Icue - Rosco - Twitch ?


Hey out there,

Has anyone experienced a slight twitching in Rosco ICue mirror units? I have two, and both of them on this rig are constantly twitching. It is not the actual units as I swaped them out with new ones. Power..DMX ??



Senior Team
Senior Team
Fight Leukemia
Off the top of my head...

Could be something weird in the power supply unit. Try swapping it out with another one.

Do you have other DMX units in addition to the I-cues and no DMX terminator? Or do you have I-cues on two or more power supplies without a DMX terminator? Could be reflections in the line. The I-cues don't need a terminator but if they are all alone on one power supply. However if the line goes from the power supply off to something else you could get some weirdness that way.

Is it real high quality 5 pin DMX cable running between the DMX out and the power supply unit? Cheap home made XLR cable conversions can do weird things.


Thanks for the reply,

All the cable is 'high quality', and the power supply is only running the two I-Cue units.

However there is no termination - I thought the I-Cue units did not require this. The DMX runs directly out of my board (Strand 520) on a 100' to the first unity, then to the second (25' run).

I will swap out the power supply later today, to eliminate that.

Try terminating the dmx, and or swapping out dmx cables. Dmx problems can be a huge pain and hard to track down, I've had dmx porblems with dimmer packs that caused the lights to flash, which it you translate that into the way the i cue works would equal twitching. The dmx prob may not be at the power supply it could be up the line at a dimmer or something else.
hope this helps.


The DMX standard specifys termination for any cable run, regardless of length or number of fixtures. Yes you can get away with not bothering a lot of the time, BUT twitching fixtures is a classic symptom of an unterminated line. Try terminating the DMX, if that doesnt fix it you can then ring Rosco and gurn at them!


CB Mods
Premium Member
I wholeheartedly concur with Andrews assesment. Twitching, in almost any Intelligent fixture, is best first addressed by looking at your DMX. You can look at other threads on here and find that I'm a DMX termination Nazi. If you don't have terminators at the ends of your runs you cannot move forward to any other trouble-shooting proceedures until you do terminate. Terminators are simple, cheap, and using them will only help you. The only problem I have ever seen, that was caused by a terminator, was when one was improperly or poorly constructed. I do not understand the great number of people in this business who still don't understand or get confused about terminations on DMX. $10.00 in parts can save you hundreds in man hours of running around pulling your hair out.
I actually was about to post a thread about this when I saw this, we had exactly the same problem today, and we also traded out the I-cue but also the power supply, and we had a terminated dmx run. we ultimately decided it must be something in our shownet system, I wonder if it is inherent in strand DMX refresh rates? either way all of our I-cues have the same problem, it is very annoying.

If you figure out how to get it to stop please let us know.
We traded out three differnt power supplies, both rosco and apollo versions (and i know that rosco does not recomend using apollo, but we have not had problems with it) we also tried repatching and have not had any luck. So far we have been able to root the problem back to the shownet node. The next step tomorrow will be to home run a dmx to our hog and see if we have the same issue.


Apollo Staff
Premium Member
<and i know that rosco does not recomend using apollo, but we have not had problems with it>

That's a simple one. The Apollo PSU's are just about bulletproof and an exceptional value, which is probably why you've heard this. :)
Four pin circuits for scrollers and other accessories (EXCEPT Wybron ColorRam systems) use 24 Volts DC on pin 1 (-) and pin 4 (+), with data on pin 2 (-) and pin 3 (+).

The four pin circuit is intended to work well with similar accessories, as long as the components use the pins in the same manner. The Wybron ColorRam uses a different pin configuration, preferring to work instead with other ColorRam components.

When in doubt, return a four pin cable back to the PSU to complete the circuit and boost line voltage...
So we eneded up bringing a Smartfade up to our cat and trying that on the DMX line and the twitching stopped. We then tried it back on the net and it twitches again, so we are going to investigate further with shownet. We also seem to be experiencing other problems with it as well, so it may just be phantom packets.

In addition Kelite, thank you very much for that clarification, we generally use the Apollo power supplies on all of our accessories, they are extremely reliable. We also always run return lines as a matter of course.


Apollo Staff
Premium Member
<In addition Kelite, thank you very much for that clarification, we generally use the Apollo power supplies on all of our accessories, they are extremely reliable. We also always run return lines as a matter of course.>

Yes, the PSU's are built very tough, and the return line is a good habit to get into. Thanks for letting us know the results of your efforts!
Dredging this back up because of new information.

We recently got word back from our Strand supplier who took a look at our system a few weeks ago that we had a corrupt showfile in the 300 series, apparently it is a common problem and produces both nods in MLs and a flickering in convenentionals and seems to be related to the volatile memory, although that would not explain PJC's problem with a 520. anyway thought I'd let you know how it turned out.


Apollo Staff
Premium Member
<we had a corrupt showfile in the 300 series>

So did your I-Cue twitching problems then go away?

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