replaced with an element. Ever since installing the element the only way they can get control to pass via DMX to the racks unless it passes through some other lighting fixture along the way. So for instance right now dmx comes out of the element into and through a chauvet color palet (that is not being used, or even patched, just powered on in the booth) and then passes along into the installed control line back to the dimmer room. Everything works fine. Run direct from the console to the dimmer room and nothing works or responds. This was not a problem nor was there ever any issues with the old express controlling the dimmers. Any ideas or things to look at? We already tried experimenting with turning off all the extra control proticals and slowing down the dmx speed to no change.


Thanks for your help!!

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Top 25 Contributor
493 Posts

Hi there!

In chatting with a few people here, it sounds like the wiring in the wall may have Data- and Common swapped.  Likely, the Chauvet fixture has a small bit of resistance between the two, or Data- and Common are tied together.  You should be able to take a look at the wall plate, and try reversing these connections and see if it helps.  For more information on the pinout, please see this wiki article: http://www.etcconnect.com/Community/wikis/products/dmx.aspx

Otherwise, if this is a Sensor Classic rack, the termination board may be going bad -- if you give your local ETC Tech Services a call, we'd be happy to talk you through looking at that.


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Hans Hinrichsen

ETC Technical Support Specialist

Top 500 Contributor
15 Posts
Suggested by Richard


Personally I'd take a good long look at the installed wiring, when DMX starts doing weird things more often than not it's down to a problem with the cables. Check the cables are suitable for DMX/RS-485 and not just some bit of old mic cable. Also try re-soldering the connectors, even if they are wired correctly, a dry joint can cause all sorts of strange things to happen.




Top 75 Contributor
153 Posts

Assuming you tried different DMX cables, have you tried the other DMX output on the board?  It could be a bad DMX output driver that the fixture is buffering/compensating for.

Also, if you power down the rack and unplug DMX from the board, you should meter around 120 ohms between pins 2 & 3, and open between pins 1&2, and 1&3 with the CEM installed, and open between all pins with the CEM removed.

That said, I'm not sure how RDM and any source termination may play into this.

Bruce Klotz Theatrix, Inc

Top 10 Contributor
1,425 Posts

This is almost certainly a bad cable, my guess is that Hans is right and there's a swap or a short on Data-/Common.

- However, it's not necessarily a bad cable between console and the first fixture, it could be any segment of wire between the console and the dimmers (and beyond)

Test all your patch leads thoroughly, then test the installed cable. Pay particular attention to all the connectors.

Keep on trying till you run out of cake.

ETC Field Service, London

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