tonytech Posted July 2, 2018 Share Posted July 2, 2018 Over the weekend I had a pipe with 6 Chauvet Colarado 1Quad LEDs on. All in 10 channel Tour mode. on its own feed from a DMX isolator/splitter.I tried to fix an initial problem (later found to be a dodgy cable) by adding a terminator, Yes. I'm lazy and rarely use terminators except on very long runs.After replacing the cable one of the fixtures in the middle of the loop in loop out DMX chain simply refused to respond. Remove the terminator (at the end of the chain3 fixtures away) and the fixture responds again.It was just the one fixture, all identical, bought at the same time 2 or 3 years ago. Anyone come accross this before? I come from an electronics background, understand DMX theory and this doesent make a lot of sense.Thanks.Tony Link to comment Share on other sites More sharing options...
timsabre Posted July 2, 2018 Share Posted July 2, 2018 Usually when you get a bizarre set of symptoms like this there are 2 faults occurring, requiring 4x the brain power to understand, but I can't really work that one out. When things die after a terminator is added, it usually means the DMX is one-legged. It'll normally work like that without terminator since the disconnected leg floats, and the connected one goes above and below it which allows the receiver to detect the signal. But when you connect a terminator that links the disconnected leg to the connected one and there is no longer any differential for the receiver to detect. However that would normally affect all fixtures after the break. I have had colorado fixtures behave very oddly or crash after a faulty DMX situation and need repowering to restore normal function, might you have removed the power while changing the terminator? The only way to be sure what's going on is to get an oscilloscope on it, but even if you had one with you, there's never time in an event situation. Link to comment Share on other sites More sharing options...
tonytech Posted July 3, 2018 Author Share Posted July 3, 2018 Thanks for those thoughts.I did cycle the power on the fixture (and the ones after it) after fixing the initial DMX lead problem, but not after removing the terminator.Show is in a couple of days, then 3 days to end of school tem.... I'l have a propper look then. I have a scope, just need the enthusiasim to use it...I'm always reluctant to investigate a "fix" for fear of completely buggering things up...T Link to comment Share on other sites More sharing options...
timsabre Posted July 3, 2018 Share Posted July 3, 2018 OK would be interesting to know, if you test without terminator at the problem fixture I bet you find data on one of the DMX legs but not on the other. Link to comment Share on other sites More sharing options...
DrV Posted July 3, 2018 Share Posted July 3, 2018 If it's not a missing leg inside the fixture I'd suspect a ropey receiver chip in the fixture. When you add a terminator you reduce the signal amplitude a little too and it may be the chip stops seeing it. Link to comment Share on other sites More sharing options...
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