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Anyone have a suggestion as to why all of a sudden my 14 month old M-Audio BX5a speaker would suddenly develop a hum and buzz? It's on only one speaker and it happens whether hooked up to a source or not, so it's definitely the speaker. It's coming from both the woofer and tweeter.
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I found this info that is useful
I think they had a bunch of bad caps that got installed on a bunch
of M Audios power amps
I copied and pasted the info for you in this post
If it is the power supply caps you have a very cheap fix
From someones post on your model
#
# Upon putting my ear to it, I realized that it was making a steady hum/buzz from both drivers. This was similar to a 60-cycle hum but a little raspy-er if that makes sense, and if I’m not out of my mind. Also it wasn’t a very loud hum. Only about as loud as you’d get from a bad cable or something.
# I tested for a bad input connection and tried using XLR instead of the 1/4 inch input. The problem was clearly inside the unit.
# I opened it up carefully, to see if there was anything obviously burnt or shorted or broken inside.
# After finding nothing that was obvious to me, I googled around and found a few posts on the m-audio forum talking about problems caused by worn-out capacitors. See: http://forums.m-audio.com/showthread.php?t=3871&page=1 and http://forums.m-audio.com/showthread.php?t=11926 and many others.
# One of my two main power-supply caps was indeed bloated. And I noticed some dark-brown crustiness on top of the other which I concluded might be leakage of “electrolyte,” whatever that is.
# I de-soldered and removed the old caps and set out to find replacements.
# I accidentally ordered 16V 6800mfd instead of 25V 6800mfd, which I didn’t notice until I had already soldered them in.
# I tried them anyway because in theory, since all the caps are supposed to do is smooth the supply current, too-low of a voltage rating on the cap would just mean that the caps will wear out sooner. The constant hum/buzz was gone with the new caps in. Instead what I got was a pop a few seconds after the unit was powered on. The pop is new. My functioning unit does not pop.
# I went and got the correct 25V 6800µF Capacitors and put them in but there was no change in the above behavior. Incidentally, I had to mount one on the bottom because the ones I got were more than twice as wide and a bit taller than the originals.
# I’ve double and triple-checked the soldering. I even opened up my functioning BX5 to make sure that the caps are in the right polarity.
# I tested for continuity between the capacitor leads and the destination/source on the printed circuit (for instance one path goes to what I believe is a Rectifier IC so I checked to makes sure that path was solid all the way from that component’s lead to the cap’s lead to rule out a bad solder joint… I did this for all the paths in the printed circuit)
# I’ve quadruple-checked for any visible shorts.
# I believe that my capacitor-replacement surgery was a success, so now I am beginning to doubt that bad caps were the real problem. It’s entirely possible that the buzz/hum I was hearing was there for some time since it wasn’t loud enough to hear until I put my ear right up to the unit. Maybe I have two problems, one of which I just fixed.
Power amp has a service issue
Could be something as simple as one of the RCA jack inputs is partially
shorting to ground
Service yourself or have it serviced
Did some checking and apparently these units break all the time... crap. Some have had luck replacing caPS.. I have to take it in or throw them away.
Check the power supply caps
Locate where the AC cord comes onto the printed circuit board
Check the larger caps near that
If you see leakage from one there is your culprit
Otherwise get the values of them and replace them
Check the solder connects on them as well
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