Stutwo Posted October 13, 2007 Share Posted October 13, 2007 Wonder if anyone can help on this one. The College I work at has 6 Dimmers, 1 digital Act 6 and 5 Tempus racks fed by a Demux, all controlled by an ETC Express 125. This last week we needed some extra circuits in a particular spot, so added a Zero88 DMX Alpha pack in the chain, set the address to 7 on the pack, and unplugged the second dimmer from the demux. All well and good, it all works, but for some reason the Alpha pack will not fade smoothly, it will (inconsistently) flicker either on the way up or down. The pack is currently between the ETC and the Demux, the demux is behaving perfectly, it's the Alpha pack that isn't. Anyone any ideas? Link to comment Share on other sites More sharing options...
ceecrb1 Posted October 13, 2007 Share Posted October 13, 2007 It's not something so simple as dirty faders is it? Link to comment Share on other sites More sharing options...
pritch Posted October 13, 2007 Share Posted October 13, 2007 If you use the faders on the front of the Alphapack, does it fade smoothly then? If it fades smoothly using the faders, what happens if you plug it into the desk as the only item? Any improvement? Link to comment Share on other sites More sharing options...
Stutwo Posted October 13, 2007 Author Share Posted October 13, 2007 The Alpha pack faders give smooth fades, and the flicker occurs regardless of whether you pull down the master or the channel, even if the pack is the only item in the chain, and strangely also happens on all of our four DMX alpha packs, we tried each in turn to make sure it wasn't a problem with a single pack. The DMX cabling has also been changed. I've never seen anything like this before. Link to comment Share on other sites More sharing options...
James Remo Posted October 14, 2007 Share Posted October 14, 2007 Could it be the timing of the DMX? On a pearl you can "slow down" the DMX refresh rate. We have had to do this in the past to get alpha packs to work correctly. From the pearl manual:This User Setting allows the DMX transmission speed to be slowed downbecause certain Dimmers and Fixtures cannot respond to full speed DMXThis slightly diminishes the performance of the desk, but will avoid lowspecification devices missing DMX instructions. The larger the value of X,the slower the desk response will be.If the express is only outputing 125ch of data the refresh rate could be quite high, causing the alpha packs to skip about during slow fades. They would remain fairly constant when on a set level. Link to comment Share on other sites More sharing options...
ryandell Posted October 14, 2007 Share Posted October 14, 2007 Hello, When we did a show whereby we put 7 Mac 300's through the DMX chain with Four Betapack 1's, One Beta pack 2 and 3, the flickering occured on the Betapack 1's, When we plugged the mac's into the desk directly the flickering went away, so we put it down to putting to much info through the Demux. I know somebody said have you plugged the Pack directly in the desk, this might help to find the fault. Hope this might help Cheers Ryan Link to comment Share on other sites More sharing options...
neilalexrose Posted October 14, 2007 Share Posted October 14, 2007 Following on from James Remo - to change the transmission speed of the desk press: SETUP, OUTPUT CONFIGURATION (OPTION 2), then DMX SPEED (Softkey S4) and set the speed, fast, medium or slow. The only other thing I would suggest is termination. Put the alpha packs on the other universe (following the key presses above will also take you to the universe start address option. start universe 2 at DMX 1 which will give you a double of the first, and shouldn't involve any repatching) and plug in the alpa pack with a terminator on the output. (5 pin XLR with a 120ohm resistor wired across pins 2 & 3) Again, there are numerous topics regarding termination and fluctuating DMX outputs. I would also, if possible, put the address of the alphapack higher than the demux unit's highest address. Just in case its a conflicting address issue and the demux doesn't like it! (it shouldn't be, but anythings worth a try!) I had a similar problem when I tried to use an older Arri sub unit with a DMX thru (desk ran through the unit to the dimmers). Whenever I put an output up on the desk going through the sub unit, the output on the dimmers would flicker, however when the recorded sub was put up from the ARRI unit the output was fine. I never solved the problem, and it never occurred to me to try the DMX speed, but I may suggest it to the next person to try it. Neil Link to comment Share on other sites More sharing options...
Stutwo Posted October 14, 2007 Author Share Posted October 14, 2007 Thanks for the replies, will try out the suggestions and report back tomorrow. Link to comment Share on other sites More sharing options...
danjshelton Posted October 14, 2007 Share Posted October 14, 2007 As James said, the speed of the DMX refresh rate needs to be slowed down, this is definatly the case on the Pearl. When a company I work for occasionally had problems we found the fastest rate that could be used was 161ms, this speed let the alphapacks work perfectly fine and fade properly. Try this speed on the ETC and hopefully it will work! Cheers Dan Link to comment Share on other sites More sharing options...
KevinE Posted October 14, 2007 Share Posted October 14, 2007 I've seen this before as well. Some fast desks can develop noisy faders which a fast dimmer pack will show, but be masked by slower ones etc and all other combinations.. You get it with moving heads sometimes, they can 'judder' on slow movements due to refresh vs fade time conflicts. Link to comment Share on other sites More sharing options...
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