michael Posted July 6, 2015 Share Posted July 6, 2015 Good evening guys, At my venue we have a few cheap LED Stairville 252 battens that we have a problem with.. We recently had a band in that was using a £10 Chamsys dongle, no problem until the end of the evening where the LEDs stopped working and our dimmer wouldn't respond to DMX, not to much of an issue as the band had finished playing.Tonight we went to use our in-house Chamsys desk and none of the LEDs will work with DMX, its not an isolated issue and is the same problem across all 4 of them. I have taken them down and tried to operate them on their own with both the Chamsys desk and a small 6 channel Strand desk but none of them work.. Does anyone have any ideas? Could it have been caused by the dongle? Michael Link to comment Share on other sites More sharing options...
erik10_4 Posted July 6, 2015 Share Posted July 6, 2015 Good evening guys, At my venue we have a few cheap LED Stairville 252 battens that we have a problem with.. We recently had a band in that was using a £10 Chamsys dongle, no problem until the end of the evening where the LEDs stopped working and our dimmer wouldn't respond to DMX, not to much of an issue as the band had finished playing.Tonight we went to use our in-house Chamsys desk and none of the LEDs will work with DMX, its not an isolated issue and is the same problem across all 4 of them. I have taken them down and tried to operate them on their own with both the Chamsys desk and a small 6 channel Strand desk but none of them work.. Does anyone have any ideas? Could it have been caused by the dongle? Michael Assuming they are powering up....does the display confirm they are set in 'DMX mode' ? .... and are they correctly addressed? Link to comment Share on other sites More sharing options...
michael Posted July 6, 2015 Author Share Posted July 6, 2015 Sorry should have clarified, yes they power up and they are in DMX mode. They work fine in the audio mode but not DMX..Very strange that all 4 have the exact same fault Link to comment Share on other sites More sharing options...
Don Allen Posted July 7, 2015 Share Posted July 7, 2015 It is possible that all of the DMX input ic's have been damaged. For troubleshooting you need a reference point so do you have a fixture that works with your desk so you have a good DMX source. Do you have a DMX splitter so you can plug one of the lights into your desk, bypassing the cabling. Using a splitter reduces the risk of damage to the desk from your faulty fixtures. Use this to test your faulty fixtures at the desk, removing the possibility of a cabling fault. Can you plug your working fixture in at the end of the cabling to your faulty fixtures ? I have had to replace the desk DMX out ic and the fixtures DMX in ic's due to a surge. Good reason to use an opto isolated DMX splitter. Link to comment Share on other sites More sharing options...
Jivemaster Posted July 7, 2015 Share Posted July 7, 2015 Does anything work off your desk's DMX? Have you checked all the cables? One open or shorted cable will lose DMX for all units beyond it. Link to comment Share on other sites More sharing options...
michael Posted July 7, 2015 Author Share Posted July 7, 2015 I took all four units down and tried each one individually with several different DMX cables, I also made sure our small Strand desk worked by testing it with our dimmers.Unfortunately we dont have a DMX splitter so I'm not to keen to plug them into our Chamsys console! I think they may have had it! Link to comment Share on other sites More sharing options...
Geetrt Posted July 7, 2015 Share Posted July 7, 2015 I still think it's impossible to blow rs485 chips with only usb power. I think it's more likely one of the stairville units, or something else connected to mains, caused a power spike over the DMX line. Link to comment Share on other sites More sharing options...
timsabre Posted July 7, 2015 Share Posted July 7, 2015 I still think it's impossible to blow rs485 chips with only usb power. I think it's more likely one of the stairville units, or something else connected to mains, caused a power spike over the DMX line. The thing with USB is that the DMX ground gets a connection to mains earth (usually-some types of laptop aren't earthed). If there is some other fault causing floating voltages on the DMX line, this earth connection suddenly gives a fault current path which can blow things up. Replacing the RS485 chips is an easy fix if you can solder. If you're lucky they might even be socketed IC's. Link to comment Share on other sites More sharing options...
Don Allen Posted July 7, 2015 Share Posted July 7, 2015 If you are going to remove ic's from a pcb, cut the legs on the ic so you can remove the pins individually to prevent damage to the pcb, then fit a good quality ic socket to plug the replacement ic in to. If you use turned pin ic sockets, you will be able to fit a small cable tie underneath the ic socket to go around the top of the ic and hold it in place. Link to comment Share on other sites More sharing options...
michael Posted July 7, 2015 Author Share Posted July 7, 2015 Great advice, thank you guys! http://www.blue-room.org.uk/public/style_emoticons/default/smile.gifI'll open one up later and see if I can find the correct IC Michael Link to comment Share on other sites More sharing options...
Geetrt Posted July 7, 2015 Share Posted July 7, 2015 @timsabre: As you write: 'some other fault causing floating voltages ...' I was just addressing the question about the usb dongle CAUSING the failure. As is already said: it's always good practice to use an opto-isolated splitter. And I am still wondering why all four stairvilles blew, and the dongle and dimmers didn't.Are the Stairvilles on a separate mains circuit (fase)? If they are, what else is on that circuit? Maybe some heavy machinery? I've also seen one powersupply in one fixture to go bad, causing all fixtures on the DMX-line to blow their RS485 chip. So be carefull to check the powersupply. Link to comment Share on other sites More sharing options...
timsabre Posted July 7, 2015 Share Posted July 7, 2015 @timsabre: As you write: 'some other fault causing floating voltages ...'I was just addressing the question about the usb dongle CAUSING the failure. As is already said: it's always good practice to use an opto-isolated splitter. Yes, I wasn't disagreeing with you, I think there must have been an existing fault which was made worse by the earth on the USB dongle. So the fault was not really caused by the USB dongle, it just showed it up. Some devices have fault protection on the DMX circuits against overvoltage etc. I would guess the cheap Stairville devices did not and the other devices did. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.