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[Kristian Johnsen]

Hi all.

I have been a regular on the audio side of this site for a while but this is my first post on the lighting side, so I'll introduce myself just so you regulars know what "shelf to put me on":

I run a small sound and light company in the city I live in and have the following lighting gear in rental inventory:

16 PAR 64s on dimmer booms.
8 PAR 56 floor cans.
8 fresnel front lights.
4 four-channel Eurolite compact dimmers.
8 Martin Magnum SCX 500 scanners.
16 Geni Spyro disco-style DMX fixtures.
8 1500w DMX strobes.
2 smoke machines (Martin Magnum 1500 and 2000 both w/ DMX module)
1 Martin Magnum Hazer.

My small "big" console is a 12 channel MA Light Commander.
I also have a 12 channel Zero 88 desk without programming options, a 12 channel LitePuter desk, an 8 channel Eurolite compact controller, an Eurolite Scan Commander and a Martin 2510 loaded with programs for the scanners.

I also have all manner of stands, cables, 3-phase distros, etc - some of it shared with my audio gear.

Anyway, that's me - here's my problem:

Most all the gear performs as expected and in general I have very few problems with it, however I have these two puzzling issues:


1).  The LitePuter desk/Martin Magnum 1500 smoke machine refuse to cooperate.  The Martin indicates DMX received, but will not blow smoke when the correct channel on the desk is activated.  Just unplugging the cable going from the LitePuter to another desk makes the smoke machine work.  The LitePuter desk has no problem controlling other DMX gear.  I know a lot of people will ask me to use proper DMX cables:  I mostly do, although the DMX signal does pass through the audio snake in this setup.  However - no problems on any other gear in this setup, and the symptom is not irradic behaviour; just lack of function.

2).  The combination of the Eurolite compact dimmers and the Eurolite 8 channel controller gives me an interesting symptom where all channels randomly "blink" really quickly with irregular intervals.  It's so quick, a lot of people don't even notice, but the lights do in fact go to black for a split second every now and then.  All dimmer channels are affected.  Simply unplugging the DMX and plugging it into another desk solves the problem.  I have never experienced the Eurolite desk doing this with any other DMX gear I have controlled with it.  Again, cabling:  Symptom is present with DMX cable going directly from desk to dimmer.  I have tried several cables that all measure fine.


Hope someone can shed some light on these annoying issues - thanks in advance !

[Tony "T" Tissot]

Baffling combinations.

Do you use a terminator at the end of the DMX chain? (120 Ohm resistor across pin 2 and 3.)

Are all devices (assuming you have the option) set to pin 2+ ?

[Kristian Johnsen]

Tony "T" Tissot wrote on Mon, 20 July 2009 19:59

Do you use a terminator at the end of the DMX chain? (120 Ohm resistor across pin 2 and 3.)

DOH!

I'm an idiot!  I certainly will try that!  Some devices I have even have a termination switch built-in, but I'm very sloppy when it comes to actually using them

[Kristian Johnsen]

Hi again.

Tried termination on scenario 2). today, but no difference.

On the positive pin issue, I assume all units are or they would not work correctly together in the first place?  I have a Martin 2510 controller that needs a polarity reversal cable to work with the scanners.  I tried not using it once and everythig just went bananas, so I always gathered flipping polarity would not work at all?

Any other suggestions?