blackmagicthe1st Posted December 15, 2008 Share Posted December 15, 2008 Ok I've been reading through here and have seen quite a few posts on this topic. Sorry to start another but I figured if I posted on an old one it may not be noticed. My story is one many of you will hve heard before, Its to do with a church with 2 strand mini 2 dimmer packs. I've bought a Botex Demux but need to get the cable to connect to the dimmers. I have been onto the 10 out of 10 website but by the time I would buy one from them and then have it shipped to Northern Ireland with the postage insurance etc, I've blown pretty much all of my budget. I would buy from them but my budget won't allow it sadly. I can't solder and don't know anyone willing to take on the task of making a lead up. I have notice on a few posts a few years ago now that some people might have had one of these leads around. There would be £30+p&p in it for anyone willing to offer one up. Thanks for you help guys. :P p.s bought the demux off thomann, anybody ever had any majr problems with them? Link to comment Share on other sites More sharing options...
J Pearce Posted December 15, 2008 Share Posted December 15, 2008 Are you sure you want bleecons?At manufacture Mini2s had octal sockets (big round brown things). Many out there have been modded for bleecons, but equally many are still on octals. Link to comment Share on other sites More sharing options...
blackmagicthe1st Posted December 15, 2008 Author Share Posted December 15, 2008 Are you sure you want bleecons?At manufacture Mini2s had octal sockets (big round brown things). Many out there have been modded for bleecons, but equally many are still on octals. Well one pack has been modded to bleecon, the other hasn't however I want to do that. Those octal things seem horrible! Link to comment Share on other sites More sharing options...
J Pearce Posted December 15, 2008 Share Posted December 15, 2008 Indeed they are, just thought it was worth a check that they had been modded before you got a nasty surprise. I'd recommend you give 10outof10 a call, they're most helpful chaps and they may be able to sort something regarding postage, or they may know of a similar supplier in your area. Link to comment Share on other sites More sharing options...
blackmagicthe1st Posted December 15, 2008 Author Share Posted December 15, 2008 I will do, thanks, I thought it was maybe just a standard postage that they charged and wouldn't be up for negotiation. Link to comment Share on other sites More sharing options...
Paul J Need Posted December 16, 2008 Share Posted December 16, 2008 Hi Blackmagic, You probably saw our standard courier prices - which I agree are rather high when sending stuff to NI - this is because we have lost faith in the Post office. and also since we moved 18 months ago we are not very near a post office and it takes someone almost an hour to get there, park, queue then come back......... However as you're having problems we'll do all we can to help and will take it to the post office for you when we are next passing, which is probably on Thursday. The postage costs will be a fraction of what we are charged by Businesspost let me know via e-mail at the main 10outof10 site. Cheers Paul Link to comment Share on other sites More sharing options...
peternewman Posted December 16, 2008 Share Posted December 16, 2008 Ok I've been reading through here and have seen quite a few posts on this topic. Sorry to start another but I figured if I posted on an old one it may not be noticed.Moderation: Just to clarify, you can post away in a relevant old topic you find, or create a new one if there aren't any relevant topics that already exist. If you post to an existing topic, then your new post will bump it back to the top of the forum, as the date of the last post (i.e. yours) will be newer than anything else. Link to comment Share on other sites More sharing options...
blackmagicthe1st Posted December 16, 2008 Author Share Posted December 16, 2008 oh sorry about that......... :P Link to comment Share on other sites More sharing options...
ianknight Posted December 16, 2008 Share Posted December 16, 2008 I would also warn you that using the Botex to drive Mini 2's is not a good idea. Being an old design of input stage on the Mini 2's (from the late 50's) and the outputs on the Botex driving direct from the chip outputs, you will in about 3 months find that the Botex has died. You may be lucky and find that the output chips (LM324's) are socketed so you could just buy some more and replace them - but this will re-occur every so often. I speak from experience with these units - they are a lovely way of doing cheap and reliable DMX to Analogue but we killed two units driving Mini 2's with them. I never did find the input current draw on the Mini 2 but being mainly transistors, I suspect it's higher than the couple of milliamps the LM324 can sink per output. Later racks like the Tempus work fine - the input stage on those is a more modern design. If you have some electronics expertise, I suppose you could knock together a small PCB with some high current Op amps in 1:1 mode to sit between the Botex and the Mini 2's or with some transistor buffering... Link to comment Share on other sites More sharing options...
blackmagicthe1st Posted December 16, 2008 Author Share Posted December 16, 2008 I would also warn you that using the Botex to drive Mini 2's is not a good idea. Do you think I'd get one or two shows out of it? I won't have time to do what you are suggesting but hopefully could be a project for a tech sometime? Link to comment Share on other sites More sharing options...
ianknight Posted December 17, 2008 Share Posted December 17, 2008 I would also warn you that using the Botex to drive Mini 2's is not a good idea. Do you think I'd get one or two shows out of it? I won't have time to do what you are suggesting but hopefully could be a project for a tech sometime? It's tricky to predict - the couple that we lost ran for a couple of months before the user reported problems but we're not sure (and neither were they) how much they used the thing before it started acting up. If you can place the unit close to the racks so that you're not driving down a length of multicore cable then that might help things last a little longer... Link to comment Share on other sites More sharing options...
blackmagicthe1st Posted December 30, 2008 Author Share Posted December 30, 2008 Thanks for your advice guys. Ok so just to update here is where I have got to. Demux arrives, wired it up and had a little bit of fiddling with voltages and polarities but we got there in the end.So now I have a situation where, on my desk, channels 1,2,3,4 all work but when I put up 5,6, etc. all previous channels dim. As I go further up the channels eventualy everything has gone out with all channels on. Does anyone understand what I'm trying to explain? It's nearly like the dimmers don't have enough power and as a result of another light being turned on, the other channels cant go full power. I know this is not the case though because when I plug in the analogue desk everything works fine. Could this be to do with what Ian is talking bout above? :P Link to comment Share on other sites More sharing options...
springgrove Posted December 30, 2008 Share Posted December 30, 2008 So now I have a situation where, on my desk, channels 1,2,3,4 all work but when I put up 5,6, etc. all previous channels dim. As I go further up the channels eventualy everything has gone out with all channels on. ...Could this be to do with what Ian is talking bout above? :PIt does sound as though the high current drain is pulling the voltage down. You could check whether the same thing happens if you start off with 3, 4, 5, 6, then add 1 & 2. If it does, then that's almost certainly the problem. A solution would be to build an op-amp buffer. Nigel Link to comment Share on other sites More sharing options...
mutley Posted December 31, 2008 Share Posted December 31, 2008 A solution would be to build an op-amp buffer....or it may be simpler to build a transistor buffer. Op-amps generally have a maximum current output of about 30mA (40mA on some LM324s), and it would also save having to use dozens of resistors to set them all to unity gain. It would seem that the demux probably has a limited negative supply current of about 250mA, which for most dimmers with op-amp inputs, would be plenty, but for an older, more basic, transistor input stage, a transistor buffer may be more appropriate. Being negative polarity control lines, using PNP transistors would simplify things. I'll have a play around with some bits I have lying around and see what I can come up with... :P Link to comment Share on other sites More sharing options...
Biskit Posted December 31, 2008 Share Posted December 31, 2008 Could this be to do with what Ian is talking bout above? :unsure: How old are the Mini IIs you are using? I have come across various slightly different designs over the years which I suspect represent different stages of development, still under the Mini II name. Perhaps there are minor differences to the control circuits. I occasionally work in a venue which has 24 channels of Mini IIs, and I used a Botex demux with them without problems. For the last few years I have reverted to taking my own dimmer rack there instead as it is easier, but a friend still regularly uses their Mini IIs with his Botex demux and has never reported an issue. Another long shot, but could the top-set on the dimmers need adjusting? I don't have experience doing this with Mini IIs, but I once needed to do it with some Tempus racks to get them working reliably with a Botex demux. Might be worth a try. Ben. Link to comment Share on other sites More sharing options...
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