Dimmer Pack Signal Cable Prob...need advice asap.


In the small(599 seats) theater i work at, the forence shwimmly little theater, we use four stand cd80 analog dimmer packs(12 dimmers a pack for a total of 48) from the 80s, the school has them stamped as being bought in 1988. Our signal cabels like to do random things and make everysingle light in the theater (including house lights, there on the same packs) ghost and flicker competely randomly. Our board is an ECT express 48/96 and we use a digital to analog converter to plug into the analog packs. Normally when we have a ghosting or flickering problem we restart the packs, or jiggle the signal cable, or restart everything. This usually fixes everything, as the heads of the signal cabels are loose and electrical taped togethor and in place . This is normal, just like our patches loverly smell that lets us know things are working. Today when i went in there to get ready for a film festival, the house lights were flicking and ghosting. Up on the board they were up at full, so i restarted, jiggeled everything and our lighting designer and i were working on it for 45 minuets. We conclueded that there is a short in one of our signal cabels, and that they are just borken. They would have been replaced a long time ago but no one bothedrd to look for them. Now that we have no controls over the lights and our light controls are circut breakers on the packs. we are forced to find new ones. I keep looking online, but im only findinding the new CD80 packs that are digital, and therefor dmx, which isnt compatible with our packs. Does anyone have any advice or know where i can get new cables. we cant really soder them beucase we already did a while ago, and never want to again, because soddering a 5 pin cable thats a bit bigger than a cenemiter in diamater is just annoying. Any help is greatly appreciated.
arent they just amx cables?
i would suppose so. Im not really a lighting person nor an electricty person. Being colorblind I never boherd to learn much about lighting(gells are impossile) If these are AMX cables, where would i find them? i google and froogle searched and only found the AMX to DMX converters, of which ours is fine. I havent called strand about it yet, but i couldnt find a number on the site.
it could be amx or it could be some other amalgam of 0-10v analog

It's a bit peculiar that the packs wouldn't also be able to accept DMX, as I think the cd80s have always been able to take DMX, AMX, and 0-10v analog. Who knows, maybe you guys got the bargain basement one...:p

Amx is typically a four pin xlr, dmx is a 5 pin xlr (usually). Amx was in an era of strange standards, though, and there are things out there with parallel port outputs, and other weird things.

What kind of converter do you have, and what is the output? If it is four pin XLR out, you should be able to just pick one of those up at a local supply house.
I dont know about what the converter is, but i know it goes from dmx to a tiny (about 1 cenimiter) in diamiter plug with 5 pins in it, its like the mini xlr on shures beta 91 mics, except 5 pin insted of the 4 or 3 on those. These cd80s are made pre dmx standard, and the fact that my school aquired them in 1988(or recored them existing) doesnt mean there from 88. Al the hard wiring in the theater is about 50 years old, they theater has not had any major renevations since then. That doesnt mean much as we could have gotten the packs later, if i were to guess there about 20-25 years old. As i said, im a sound guy but as far as i know dmx wasnt aroudn then. These packs only have 2 plugs on the front of them, both in this cenimiter wide 5 pin analog cable. the 2 plugs are used to daisy chain the packs. Im just stumped, and our theater manager is out of town fior the week, while we have stuff in there every day.
From what you described, and having used CD80's since near they were first made, my first thought is its not the cable but probably the pack-brains or in your converter before I would say its in your cable--and its a a ground leak issue is what comes to my mind. See for ghosting and flickering, there is something sending it or giving it a false data opr voltage signal--now that could very possibly be power/AC electricity related. Now not being there or seeing your symptoms or being able to troubleshoot this myself, I can only speculate--but that is what it sounds like to me. Do the packs flicker and ghost with the console OFF? If yes--check your signal converter and your CD 80 packbrains (they may be dusty after 1988 ;) ) If they flicker while the converter is still on and the board is off, unplug your converter from the pack--does it re-occur? If yes--it is a power/ground issue feeding the CD 80 packs or in the CD80 brain itself (which IS a common thing with those older packs). If no--check your converter. Now it should benoted that some converters, even when off--can still tie the grounds between the cables-so any voltage trickle on the ground could still transmit. To check the CD80 brain for dust interference--the brain is the little slide-tray in the front of the rack. Power the rack down and it pulls right out when you loosen the set screws--dust it off and check it out--it should be connected by 2 or 3 ribbon cable connectors inside. Blow out the tons of dust from decades before very well, and put it back and see if that fixes things...

Now, Changing brains in the old packs from AMX or Analog to a DMX conversion IS possible in most of the older racks.. I believe its Johnson Systems that makes conversion kits if I recall. Do a google search for "Johnson Systems CD 80 conversion kit", as I don't have the link on this PC. Its a bit costly of a couple thousand $$ for all your packs, but its significantly faster and cheaper then the 10's of thousands or more you would spend in new racks & installation. You can then lose your converter and run your ETC board and packs via DMX...

If you still feel this is a cable issue--I still say this has something to do with the ground and that is what you chould check first. AMX was noted by the round XLR type 4-pin connector (the exact 4-pin connector used on clear com headsets and many other things)...but older true analog signals (0-10v) were sent using a CJ multipin connector (CJ means Cinch Jones, for anyone old enough to remember what those looked like). Its a wide flat thick plug with little metal tabs on it for pins..and it rattles when you shake em :lol: . Those style CJ cables were suceptable to ground leaks and loose wire connections and signal problems over time. CJ connectors and cables can still be purchased thru some vendors..and some vendors who have been around forever have some in their inventory they can loan you to test the cable-bad theory. But again my feeling is a ground issue--is your converter on a different power source then your dimmer racks? If so--try moving the converter to a same-ground source or meter the power between ground and neutral in the AC plug--it should read less then a few millivolts..however if it reads over 1 or 2 volts or higher and fluctuating on ground/neutral, that old analog or AMX connections would be VERY susceptable for that kind of interference.. Had a new air-handler Air conditioner unit put in your building recently? This kind of voltage leak can occur when new Air Conditioners or other air handling units get installed in a building and the electricians tap to make a "delta phase" connection for power and don't isolate the ground, and that can put a slight trickle of voltage down the ground.. Change your converter or isolate the power for your converter and see if that cleans up your flickering problem. (Do NOT cut the ground--that is not a solution). Round XLR or cannon style AMX cables can be bought on order from most vendors--and the 4 pin connectors can be found at most supply shops or online. Off the top of my head--both Markertek (markertek.com) and Arcade Electronics (same .com) stocks those connectors, and for a fee they will make you a cable...

Hope this helps and gives you some ideas to check out.... Post back with questions...let us know how it goes.

Well, the converter is in the booth, and the packs are stage right by the patch, so i would suppose that they are on different dicruts and everything. When either the board or converter is off, all the lights are off and we dont get ghosting or flickering. When there both on it flickers like. The lighting designer said this happend aboout 2 years ago, and required resodering some of our signal cable, also we do randomly get ghosting and flickering, which requires us to jiggle the signal cables into place, which usually fixes it, thats why we suspect the cable to be the problem. Ill see about checking the brains. I know we did ahve to take the packs apart a few years ago due to what someone thought was a borken something inside which turned out to be a flipped circit. Ill see about the brains though. I jsut unscrew the front face of the pack? We have basicly unpluged, repluged and restarted everything. The only thing that ever has had problems are the signal cables, the packs have always worked fine. Our theater was built in 1930 something, and actually doesnt have a real ground, as in the grounding pins in our 3 pin patch and circut system actually doesnt do anything. Would this possibly contribute to the problem?
The actual ground is a seperate topic and not related to this problem you have. Bring it up as a seperate topic because if you have a neutral, your theater has the potential for a ground. I kind of doubt that none of your system is ground but have no doubts that much is not which is a bad thing.

I'm thinking that if wiggling the plug often fixes the problem your problem is in the plug. You mention a past repair to the plug. (?5-pin Din) Very easy to make a repair and cause more problems in doing that repair. Since your control cable has not moved or in theory nothing has cut into it, I would find it unlikely that the entire control cable needs replacement. Otherwise if in the control cable, jigging the plug would not fix the problem. For me it seems as if you need someone to open up these or this plug and re-solder it to a better standard.

Any theater supply/service center should easily have people that can do this repair, much less give your packs a service call. Shouldn't cost that much money either. I innitially thought ghosting dimmers also. On the converters to DMX, I agree with Wolf, these dimmers just because they are old does not mean that if they are maintained, that they won't last another 27 years. I'm sure Wolf and I would agree in some way that 1988 does and will never mean old. Conversion to DMX control can be easy but if your system gets fixed there is no real reason to convert. E-Bay would be my initial choice of the conversion kits.

By chance today I was looking for some 27 pin Cinch Jones plugs. I normally stock the gambet of them sometimes with assemblies pre-wired from four to some huge number of pins saved from the old equipment I refuse to toss out. Also did a lot of repair work on our current 37pin Socapex for 8-channel DMX signal. I much prefer the strain relief of a Soco over that of a Cinch Jones. Very easy to yank wires when disconnecting and having gremlins in your system because of lazy people un-plugging them. Yep, I would have a service call to the plug(s). Cable's probably fine it's just the plugs no matter the type.

Finally, what do you mean you do sound but don't know how to solder? I'm thinking that you need to find instruction in this as it's a priority for your field.
I do know how to soder, i just dont know what would need to be sodderd to what as ive never looked at the connectors very very closely. However when we went into the theater today, everythign was working fine, excpet even with our board patched one to one and the settings on everything that has them it was one to one, and each dimmer was one dimmer to hight(ie dimmer 13 was comming out as dimmer 14 on the board.) The resuleted in our underbalcony house lights being cut as they are dimmer 48 of 48, and are therefor bumped to a nonexistant 49. I assume this is a related problem, due to the fact that its still somethings bewteen the patch, pakcs, converter and board and how they talk to each other.

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