ItsMyNaturalColour Posted May 12, 2012 Share Posted May 12, 2012 Hey everyone...I've just bought 2 Roboscan 812's for a fantastic price in a flight case. They should be arriving some time next week. Just a simple question about these lights. Do ALL 812's require a phase-reversing adaptor when using them with DMX, or is it just early models? I'm asking because I want to use these lights for a gig pretty much as soon as they arrive, and I need to know in advance about the adaptors so I have enough time to get my hands on some or make some up.Thanks,Tom Link to comment Share on other sites More sharing options...
JDLX Posted May 12, 2012 Share Posted May 12, 2012 You only need to convert the start of the chain, as far as I'm aware. Link to comment Share on other sites More sharing options...
OllieDuff Posted May 12, 2012 Share Posted May 12, 2012 I think the question was more about whether later-model 812s need adaptors, rather than whether you need an adaptor at every step in the daisy chain. JDLX's answer is factually correct, however. If it were my gear, and (I assume) second hand and not under warranty, I wouldn't bother with adaptors - hassle if you lose them. Instead, open the case up and swap the wires over on the back of the chassis mount XLR. Then put a DYMO label on it saying "DMX - PIN 3 HOT" to prevent anyone who knows about 812s getting confused. The 1999 issue of the user manual says you need to use a phase-reverse adaptor. Try to find a manufacturer's stamp or some other way of establishing its age. Link to comment Share on other sites More sharing options...
CharlieH Posted May 12, 2012 Share Posted May 12, 2012 The 1999 issue of the user manual says you need to use a phase-reverse adaptor. Try to find a manufacturer's stamp or some other way of establishing its age.Slightly OT but why would Martin design them to require an adaptor? I am guessing its something to do with an internal Master/Slave Mode....but modern fixtures do not require this http://www.blue-room.org.uk/public/style_emoticons/default/blink.gif Or am I missing something obvious? Link to comment Share on other sites More sharing options...
jonhole Posted May 12, 2012 Share Posted May 12, 2012 Slightly OT but why would Martin design them to require an adaptor? So when you're in the middle of a field, in West Wales, with no Leatherman or tools, and your hire company forget to include them, you can have fun trying to butcher a DMX cable with a carving knife from catering and some LX tape. Not that I'm bitter.... Link to comment Share on other sites More sharing options...
OllieDuff Posted May 12, 2012 Share Posted May 12, 2012 Slightly OT but why would Martin design them to require an adaptor? So when you're in the middle of a field, in West Wales, with no Leatherman or tools, and your hire company forget to include them, you can have fun trying to butcher a DMX cable with a carving knife from catering and some LX tape. Not that I'm bitter.... Less cynically, because they were designed for back-compatibility with a Martin proprietary protocol (back when manufacturers of lighting fixtures were churning out their own protocols like it was cool) which uses pin 2 as the positive signal line. Presumably it was cheaper to manufacture and sell phase-reversers than to install gubbins to detect what signal it's getting and swap contacts accordingly. Link to comment Share on other sites More sharing options...
timsabre Posted May 12, 2012 Share Posted May 12, 2012 When DMX first appeared on 3-pin XLR's, everyone had Pin 2 "Hot" - presumably following the US audio protocol. Or maybe as Ollie says Martin was keeping compatibility with their own non-DMX protocol. But all disco/club scanners of that era were pin 2 hot as well (some of those being my design, and we followed Martin). Link to comment Share on other sites More sharing options...
CharlieH Posted May 12, 2012 Share Posted May 12, 2012 Thanks to everyone for clearing that one up :) Not really important, just curious. Link to comment Share on other sites More sharing options...
Jivemaster Posted May 12, 2012 Share Posted May 12, 2012 Make yourself an adaptor lead with the crossover. Send DMX to all the pin3 hot devices, then insert the crossover lead, then wire all the pin2 hot devices then terminate. There is one convention that yellow patch leads have a reversal of some sort, so maybe one yellow DMX lead would do the job. If you don't need it really the cost isn't serious! Sometimes modding the internals is the easy way sometimes it just isn't going to work for the PCB layout. You could also look for a DMX splitter and run all the pin2 hot units off one split with the pin3 hot off another split. Link to comment Share on other sites More sharing options...
LXbydesign Posted May 14, 2012 Share Posted May 14, 2012 yeah - just make up a couple just in case, or buy them from CPC or something. I remember buying 812's new in 1999 and they were running from a Sirius 250 via Pulsar Universal Interface and I dont remember using a phase converter for them. All of the kit was bought new at the same time (from a lottery bid). Ah, yes I remember now!! (talking to myself here!!) The DMX came out of the Sirius250 into the demux - analouge 24 channels out to the dimmers and DMX (5pin) out to the scans - using a 5 pin - 3 pin converter which was also phase reversed!!! Link to comment Share on other sites More sharing options...
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