jcblincs Posted January 24, 2009 Share Posted January 24, 2009 I know that technically you should use a 0.25W 120ohm resistor but I dont understand why a 0.5w resistor is not advised ? the power rating is surely the max power the resistor is stable up to. So by using one of a higher rating it will not make a difference will it ? Link to comment Share on other sites More sharing options...
gareth Posted January 24, 2009 Share Posted January 24, 2009 On the contrary - a 0.5w resistor *is* advised. If you work out the maths, a terminator will potentially be handling more than 0.25w so you should be uprating it to 0.5w. Link to comment Share on other sites More sharing options...
jcblincs Posted January 24, 2009 Author Share Posted January 24, 2009 now I am confused. the wiki article says use 0.25w and the appliance instructions for my new kit say 0.25. on here I read someone say not to use 0.5 as it must be 0.25 ?? Link to comment Share on other sites More sharing options...
gareth Posted January 24, 2009 Share Posted January 24, 2009 You can get away with 0.25w - indeed, many people regularly do. But if you work it out mathematically, by rights you should be using 0.5w as the termination resistor has to dissipate more than 0.25w. But hey, more and more people aren't even bothering to terminate any more, so why worry?! Link to comment Share on other sites More sharing options...
jcblincs Posted January 24, 2009 Author Share Posted January 24, 2009 I stand corrected - the wiki article says 0.5 not 0.25. my mistake why would you not terminate ? it cost about £3 for the resitor and XLR plug and takes about 5 seconds !!! Link to comment Share on other sites More sharing options...
Davethsparky Posted January 24, 2009 Share Posted January 24, 2009 why would you not terminate ? it cost about £3 for the resitor and XLR plug and takes about 5 seconds !!! I guess some people would rather save £3 than avoid wasting hours fault finding their DMX network. Link to comment Share on other sites More sharing options...
jcblincs Posted January 24, 2009 Author Share Posted January 24, 2009 why would you not terminate ? it cost about £3 for the resitor and XLR plug and takes about 5 seconds !!! I guess some people would rather save £3 than avoid wasting hours fault finding their DMX network. :) ;) Link to comment Share on other sites More sharing options...
niclights Posted January 25, 2009 Share Posted January 25, 2009 why would you not terminate ?It's not always so practical in touring rock'n'roll. They are small things that easily get lost. Load-in and out's happen fast and with equipment flying around everywhere. Chances of a terminator making it from the end of one show to the next are slim. And many devices now self-terminate anyway. Link to comment Share on other sites More sharing options...
johnlinford Posted January 25, 2009 Share Posted January 25, 2009 Additionally, because of the way termination "helps" the signal, if there are problems elsewhere in the signal chain (eg a dodgy cable), it will often work fine with no terminator and "break" when a terminator is plugged in. Obviously ideally you should then find the faulty cable, but if your gig isn't very long then this may be impractical either in terms of time or rig... Link to comment Share on other sites More sharing options...
johnhuson Posted January 25, 2009 Share Posted January 25, 2009 And many devices now self-terminate anyway. Is this really the case though or a popular misconception? As far as I'm aware Martin, Robe & High End all recommend a terminating plug be connected at the end of a DMX chain. Do you have any examples of fixtures which do to satisfy my curiosity? Link to comment Share on other sites More sharing options...
dosxuk Posted January 25, 2009 Share Posted January 25, 2009 why would you not terminate ? The same reason people use mic cables - when it's set up, it works. Only when they hit problems do people start going "Is there a terminator on that line?", or "Has someone put a bit of mic string up there?". Permenant installs there's no excuse not to do it properly, and it's sad but true, on temporary events where it only stays rigged for 6 hours, anything goes as long as it works. Link to comment Share on other sites More sharing options...
JDP Posted January 25, 2009 Share Posted January 25, 2009 Oh come on.... I have never ever seen ANY rental companies send out DMX Terminators within a data trunk.... Maybe one or two do it (and bare in mind you talking to Mr.Anal here) but we never ever have. All DMX issues I have come across since the Mid '90s (ie more than 10 years) have been down to either the cable not working properly, or a fixture problem. I have never ever experienced a case when a terminator has been plugged in and everything miraculously works again.... Also, I have found some terminators to do more harm than good - in fact, on I came across got extremely hot and the fixtures were going dolally. Link to comment Share on other sites More sharing options...
boatman Posted January 25, 2009 Share Posted January 25, 2009 ..Do you have any examples of fixtures which do to satisfy my curiosity? The Source Four Revolution has been this way since 2007. The manual is here and if you look at page 4 you'll see how it's done. Link to comment Share on other sites More sharing options...
grizzly Posted January 25, 2009 Share Posted January 25, 2009 ... and if you look at page 4 you'll see how it's done. Not really. It just says that termination is required on pre-2007 Revolutions, but post-2007 units have self-termination. No indication of how the self-term is implemented. Link to comment Share on other sites More sharing options...
niclights Posted January 25, 2009 Share Posted January 25, 2009 To be fair I don't know which fixtures have this, but I do know I can't remember seeing a terminator used on tour, ever. As I understand it is usually achieved either by a manual switch or automatically via switch type XLR sockets. Link to comment Share on other sites More sharing options...
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