Jan 26, 2008 10:04 pm Quote:
My -17 went out two years ago and then again twice in the past week. Searching the net a little it has since become a fairly well know problem.
Why... I had no idea you had a daughter :)
It's official Behringer MX9000 has a fatal flaw
Posted on Jan 26, 2008 09:27 pm
Walt
Chief Cook and Bottle Washer
Member Since: May 10, 2002
This could have been validated in my absence, but just in case, it's official the + and - 17V regulators in the power supply of the MX9000 are under rated. My -17 went out two years ago and then again twice in the past week. Searching the net a little it has since become a fairly well know problem. For those who have them invest in a couple of LM338T 5 Amp regs to replace the LM350T 3 Amp regs. It is a 'plug and play' or drop in replacement. The cost through digi-key is about bucks 10 delivered.
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Jan 26, 2008 10:04 pm Quote:
My -17 went out two years ago and then again twice in the past week. Searching the net a little it has since become a fairly well know problem.
Why... I had no idea you had a daughter :)
Jan 26, 2008 10:12 pm Aaaaahahaaa!
<< pencils in a smartass point for zek
Jan 27, 2008 01:49 am Hahahaha
Sounds like they tried to cut costs copying that mackie schematic.
Jan 27, 2008 08:59 am Two of em there Zek, Although it would be my grand-daughter that would be closer to the age of 'goin out'. (I hope I didn't transgress some new millenium term and make her and I sound really bad)
Ya Colonel, I could think of a lot of ways they could have done it. Blind copy of Mackie, poor or no worst out cast study, at load componant selection to meet cost constraints. I called tec support and they are not even allowed to get near a schematic. Behringer uses the 'qualified service center' concept for repairs. That was scarry. The center close enough to me to be realistic "ho-joes-we-fix-it" answered the phone like the out end of a six day drunk. The guy thought an MX9000 was an amplifier. I was seriously thinking about having a good tech give it a once over, but after that I decided I would fix it myself.
Jan 27, 2008 08:30 pm That is really odd. As you know my desk has the same power supply. My 24 x 4 never had an issue and now my 32 x 8 has not had it either. (knocks on wood)
I am wondering if the amp draw is that much larger for the MX9000 then it is for the MX3282A as they appear to be the exact same 150watt PSU.
Although mine is racked with good cooling so that might help as well.
I may just go and order a pair from Digikey just for the sake of saying I am safe in case of sudden regulator death.
Anyway, thanx muchly for the heads up Walt.
Jan 28, 2008 09:15 am I have no idea Noize. I went to school in electronics with Moses, and haven't really worked it for decades. Beyond that I have no idea how one would get any real technical data on the board. The last time it went belly-up it was basicly in a quiesent state. I was taking about a half hour ear break when I heard the monitors 'pop' in the other room. I'm going primarily on intuition at this point. The net is filling up with reports. The unit was not that hot either this last go-around. I'm tempted to pop the top on the board itself, but I doubt I will find any smoking gun. I'm real leary about entrusting the unit to the service people I spoke to on the phone. Behringer seems to be very tight lipped about the whole thing. The point that grates my butt is that the layout of the board is sooooooo great for recording with the 24 direct outs and 24 return channels. Perfect match to my HD24. I can live with the un-sealed pots, mediocure pre-amps, etc. I'm not running a porta-studio for MGM. We'll see. I'll do a little more poking around, and maybe I'll pop the top if for nothing else just to give it a thorough vacuume. For now it's not a huge problem. I've got no percussion sessions schedlued and I going directly in and out of a Delta 1010 using Cubase control room for all of the switching, volume, etc. I've got enough di-boxes / tube amps to cover a few inputs at a time.
Jan 28, 2008 06:43 pm Ya, like I said. I may just order a pair to have on hand just in case then. Funny that it is just coming to a head now though. I'd have to look but I'm guessing mine has got to be at least 5 years old by now. I traded the 2442 for the 3282 maybe 3 years ago, or close to it and I'm sure this one was used. But since the rack was so hard to get into at the time I just left him the PSU that was with the 3282 and kept mine from the 2442 in the rack.
So maybe its possible that it might have been using different regs at the time. Either way, I'm not taking any chances.
Jan 29, 2008 02:57 pm Hi there, i'm new to this forum but came across it as i have had the same problem with my mx9000.
I just wanted a little advice on repairing it, i ordered up a bunch LM338t's (a few extra spare), do i replace all marked LM350's as some are not marked with that number? or just replace every regulator?? i am not an electronics wizz (i don't know alot of real technical stuff) but i am very good with this kind of thing (soldering etc) having replaced parts and repaired turntables, mixers and old synths in the past.
i just need to know exactly which parts to replace or do i just replace them all ie: first & third regulator from the right, type of explanation. if any one could help me out it would be greatly appreciated.
many thanks
Jan 29, 2008 05:32 pm The most important to replace are the two LM350's that supply the +- 17 volts. Those circuits are marked on the circuit board with +17 and -17 respectively. You might also want to smear a little heat transfer goop under them like used for a cpu on a puter on the heat sink. I am not challanging your technical expertise, but use care to note how the washers and bolts are used to secure the regulators and ensure that they are replaced exactly as removed. I'm gonna write Behringer and see if they have anything more to say about this. I doubt they will, but one never knows. Their standard tech folks are well....... not aware.
Jan 29, 2008 05:49 pm Yikes, What a dummy I am! While looking for a serial number for the question subimtted to Behringer, I noticed the power supply case states + and - 17 volts @ 3.5 A output. Blahahahahahahaha! With 3A regulators. Now that is a blinding glimps of the blatently obvious!
Jan 29, 2008 08:26 pm That just might explain some things. An under rated reg in the board.
But I am guessing that the full load will not be realized until the desk is under full load, such as almost every channel and its pre's being used, plus phantom running.
Jan 30, 2008 07:59 am thanks alot for the help, will let you know how it goes.
good luck with getting any info out of behringer on this one, in my opinion this fault is so widely reported that they are obliged to compensate customers who have experienced his fault. i do not over use and abuse my mx9000 as i only have small home studio setup. i had an mx2442 for about 6 years and it never gave me a problem.
Jan 30, 2008 09:00 am Yup MRB, and I'll bet Behringer knows of the situation. If this problem and like problems ever impact sales, then maybe there will be some compensation made. Until then, I highly doubt you'll see anything. I have no idea what current units are shipping with. It would be interesting to see if the componants have been changed in new units. I will say this; Behringer is in stark oposition to Alesis for one. I had trouble with an Alesis HD24 and the tech support people were elbows over ******** to get it resolved. My problem was hardware and first call in the problem was pushed up internaly to a supervisor. The failure occured a few months after warrenty expired, but the supervisor waved the warrenty restriction. I'll have to paraphrase as it has been awhile, but his comment to me was basicaly 'I have that unit myself and it is a well made unit. It should not have failed'. At his insistance not mine the unit was picked up, repaired, and returned in less than a week at zero cost to me. With that I received a detailed description of the failure mode and repair process which was also fully warrentied. No need to excersize that warrenty, it has been a rock ever since.
Feb 07, 2008 09:22 pm Just in case anyone is interested; I put the LM338T rectifiers over the weekend and the board is up again. No smoke or odd smells rithing from within. So I guess they didn't hurt anything. Who knows how long it will stay up. Time will tell.
Feb 08, 2008 09:40 pm Make sure and keep us posted as to if it fails. Which I am sure it won't. That appears to be the cure from everything I have read. And funny enough, or may be not really funny. But interestingly it seems it is only happening when the PSU is used on the MX9000. I have checked and all the desk's including the MX 2442A, MX 3282A and the MX 9000 all use the same PSU.
Feb 09, 2008 08:20 pm Obviously I don't have a schematic; they're coveted more closely than area 51 documents, or Hillarys waist size, (either would cause public panic) but I suspect the MX9k has the greatest draw, if for no other reason the meter bridge. But I'm with you. I don't consider it fixed until some time down the road. Could be natural componant tolorance drift that pushed it over the edge or it could be some other more hidden fatal flaw, but one thing is becoming obvious, it is enharent to the beast.
Jul 15, 2009 10:33 am Hi everyone...need your help. My power supply now turns on but no out-put. First it started to behave erratically. I checked the inside and all appeared perfect. Unfortunately, when checking the fuse, silly me must have flipped the fuse to 110V instead of 220V. It immediately turned off after a brief run. I have replaced the blown fuse and all i get is the red switch turning on. No
Aug 19, 2009 07:50 pm Well, I suggest you go back in this thread and either replace the reg's as stated or bring it into a qualified shop. It does indeed sound like you smoked the output section of the PSU.
Oct 20, 2009 06:46 am Well, I did a major overhaul on my MX8000A PSU 5 years ago after it failed for the second time with the -17V problem (first time I just used LM350T's again not realising they were underated for the job).
I replaced with LM338T's, used computer quality heat transfer compound, and also decided to upgrade all the electrolytic capacitors to high working temperature versions.
Despite this the same problem is beginning to raise it's ugly head again, and of course I have a whole load of important work I need to get done in the studio !
I think part of the problem is that there is not enough airflow inside the PSU case and the -17V voltage reg. runs at too high a temperature shortening it's life eventually resulting in failure.
I'm going to look at a better fan more ventilation holes in the case, and possibly a seperate heatsink for the -17V reg.
I'd rather be making music, but finances dictate I have to fix this problem, a new mixer is not an option at the moment, and besides i'm happy with the MX8000A mixer itself, it's just the PSU which sucks !
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