Vin Trouble Posted December 12, 2011 Author Share Posted December 12, 2011 Hi Peter, One of the backdrop and controller is one month old, and the replacement 9Q8 is a week old, so not PAT tested yet. These show up the same fault as the other stuff. I'm also using a foot controller and a laptop (or PC), and 2 leads - that's it - nothing else. I've tried different leads and made sure they are proper DMX spec. If I can get a hold of a cheap DMX desk I can eliminate the floor pedal as the bad guy. Link to comment Share on other sites More sharing options...
pmiller056 Posted December 13, 2011 Share Posted December 13, 2011 The fault symptoms you describe (something cooking that should not be and getting hotter as the brightness is turned up) where the only physical links between the equipment causing issues are the DMX cabling and the power cabling would strongly suggest faulty insulation somewhere between the power and the DMX side, hence the suggestion for PAT testing. I'm not trying to belittle your knowledge or abilities, I would be very, very careful about using any of the equipment with the faults you describe until you have *all* of the equipment involved checked out - if there are insulation faults then any of the interconnected equipment may become live in unexpected ways which could hurt someone badly. Regards, Peter Link to comment Share on other sites More sharing options...
timsabre Posted December 13, 2011 Share Posted December 13, 2011 I'm not trying to belittle your knowledge or abilities, I would be very, very careful about using any of the equipment with the faults you describe until you have *all* of the equipment involved checked out - if there are insulation faults then any of the interconnected equipment may become live in unexpected ways which could hurt someone badly. It's extremely unlikely to be live, more smoke would already have escaped if it was mains live.It sounds more like the LED drive voltage is shorted to DMX ground somewhere. Link to comment Share on other sites More sharing options...
pmiller056 Posted December 13, 2011 Share Posted December 13, 2011 Fair comment. Regards, Peter. Link to comment Share on other sites More sharing options...
Don Allen Posted December 13, 2011 Share Posted December 13, 2011 It could be a wiring fault in the led starcloth. Do you know anyone with a regulated power supply that has an adjustable current limit. If so, set the power supply to the led starcloth supply voltage, is it 12V?, then set the current output to the lowest setting, the output voltage will stay at 12V. Then connect the led starcloth, the output voltage will drop to 0V, then increase the current control. Initially the voltage will drop to 0V as the power supply cannot supply enough current for normal operation. Watch the power supply meters as the current increases. If the led starcloth is ok, the current will level off and the output voltage will rise to 12V. If the starcloth wiring is faulty, the current will continue to increase as you increase the current control, but the voltage will not get to 12V. Do not increase the current above the rated current of the led starcloth. If it only has voltage and wattage, divide the wattage by the voltage to get the current consumption. Link to comment Share on other sites More sharing options...
DrV Posted December 13, 2011 Share Posted December 13, 2011 It's extremely unlikely to be live, more smoke would already have escaped if it was mains live.It sounds more like the LED drive voltage is shorted to DMX ground somewhere. I'm sure I've heard of that before... Oh yes - there it is in post #13 ;) Link to comment Share on other sites More sharing options...
Vin Trouble Posted December 13, 2011 Author Share Posted December 13, 2011 The thing is I've 2 backdrops, 2 controllers for the backdrops, and 2 9Q8's, and I get the same fault with any combination. I would expect different results unless both backdrop controllers or both 9Q8's were faulty, no? Link to comment Share on other sites More sharing options...
timsabre Posted December 13, 2011 Share Posted December 13, 2011 The thing is I've 2 backdrops, 2 controllers for the backdrops, and 2 9Q8's, and I get the same fault with any combination. I would expect different results unless both backdrop controllers or both 9Q8's were faulty, no? You have probably got 2 faults as well. Finding two faults is sometimes very difficult. Link to comment Share on other sites More sharing options...
Vin Trouble Posted December 13, 2011 Author Share Posted December 13, 2011 The thing is I've 2 backdrops, 2 controllers for the backdrops, and 2 9Q8's, and I get the same fault with any combination. I would expect different results unless both backdrop controllers or both 9Q8's were faulty, no? You have probably got 2 faults as well. Finding two faults is sometimes very difficult. Twice as difficult? Used the backdrops with generic 3x36w parcans no probs, Martin Pro 400's etc, got 9Q8 and nearly fried either of the b/d controllers, rerurned 9Q8 and using the replacement gets same result?? I suppose it's possible that both 9Q8's are faulty? Quick question - are all PAT testers basically the same? Or are there guys specific to lights/live music etc? Link to comment Share on other sites More sharing options...
timsabre Posted December 13, 2011 Share Posted December 13, 2011 You have probably got 2 faults as well. Finding two faults is sometimes very difficult.Twice as difficult? The old saying goes that finding 2 faults requires 4 times the intelligence. I would say both 9Q8's have a fault where the LED array is shorted to the chassis somewhere. This is putting a voltage on the DMX ground which is causing your smoking resistor.It's not so unusual to have a repeating fault like this on a manufactured product, maybe a pad too close to a mounting pillar or something like that. A pat tester will not help you here. Link to comment Share on other sites More sharing options...
Vin Trouble Posted December 14, 2011 Author Share Posted December 14, 2011 Cheers, Timsabre and everyone else for the replies. I'll get this stuff tested and let you know the (hopefully good) outcome. Link to comment Share on other sites More sharing options...
Brian Posted December 14, 2011 Share Posted December 14, 2011 Quick question - are all PAT testers basically the same?Yes, most of them are completely useless, holding a paper qualification which isn't worth the paper it's printed on. There, I said it. And I hold the said qualification, but at least I understand the underlying theory and practice. You don't want a PAT tester; you want a good electronics engineer who knows their onions (aka DMX). There are a number of people on here who fit that description. Whereabouts are you? Link to comment Share on other sites More sharing options...
Vin Trouble Posted December 14, 2011 Author Share Posted December 14, 2011 Hi Brian, Up in the Frozen North - Glasgow. Link to comment Share on other sites More sharing options...
pmiller056 Posted December 15, 2011 Share Posted December 15, 2011 As a stop gap, can you find/borrow another DMX controller so that you can operate your equipment as 2 electrically independent setups until you get your problems sorted? Regards, Peter. Link to comment Share on other sites More sharing options...
Vin Trouble Posted December 15, 2011 Author Share Posted December 15, 2011 Hi Peter, It's an option, but I've a mate who drums for Twin Atlantic - he's gonna have a word with his lighting guy and hopefully help me out. Cheers for the idea, though. Link to comment Share on other sites More sharing options...
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