Random flickering on Ion universe 2

Our older Ion is out on an infrequent hire job this week with a local guy, and I had a phone call from him last night asking if we'd had any issues with there being random flickering on some fixtures in the past JUST on universe 2. He was having some problems, but said that he'd tried them on uni 1 and they were fine. At this point I don't know if he just swapped the cables out and re-patched to prove this or if he physically patched them at the fixtures to prove it. I've suggested a few other basic fault-finding routes but haven't had more feedback as yet.

However, for the point of this question that's irrelevant. What I'm interested in is whether there is a likelihood/possibility that the desk itself might have a fault which could output 'dirty' DMX data and hence cause the symptoms?

In my experience, issues like this tend to be a dodgy or unsuitable cable, lack of termination or electrical noise on the line either from an external interference or a faulty fixture somewhere on that line. I've not heard of a desk generating noise etc...

I'm trying to help diagnose remotely - and have suggested he give the hallowed ETC support a call last night - so don't have all his details as yet, but just pondering the desk possibilities just in case.

So - thoughts?

  • If he has any long runs on U2 did he terminate them with 120 ohm loads? I agree with you regarding the placement of electric and DMX cables - long runs with them side by side (especially if they are using XLR cables can be a recipe for problems. 

  • I don't have full details of his rig setup so can't comment until he replies to my questions (and yes terma was one of those questions).
    But as I say, that sort of thing should be traceable IF there are cable/kit/fixture/interference elements...

    But my question is whether it's feasible for the desk itself to be sending corrupt or noisy data...

  • Flicker is a fairly common issue if RDM is enabled and the fixtures aren't tolerating it.

  • Hmmm... 

    Doubt it is enabled (by choice anyway) but would that affect just one universe??

  • It can affect one universe in a couple of ways:

    • it can be enabled on a per universe basis in Settings
    • if it's enabled for all universes and the fixtures on one universe tolerate it.
  • RDM can be enabled/disabled on a port by port basis.  If he was trying Universe 1 by moving the cable, then the settings on the port would have remained unchanged.

  • Well, finally got some feedback from the hirer and as expected it was NOT a desk problem but a rogue cable issue - which is what I suggested they investigate first.

    However, some interesting thoughts from you guys on the potential for flicker-fest causes, so something to ponder for the future.