Ben Lawrance Posted February 28, 2004 Share Posted February 28, 2004 Hi all, We've just had a new install done at my school (I'm staff, not pupil) Included in the install (fully spec'd by me) I got a Z88 Alcora. I did my research, and for the budget we had, it seemed the right desk for the job. Now, it has been used for 5 shows now (within the last 4 months) and I am finding the faders to be even more annoying the more I use it. When I move (say the master) fader, it will do absolutly nothing untill about 60%. So when I continue to move the fader up to say 80% the lanterns will be on about half. The last 20% will be very "quick" to fade up. Am I making any sense what so ever? Is this a fault with the desk? Is it ment to do that? Maybe a reply from one of the Zero lads would set my mind at ease. CheersBen Lawrance Link to comment Share on other sites More sharing options...
Bryson Posted February 28, 2004 Share Posted February 28, 2004 It sounds more likely that the problem is the dimmers and possibly the "law" that they're set to. What are they? Have you tried a different desk? (I'm aware this may not be possible.) Link to comment Share on other sites More sharing options...
jagardner1984 Posted February 28, 2004 Share Posted February 28, 2004 Is it not to do with the trigger level the dimmers and the desk are set at. For example, only when the desk or the dimmer receives a certain percent will it do anything at all. If this has been incorrectly set during the install - then surely you can get whoever installed it back in to fix it. James Link to comment Share on other sites More sharing options...
Ben Lawrance Posted February 28, 2004 Author Share Posted February 28, 2004 I did think about that. I have used my LanBox (computer controlled), and XLS with the dimmers (Beta 2's) and they work A ok. No problems. RgdsBen Link to comment Share on other sites More sharing options...
jagardner1984 Posted February 28, 2004 Share Posted February 28, 2004 OK, it can't be the dimmers, at least I don't think so. Presumably you have awarranty, so if it is still quite new, get the company in. Percentage Values are there for a reason, the light output at 20% should be proportionally 1/5th of the full beam - or is that wrong. The product is in effect faulty if it is providing so little functionality James Link to comment Share on other sites More sharing options...
Stu Posted February 28, 2004 Share Posted February 28, 2004 Percentage Values are there for a reason, the light output at 20% should be proportionally 1/5th of the full beam - or is that wrong.Well if your using old dimmers that might have seen better days, the curves could be different for each dimmer you use in a rack, and therefore 50% on one might be different to the 50% on another... Ah the memories of 3 racks of JTMs and STMs at school :D Stu Link to comment Share on other sites More sharing options...
Brian Posted February 28, 2004 Share Posted February 28, 2004 I had a similar problem with Beta 2s controlled by a frog which turned out to be the blackheat control on the dimmers. Link to comment Share on other sites More sharing options...
andystone Posted February 28, 2004 Share Posted February 28, 2004 Somewhere along the line you need to have a square law in the control side, usually this is in the dimmers and it overcomes the problem that when you start fading up a channel the lamp has to warm up, so it distorts the fade to put more level into the dimmers at the bottom end to get the lamp going and then the opposite at the top end. However, this doesn't sound like the problem if you have a tried another Z88 desk and it works OK, sounds like faulty kit! In any case you shouldn't be wasting your time on it, if it's a new install and it ain't working right, get the install company back in to sort it out! AndyStagetec Link to comment Share on other sites More sharing options...
Mars Posted February 29, 2004 Share Posted February 29, 2004 Older dimmers (e.g. ABD) have a current input instead of a voltage input. As a result, when driving these dimmers with a voltage, the dimmer suddenly 'opens up' on a certain level, mostly in the range of 50 - 80 %, depending on the drive circuit (actually, the output impedance of ...).This feature is distinguishable by following the input line to a (possible) opamp. If it is a 8 pin case, the current input is on pin 2 (minus or summing node). If you're not sure, post the brand/type here, and I will try to get the circuit to clearify. The conversion is simple: add a 27k resistor in series with the current input. The 0-10V will be converted to the proper current values. You can place the resistors in the dimmer, on a separate input plug and connect them to the normal (current) input plug. Check the circuit before making modifications! Observe safety issues! Link to comment Share on other sites More sharing options...
Potassium Neuf Posted March 1, 2004 Share Posted March 1, 2004 Have you tried connecting a DMX Debug or similar piece of DMX monitoring/display equipment to the DMX outputs of the desk ? If the DMX outputs match what you would expect from the position of the faders, then the problem lies elsewhere in your rig, as suggested by others above :D Link to comment Share on other sites More sharing options...
Mars Posted March 1, 2004 Share Posted March 1, 2004 My former post was mostly triggered by the symptoms: nothing from 60% and then nervously quick.But rereading the topic, you mentioned there was no problem when using a (Zero88) XLS. Just from my own experience, I would inspect visually the interiors of the Alcora for loosy connectors, especially ground connections. But if all seems ok, visit your distributor for a cross-check and/or replacement.By the way, do you use the same or different cables between the desks (Alcora & XLS). If different, also check the ground connections of the Alcora cables. Or exchange them. Link to comment Share on other sites More sharing options...
Eric Posted March 1, 2004 Share Posted March 1, 2004 Dear Ben, I can not think of anything obvious that would cause this with this desk.The easiest thing may be to give me a call on 01633 838088 if you can get the desk in front of you and I can talk you through some tests. Link to comment Share on other sites More sharing options...
themadhippy Posted March 1, 2004 Share Posted March 1, 2004 can individual channels of the alcoa be given special attributes? maybe one has been applied globaly Link to comment Share on other sites More sharing options...
Pardisaster Posted March 1, 2004 Share Posted March 1, 2004 hmmm, ive used the alcora regually, with four or five types of dimmer, and we've never had that problem with ours. Never make the mistake I did and try and live edit in the middle of a performance.... *reminses of the amazingness of the Sirius.... from gods head to the techs hands...* Link to comment Share on other sites More sharing options...
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