Underpowered DMX signal output on D512?

usb to dmx (2009 - 2019)

Underpowered DMX signal output on D512?

Postby SeekLighting » 14 May 2017, 20:23

Hi Support,

Came across an interesting little problem yesterday at a production tech run.

The venue I'm in has a very large lighting rig, and the space itself is very large so the distance of the cabling from the front to the back of the theatre is very long. When running my show file, intermittently the lights started going crazy by themselves without me touching them. This eventually led to me having no control over anything but the first 24 channels (which coincidentally were the first lights in the DMX chain)

We performed all the usual checks- checked all the cabling, adapters, terminators, USB ports and cables, etc. We swapped out the D512 for the venue's in-house Martin M1, and it had no issues whatsoever. The D512 was not faulty either as I had two D512s there on the day, one I purchased last year and one I purchased just a few days ago. Both had the same problem.

The solution: I plugged the D512 into the DMX IN of the Martin M1 and used it as kind of a DMX pass-through. The house tech said that my D512 is not outputting enough voltage to get the DMX signal all the way through the signal chain to the end. By going through the M1, I was using its much stronger DMX signal to boost it.

This is a pretty serious hardware issue that the D512 seems to have, in that the voltage it's outputting is pretty low compared to most other lighting consoles. Just wondering if you had any insight into why this particular problem is happening and any possible solution? I'd really not be keen on having to run through a second lighting desk in every big venue I go to! (some desks don't have a DMX IN!)
SeekLighting
 
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Re: Underpowered DMX signal output on D512?

Postby support » 15 May 2017, 08:12

The dmx outputs of this interface uses a standard dmx chip (SN75176), without any optical isolation. So there is an extra small protection with some resistors, which reduces effectively a bit the signal power. This is the effort to give to add some more small protection against ground loop, power surge, ...

With a "big" dmx fixtures installations, we strongly suggest you to afford a dmx isolator. This costs about 100 dollars/euros, you will have the full signal power for more than one dmx line, and your usb to dmx interface will be safe whatever happen in the dmx line.
FYI : https://www.enttec.com/eu/products/cont ... n/d-split/
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Re: Underpowered DMX signal output on D512?

Postby SeekLighting » 15 May 2017, 08:32

Hi support,

Thanks heaps for the advice and insight. I will definitely invest in an optically isolated splitter :)
SeekLighting
 
Posts: 364
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