willpower Posted August 19, 2008 Share Posted August 19, 2008 Hi All, I'm currently being the technical support for a week long conference, and am having huge difficulties with a mixer that is doing what I can only describe as crashing. I'm using a Behringer MX8000A, and at any random time, it will bang very loudly, and every light on the mixer will come on. The only way to sort it out is to switch off both speakers (using active Mackie SRM450s, so have to go to the speakers to switch them off - not good in the middle of a session), then turn off the mixer, and wait a good deal of time (a good hour) before using it again. Last night, this happened mid session. I'm on a Quaker course, and it was the quiet time of worship at the end of the day - we needed the sound system to play some music part of the way through. Towards the end, the mixer 'crashed', went bang, which shook up the meeting somewhat. I was completely stuck as to what to do, if I got up to turn the speakers off then it would disturb the entire meeting. So I stayed where I was and hoped the mixer wouldnt do anything. Unfortunately, it erupted into unbelievable loud bangs, which sounded like machine gun fire. I of course lept to the off switch, which sorted it out in the short term. It doesnt make any difference if there is any input into the mixer, whether it has signals going through it, or whether it is just on. Has anyone come accross this problem? Do you have any suggestions as to how I can sort it out? I have a spare mixer, as I'm running 2 sound systems in 2 different locations - so have swapped them over for the time being, but tomorrow I will need both at the same time, and dont want the behringer crashing halfway through! Many thanks in advance, Will Link to comment Share on other sites More sharing options...
Andrew C Posted August 19, 2008 Share Posted August 19, 2008 My first guess (only that without diagnostics) is the power supply or connections to it. I'd change the mixer ASAP; it isn't going to get better. Hire one if you have to, you could trash your speakers if you carry on! Link to comment Share on other sites More sharing options...
Sound In Gloucestershire Posted August 19, 2008 Share Posted August 19, 2008 hire another mixer ASAP, sounds like a power fault somewhere by the way, as for emergencies, you dont need to switch off the mackies, merely turn the master to Zero on the desk and unplug the XLR's, shouldnt cause any bangs. When you are happy the desk is ok again, plug the XLR's back in and turn master fader back up Link to comment Share on other sites More sharing options...
Rob_Beech Posted August 19, 2008 Share Posted August 19, 2008 Agreed, PSU seems like a good place to start. They're far from the best desks in the world, you might be able to pick one up used with PSU for not alot so it might work out ok. Failing that hire until you can get it fixed, don't risk losing more show time and as Andrew says, don't risk the rest of the system. Link to comment Share on other sites More sharing options...
KevinE Posted August 19, 2008 Share Posted August 19, 2008 I seem to remember a similar fault on one of these a few years ago, they have a seperate linear rackmount psu and the smoothing capacitors can shear off their legs right near the board. Link to comment Share on other sites More sharing options...
Killyp Posted August 21, 2008 Share Posted August 21, 2008 Are you sure it's the mixer and not the speakers? I know they wouldn't both do it at the same time, but are they both running off the same power socket when you do this? A friend told me about a position he was in when he had a system doing exactly the same as this. Turned out it was the mains plug he'd wired which was powering the amp rack. The cables had been screwed in inside the plug, and heated up as they carried a larger current, causing the screws to be pushed out of the way very slowly over several months. Just as the cables reached 'breaking' point, the power would cut out for a fraction of a second as the cable moved just a fraction inside the plug - enough to cause a bang. One possibility, but it sounds as though it's a problem with the mixer power supply... Link to comment Share on other sites More sharing options...
Mr.Si Posted August 21, 2008 Share Posted August 21, 2008 Had the same issue with my MX9000 when I had it (I bought it because I learnt live sound on an 8000A and liked the layout). PSU overheating problem is what it was. I opened up the PSU and it turned out only one of the two fan cables were connected to the power! However, it still didn't solve the problem. Bizarrely, this only happened in one venue, unless I took a portable fan and aimed it at the badly designed (horizontal layout) heatsinks on the back of the PSU. I agree with others, replace the desk with something else, like an Allen & Heath GL series! :P Maybe... Link to comment Share on other sites More sharing options...
parisonj Posted August 21, 2008 Share Posted August 21, 2008 Hi, this is the PSU failing. It has happened to me a couple of times, and I have remedied the situation on my MX8000. Technically, what is happening is that the +18/-18V voltage regulators in the supply are failing because of overload. This overload is not your fault, the chips used are effectively underpowered for the desk. There are higher powered replacements available, but what I have done so far is replace with the same types, but beef up the cooling system in the PSU by adding some more fans in strategic places.The higher-powered types are pin-for-pin compatible. If you don't want to do it yourself, then a recognised service centre for Behringer should certainly be aware of the problem, and be able to sort it. Hope this helps,Jason Link to comment Share on other sites More sharing options...
willpower Posted August 24, 2008 Author Share Posted August 24, 2008 Thanks so much guys. Am now back from the conference - found ways round it by only using one mixer for both locations and moving it between the two, and the evening where we needed both was a video night, so I used two DIs to take the signal from the laptop playing the DVD to the active Mackie's, and using the mixer with the passive speakers in the 2nd location. Killyp: I'm sure it's not the speakers as all of the lights on the mixer come on when it goes bang, and the speakers were plugged into separate sockets on opposite sides of the room. Mr.Si: As much as I would love an Allen & Heath GL series, having just spent £400 on this one (perhaps a little too much, all things considered), I don't think I can at the moment... parisonj: Thankyou, that's great. I wont be doing it myself, as my knowledge of mixer power supplies is limited! I will certainly get in touch with a behringer service centre, and see what they can do. Any suggestions for good ones near London? Many thanks for all the comments, Will Link to comment Share on other sites More sharing options...
tolley1466 Posted August 24, 2008 Share Posted August 24, 2008 Thats ace to see that you got around the problem! Quick decision making looks like your good at it!Well done =] Link to comment Share on other sites More sharing options...
KevinE Posted August 24, 2008 Share Posted August 24, 2008 the behringer service people (your end) are http://www.electronicmusicservices.co.uk tel (southend) 01702 613172 Link to comment Share on other sites More sharing options...
Russ83 Posted August 24, 2008 Share Posted August 24, 2008 There was a similar problem with the later DDX3216 desks that if I remember correctly was a combination of a motherboard and power supply fault. The solution was to pay another £100+ and send the desk off to the main repair shop in Germany, after that all problems were solved. Your local repair shop should hopefully be able to sort this for you. Link to comment Share on other sites More sharing options...
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