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Time To Terminate?


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Hi, :blink:


I'm new to the forum. I'm hoping I can pick a few brains while im here!




Picture this, if you can !!


Set Up as follows;


A Zero 88 Leapfrog Desk > 2:1 DMX Merger (another input elsewhere) > 2 off 1:8 DMX Output splitters (linked via DMX THRU) > 12 independent outputs on grid (currently feeding 2 moving heads & 4 Led Parcans) & 2 off 24way Chilli's



Chillis addressed @ 1 >48


Heads addressed @ 50 onwards (29ch Mode)


LED Cans addressed @ 120 onwards (3Ch Mode)



All Cables Checked for polarity & continuity


All ''intelligent'' fixtures are new and presumably factory checked!


DMX Patching Checked at both ends


Desk checked for a 'generate random DMX fault' button (Not there!)



Chillis = Operate/Respond as expected - Good!


Heads = Operate/ Respond as expected- Woohoo!!


LED Cans = Operate/ Respond as expected.......When The output values for the chillis are set to 0 or <10% on the desk! - Oh poo!



When the output values of the chillis are raised, the Led Pars (oddly only 3 of the 4) begin to strobe continuously - but still offer full control of their attributes.


Time to invest in some terminators? Have I got a gremlin in the works? Or am I barking completely up the wrong tree?




Thanks for reading!



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Well, there's no harm in adding terminators especially as they are so cheap. But I would say this is not the symptoms I would expect. Instead I would suggest this is either an addressing error on the LED's, one or more faulty units or incompatibility between fixtures.


Use a process of elimination - ie. connect LED's direct to console avoiding all the distribution. If this works then start adding bits in one at a time until you find the guilty party.

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Termination is certainly something worth looking at, yes. It may not necessarily sort your problem out, but it's something quick, easy and relatively cheap to do, needing only a few quid, a nearby branch of Maplin and five minutes with a soldering iron!


Once you've done that, if things are still misbehaving, then you can delve into more complicated fault finding.

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This feels like the LED units are seeing the lower channels dimmer slots as either the DMX break or DMX start slot.


Are you sure the polarity to them is correct? I assume they have 3-pin XLRs on them? I may be teaching you to suck eggs here but remember that the pins on a 5-pin XLR run 1-2-3-4-5 but on a 3-pin they run 1-3-2.

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This is truly odd; it sounds like the LED pars are not in three channel mode, as many of these things have modes using more than three channels that offer effect such as strobing, but then the question becomes how the heck is it receiving channels out of its configured range when it is responding to the correct range?


Next clue is that it is three of the four cans; is the one that is OK the unit with the highest starting address?


This isn't a termination problem; your setup whilst not simple is very straightforward and has the distinct advantage over a single long cable that each DMX bus has very few devices on it.


So I'm going for double fault: parcans not in three channel mode, and your desk is not outputting what you think it is, softpatch weirdness maybe?


As noted by Nic above, logical process of divide and conquer; random poking about and changing stuff will increase the confusion rather than solve problems.

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Thanks for the input guys, nice to hear that you are coming up with some of the things ive tried today to solve this!!


The correctly responding LED Can is of the Lowest value.


They're all run off the same cable configuration - 5pin > 3pin with polarity coresponding with correct pin readout (Fixture manufacturer specified!) - so incorrect polarity would also give poor/ no operation over the movers & the one working Par.


Im urging more towards a desk patch fault the more I think about it - will double check operating modes of the Pars, however, have reverted them to basic set up (reset, set to 3ch operating mode, DMX to ch1 & disconnecting dimmers) to verify mode operation - which only gave operation over 3 channels (as it says on the tin!) so where is this blasted strobe attribute coming from.....??


I'm gonna give the terminators a whirl, perhaps reset desk and start again afresh.


Failing that, I might have to launch them at the floor, a gentle knock might sort them out!

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Is this issue happening when using channel faders or sub-masters? I think I vaugely remember on the Bull-Frog desk having to 'seperate' the 'intellegnt' side of the desk from the generic because of a similar problem you are discribing. The submasters would 'home' the movers and LED's, but only generics were programed on them...rather perculiar. Its a few years ago though so maybe my memory is poor and maybe the Leap-Frog is different in this respect. Jon Hole should be around soon I'm guessing.......
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Sorry to say - it will very likely be the LED Par's - the updating DMX frame with all the channel data on it is confusing them and they probably are confusing Mark/Break with channel data. Try them on a separate universe and the problem will likely go away but have only the LED's on than universe and check that your earth is good (the other problem I've seen with LED Pars).
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Jon Hole should be around soon I'm guessing.......



If you save the show file and drop it into an email for me, I'd be happy to see if anything obvious pops out in the soft patch.


Have you got the original LeapFrog (with Floppy disk drive) or the 'new' one with the USB ports?

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