stuartw154 Posted April 16, 2014 Share Posted April 16, 2014 Hi, just patched a Zero 88 Leapfrog to some analogue dimmers via a showtec multi-exchanger. The desk is patched 1 to 1 and the showtec DMX starts from 001, however the lights are not coming up 1 to 1 but coming up in a random patch and channel 2 when pushed to full dips the level of any other channels currently on. Anyone had a similar issue? Thanks Link to comment Share on other sites More sharing options...
themadhippy Posted April 16, 2014 Share Posted April 16, 2014 What make of dimmers? not pulsar by any chance Link to comment Share on other sites More sharing options...
Don Allen Posted April 16, 2014 Share Posted April 16, 2014 I suspect it could be a wiring problem.Some demultiplexer connectors have the channel numbers running across the top then across the bottom, some alternate the channel numbers so you have odd channel numbers across the top and even channel numbers across the bottom. The common can be on different pins as well.There have been a lot of posts over the years on demuxes or multi-exchangers.You need to find wiring details for the dimmer as the Showtec multi-exchanger is on the case. Link to comment Share on other sites More sharing options...
PaulDF Posted April 16, 2014 Share Posted April 16, 2014 The showtec multi exchange has a strange pinout for the outputs, I think there is a diagram on the back. Ch1 = Pin 13 Ch2 = Pin 25Ch3 = Pin 12 Ch4 = Pin 24Ch5 = Pin 11 Ch6 = Pin 23 Ch7 = Pin 10Ch8 = Pin 22Ch9 = Pin 9Ch10 = Pin 21Ch11 = Pin 8Ch12 = Pin 20Ch13 = Pin 7Ch14 = Pin 19Ch15 = Pin 6Ch16 = Pin 18Ch17 = Pin 5Ch18 = Pin 17Ch19 = Pin 4Ch20 = Pin 16Ch21 = Pin 3Ch22 = Pin 15Ch23 = Pin 2Ch24 = Pin 14Earth = Pin 1 Link to comment Share on other sites More sharing options...
Brian Posted April 16, 2014 Share Posted April 16, 2014 Is your DMX polarity right? Link to comment Share on other sites More sharing options...
kgallen Posted April 16, 2014 Share Posted April 16, 2014 1. The 25-way connector pin out has caught me out before, definitely worth a check.2. Check if dimmers take a negative control voltage (are they Strand?).3. Check the 8-DIN pinout at the dimmer end as suggested above (Pulsar are different pinout to Strand/Zero88).4. Check there is not a non-1:1 patch set up on the desk - this wouldn't cause the channel 2 problem, but worth a check. Kevin Link to comment Share on other sites More sharing options...
ianknight Posted April 17, 2014 Share Posted April 17, 2014 It's more than likely the multi connector on the back of the Multi Exchanger - we've had our share of customers pulling an old one from their "odds & sods cables" box and plugging it then whining that things don't work. Strand foresaw the issue when they badged the unit and produced some nifty adaptors that did the pin swapping for all those customers replacing old D54 demux boxes. Link to comment Share on other sites More sharing options...
stuartw154 Posted April 17, 2014 Author Share Posted April 17, 2014 Many thanks for the replies.......... The dimmers are electrosonic and are quite old, mid 80s vintage I believe, and I have the polarity correct.I suspect the issue is with the multi-connectors, having read the posts, it would make sense that that's where the problem is.I'll see if I can find the specs for the dimmers and compare......... Link to comment Share on other sites More sharing options...
stuartw154 Posted May 4, 2014 Author Share Posted May 4, 2014 Update for those who helped and those seeking info........... The issue was with the 25 pin connector, the ones to our dimmers are configured 1 to 1 but the showtec outputs are configured as per the post by PaulDF in this forum. The reason channel 2 was dipping the output was because it was, (thanks to the showtecs odd configuration) patched to pin 25 which is the earth pin. So rather than rewire the whole thing I just soft patched the Leapfrog. Thanks for everyones help.......... Link to comment Share on other sites More sharing options...
PaulDF Posted May 4, 2014 Share Posted May 4, 2014 As long as earth is pin 1 you should get away with soft patching, otherwise you can still end up with strange results.For a quick way of getting the right outputs with an older desk I bought a few of these kits: http://cpc.farnell.com/mh-connectors/mhga2525mflgk-rc/gender-changer-custom-d-25p-s/dp/CN04539?Ntt=CN04539(I got a few to make sure I had enough through links). I know it says gender changer in the title but they are 25M to 25F, gender changers M-M and F-F are available too. Link to comment Share on other sites More sharing options...
kgallen Posted May 5, 2014 Share Posted May 5, 2014 You might get some weird problems the more channels that get turned on or the higher their level, because the current will be trying to return via a pin that is not a true ground, but rather the output stage of another channel that happens to be low.In emergency use the patch, sure, but get the wiring sorted out at the earliest opportunity, and I wouldn't risk a show with the workaround myself!Kevin Link to comment Share on other sites More sharing options...
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