allymoss Posted September 10, 2007 Share Posted September 10, 2007 I have 4 dimmer packs, (12 sockets, 6 channels in each) DMX cable from laptop (I use PC Stage) goes to top dimmer, and they are linked together daisy chain. The bottom one is usually where I plug another cable in to go to my 2x ACME spotknight mh-664 moving head. The cable I use is a 5pin DMX to 3pin, then just standard longer 3pin XLR to the device. Anyway, dimmers are all working fine until I plug this wire in. As soon as I plug in, the little red "error" LED comes on and then all the other dimmers do the same. I cant control the ACME's or the lights at all! Is this a cable problem?? I don't get much time with them so ideas before I go would help. I have wired it before like this and had no problem. I dont have a DMX cable tester but I have XLR tester. Also, strange thing is when I do plug in, they stop doing their standard inbuilt show and go to rest position, so there is a connection. This is Kind of urgent as I will only get to check again tommorow and perhaps the next day! Thanks for all your help Link to comment Share on other sites More sharing options...
Andrew C Posted September 10, 2007 Share Posted September 10, 2007 Sounds like one of your bits of kit needs to have the polarity reversed, or you have a swap lead and don't need it. I'll go now and delete the duplicate post! Link to comment Share on other sites More sharing options...
allymoss Posted September 10, 2007 Author Share Posted September 10, 2007 Hi, What do you mean needs polarity reversed? We did have the electricians in to do some testing about 30 mins before I used them could this have anything to do with it. I need the swap lead because the dimmers have male 5pin DMX and the acme device has female 3pin! I had to use a converter Thanks for deleting other post, didnt realise! Link to comment Share on other sites More sharing options...
niall Posted September 10, 2007 Share Posted September 10, 2007 em, I very much doubt polarity should need reversed. Plugging a piece of equipment that needs a "pinswap" adapter will pass the original signal through without any problems, it just won't operate. It sounds more like there is a short somewhere, either between 2 pins, or between a pin and the XLR chassis. Link to comment Share on other sites More sharing options...
allymoss Posted September 10, 2007 Author Share Posted September 10, 2007 so its a wire problem? I have loads of wires to change and test but just checking whether it could be something more serious! Link to comment Share on other sites More sharing options...
JimWebber Posted September 10, 2007 Share Posted September 10, 2007 Hello, At the risk of stating the obvious, what XLR cables are you using? Are you using proper data cable? Microphone cable is renowned for causing DMX data errors! Similarly is the line terminated? again, an un-terminsted line can cause all manner of problems! HTH On re-reading your post, you say electricians were in testing - Were they PAT testing your kit? Jim Link to comment Share on other sites More sharing options...
allymoss Posted September 10, 2007 Author Share Posted September 10, 2007 Hi, Yes we only have standard 3pin XLR's, we don't have any DMX 3-pins which is a shame, whats the difference by the way? Line is terminated, I made my own today, quite neat, 120ohm 0.5w resistor across pins 2 and 3 on spare DMX/XLR plug Electricians were not PAT testing kit, just the main electrics, the "big" stuff, fuse boxes etc. PAT testing is a real pain! Every light has to be taken down for them, every extension cable, lead anything associated with power because in schools and public places they take no risks, although thats not till November! Few I will try a few more cables tommorow and report back Link to comment Share on other sites More sharing options...
iamchristuffin Posted September 10, 2007 Share Posted September 10, 2007 DMX cable and mic cable are technically different. But; in real life, the differences are often negligible. You will probably get away with it if you use the wrong one. Are your DMX and Mic cables not marked as being different in any way? If not, find out which is which and mark them yourself. Telling the difference between DMX and mic cable is tricky, but as a general rule of thumb, DMX cable is usually plastic coated, stiffer than Mic cable and a bit thinner. Mic cable is rubber coated, a bit more flexible, and thicker. A quick turned these out. It's not the connectors, it's the cable in the lead! PAT may be a pain, but it should still be done, especially in a school environment. Link to comment Share on other sites More sharing options...
paulears Posted September 10, 2007 Share Posted September 10, 2007 And they make a fair few quid out of it too! Although many of us disagree, I have never had any issues using decent mic cable for DMX. Link to comment Share on other sites More sharing options...
allymoss Posted September 10, 2007 Author Share Posted September 10, 2007 Well our school budget for equipment is £0 a year although we have a contract with HSL to put lights up etc as we don't have anyone with qualifications yet! I will see if I can tell tommorow about the mic/DMX cables, are the mic ones shiny because all our cables are dull black. I know PAT testing has to be done but still takes ages, last year, they had to come back 3 times because they forgot loads of stuff each time, even though it was laid out in the hall in order of size type of everything! I suppose its a good time to re-organise everything. Link to comment Share on other sites More sharing options...
iamchristuffin Posted September 10, 2007 Share Posted September 10, 2007 I don't know of any cables that are 'shiny'. There are some that are 'more plastic-y' than others, but this doesn't really mean anything (possibly not as good quality?) If there's no-one with qualifications, who 'runs' crew at your school? Link to comment Share on other sites More sharing options...
Jivemaster Posted September 10, 2007 Share Posted September 10, 2007 Remember that the DMX line needs terminating once! Look at the last (in DMX wire order) dimmer to see if it has a switched terminator switched on. If so insufficient DMX will; get past to drive the next items, Link to comment Share on other sites More sharing options...
allymoss Posted September 10, 2007 Author Share Posted September 10, 2007 Very good idea, over the summer HSL have come in and taken our strand lighting desk, which we don't use for shows but inbetween stuff and they also changed a load of channels and lights plugged into dimmers which is REALLY annoying. So tommorow I will check to see if the terminator is switched on on the dimmer and if so, turn it off! In answer to the post by "iamchristuffin" No-one really, I am the person that does all the lights and I have employed 2 other helpers to do sound and stage management. There was a teacher that had qualifications to put lights up etc but left last year, HSL come in before any shows, I have to have lights ready for them and once up thats it, we can't even move them or change filters. So in answer to your question, Me but I can't put lights up in high places! Link to comment Share on other sites More sharing options...
iamchristuffin Posted September 10, 2007 Share Posted September 10, 2007 In answer to the post by "iamchristuffin" No-one really, I am the person that does all the lights and I have employed 2 other helpers to do sound and stage management. There was a teacher that had qualifications to put lights up etc but left last year, HSL come in before any shows, I have to have lights ready for them and once up thats it, we can't even move them or change filters. So in answer to your question, Me but I can't put lights up in high places! Understandable, with the H&S that's in place. Not to be a killjoy or a hypocrite, but I'm a bit surprised you're allowed at the dimmers either, without any supervision. Also, how do you employ people if you're still (like me) a student? Link to comment Share on other sites More sharing options...
allymoss Posted September 10, 2007 Author Share Posted September 10, 2007 When I say employ, I mean they want to do some tech stuff and I teach them and they do it, they know what to do now. As for the Dimmers, I was told by the person before me I wasn't allowed but he did it anyway. On the safe side I was going to ask the Adult in charge and forgot basically. Anyway one day she say go and turn power on up in the lighting box, and I say am I allowed and she goes sure. So I can turn them on and off and plug DMX leads in but not much else. Link to comment Share on other sites More sharing options...
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