Munro Posted June 17, 2011 Share Posted June 17, 2011 Hi guys, heres an interesting one. I'm out of ideas, as are Zero 88, so lets see if anyone on here has any suggestions. I currently have a Zero 88 FatFrog running 36 channels of Betapack 2. My DMX chain goes as follows: FatFrog > Dimmer 1 > Dimmer 2 > Dimmer 3 > Dimmer 4 > Dimmer 5 > Dimmer 6 > *5-3 pin convertor* > Architectural LED 1 > Architectural LED 2 > Architectural LED 3 > Architectural LED 4. Everything works fine, except Dimmer 2. The other dimmers all have the green "OK" light on for DMX, and they respond to the desk, as do the LEDs. Everything after Dimmer 2 works, everything before it (Dimmer 1) works. It just WILL NOT respond to the desk, yet the flash buttons function perfectly. Which made me thing it were a DMX issue. If I unplug the "output" DMX cable, magically, it starts to repond and work again, as though there were nothing wrong (with just Dimmer 1 and Dimmer 2 in the chain). I've tried different cables, I've been introducing devices after it, one at a time, putting it first in the chain... It just refuses to work. I've admitted defeat for the time being and hired in a beta 1 (all I could get my hands on), although for the future, I'd like to know whats wrong. The best conclusion Zero88 can come up with is a faulty DMX Driver, although before I just bite the bullet and get finance to order me one, I'd like to do a bit more digging. Any thoughts and suggestions welcome. Ta,JM Link to comment Share on other sites More sharing options...
fireball40k Posted June 17, 2011 Share Posted June 17, 2011 A silly question, but is the chain properly terminated? It sounds like there might be some odd reflections coming back down the line and that this unit is particularly sensitive to it. Also, have you driven it with a different desk in case there's something about the DMX output of the frog (possibly the frame rate) that's upsetting it? Link to comment Share on other sites More sharing options...
Munro Posted June 17, 2011 Author Share Posted June 17, 2011 Thanks for your reply. I'm told the dimmers terminate themselves... correct? (as for the LEDs, I think so... but I've never had a problem with them before, and it did the same when there were just four dimmers after it, and the LEDs removed completely.) The lighting desk was installed with these Dimmers and has worked for many years (so I'm told). (also, I don't have another desk readily available to test with :/) Link to comment Share on other sites More sharing options...
fireball40k Posted June 17, 2011 Share Posted June 17, 2011 As far as I know, Betapack 2s do not terminate themselves. This might be where your problem lies although I'd be surprised to get this problem with so few devices on the line. Link to comment Share on other sites More sharing options...
IRW Posted June 17, 2011 Share Posted June 17, 2011 As far as I know, Betapack 2s do not terminate themselves. This might be where your problem lies although I'd be surprised to get this problem with so few devices on the line. But the Betapacks are not the last fixture in the chain, Do the architectural LED's self-terminate is what you should be looking into! Link to comment Share on other sites More sharing options...
pritch Posted June 17, 2011 Share Posted June 17, 2011 Betapack 2s do have internal termination, but it's not automatic - you have to select it by adding a wire link. Certainly worth checking. Manual will be on the Zero88 website, and I'm sure that'll have details of what to check. Link to comment Share on other sites More sharing options...
boatman Posted June 17, 2011 Share Posted June 17, 2011 ..If I unplug the "output" DMX cable, magically, it starts to repond and work again, as though there were nothing wrong (with just Dimmer 1 and Dimmer 2 in the chain)... Does this mean you are unterminating Dimmer 1 & Dimmer 2 when it works? If so try putting the termination back. If it stops working again it probably means that the DMX signal between the XLRs and the receiver chip on the PCB has gone one-legged. RS485 receiver chips will often work on a one-legged signal if the amplitude is sufficiently high as you get with an unterminated signal, but fail if the signal is terminated. Hope that helps. Link to comment Share on other sites More sharing options...
jonhole Posted June 17, 2011 Share Posted June 17, 2011 I'm out of ideas, as are Zero 88 Hi Joe, Who have you been talking to here at Zero 88? Have we had the Beta Pack in to look at? Cheers Link to comment Share on other sites More sharing options...
Munro Posted June 17, 2011 Author Share Posted June 17, 2011 I'm out of ideas, as are Zero 88 Hi Joe, Who have you been talking to here at Zero 88? Have we had the Beta Pack in to look at? Cheers Hi Jon. I've been speaking to Keith Rogers. The Betapack is still firmly stuck to my wall, as I was in need of a quick fix! (show on Monday!) The only thing Keith could suggest was the DMX driver, however my local supplier didn't have one in stock (Nstage). Before I go off and get them to order me one, I was just looking to see if anyone else had any ideas. Thanks.JM Link to comment Share on other sites More sharing options...
pritch Posted June 17, 2011 Share Posted June 17, 2011 Did he suggest a particular chip? If so, then you might have more luck with your local branch of RS. They should be open tomorrow morning. Link to comment Share on other sites More sharing options...
Munro Posted June 17, 2011 Author Share Posted June 17, 2011 It isn't urgent anymore, as I've managed to get my hands on a beta 1. Link to comment Share on other sites More sharing options...
Brian Posted June 18, 2011 Share Posted June 18, 2011 Plug it up as you want it to run and put your multimeter, set to Ohms, across pins 2 and 3 at the desk end with the desk unplugged. If all is as it should be, termination wise, you will measure between 100 and 120 Ohms. If you something something closer to 50-60 Ohms it's double terminated somewhere. Maybe one of the packs has had it's internal link made. Link to comment Share on other sites More sharing options...
DrV Posted June 18, 2011 Share Posted June 18, 2011 Plug it up as you want it to run and put your multimeter, set to Ohms, across pins 2 and 3 at the desk end with the desk unplugged. If all is as it should be, termination wise, you will measure between 100 and 120 Ohms. If you something something closer to 50-60 Ohms it's double terminated somewhere. Maybe one of the packs has had it's internal link made. This test will need to be done with everything powered off as the meter reading will likely get messed up by current flowing into the various receivers in the chain. I suspect that boatman has got it right - the connection between the PCB and the XLRs is made by individual wires which are paired up (input and output) into terminal blocks - might even be as simple as a loose scew. Dave Link to comment Share on other sites More sharing options...
Brian Posted June 18, 2011 Share Posted June 18, 2011 This test will need to be done with everything powered off as the meter reading will likely get messed up by current flowing into the various receivers in the chain.Not really necessary. The input impedance of the receivers is around 12k. Link to comment Share on other sites More sharing options...
DrV Posted June 18, 2011 Share Posted June 18, 2011 This test will need to be done with everything powered off as the meter reading will likely get messed up by current flowing into the various receivers in the chain.Not really necessary. The input impedance of the receivers is around 12k.It's not the impedance of the receivers that causes the problem, it's the fact that they're powered up. Using a DVM I have found that I get all sorts of odd readings (including -ve ohms!) due to the fact that the 12k, or whatever it is, is not 12k to 0v but 12k to say +5v. You might find that using a conventional MC meter (like an AVO) would be less affected due to the higher current it uses for testing resistance. Not "having a go" by the way, just explaining why I think it should all be powered off for truly meaingful readings CheersDave Link to comment Share on other sites More sharing options...
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