Hum coming right off the output of the board

[Anonymous067]

I have an old Mackie console, and one of the aux out jacks now has a hum coming off of it. It is not any inputs, the hum is there when the master out for that aux is muted (and just because, I also muted all the inputs...not like I needed to). Any thoughts, short of tearing the top off, for fixing this issue?

 

[rwhealey]

If we take your Mackie with a hum and my Mackie with a bad left output and put them together, we'd have a usable sound board!

It might not be worth fixing - most repair places around here charge $75 an hour and if it's a 1604 or the like, it's probably only worth $250.

 

[mbenonis]

Sounds like maybe a bad power supply/decoupling capacitor to me. Probably gonna have to pop the hood and replace the bad part...look for it in or around the output driver amplifier.

The good news is that if you can ID and replace the part, it's probably gonna cost you less than a dollar.

 

[CanYouHearMeNow]

If its not that, it could be that you just had a bad cable. You didn't really say any troubleshooting you tried.

 

[FMEng]

A hum could be caused by a ground loop in the cabling or equipment external to the console. If you move the plug from that auxiliary output to a different aux output, does it still hum? If yes, it's a cable or system problem, not the console. Do you hear the hum in the AFL for that bus? If yes, then it is a console problem.

 

[Anonymous067]

It's an SR56-8...10 years old.

I have noticed the PSU gives a nasty hum at times...more of a whirring noise I guess.
.).

 

[MarshallPope]

Have you tried unplugging everything else from the console to make sure there isn't some grounding weirdness or something coming in from elsewhere and for some odd reason deciding to manifest itself in this aux?

 

[waynehoskins]

It's a decade-old 8-bus. Could it be the ribbon cable problem? It's about the right vintage.

 

[bishopthomas]

It's humming because it doesn't know the words...

 

[TimmyP1955]

Pull the bottom panel, and break-n-make all the ribbon connections 3 or 4 times.

And look for bad solder joints on the aux's jack - it may have gone one legged.

 

[chausman]

It's I'm humming because it I doesn't don't know the words...

Just keep telling yourself that...
Joking!

And, as a solution, don't use that aux!

 

[Tex]

Just keep telling yourself that...
Joking!

And, as a solution, don't use that aux!

That's not a solution; that's a work around.

 

[museav]

According to the user manual, there is not much after the aux out mute, just the PFL/AFL split and the physical output connector. I personally would try some basic troubleshooting before opening up the console. Things like disconnecting whatever is connected to that aux, assessing whether the noise is in both the PFL and physical output for that aux, seeing what happens if you 'flip' the aux and subgroup controls, etc.

 

[DuckJordan]

Has the OP even told us what's being connected and what the boards setup is? I ask this because I just had to help a local high school tech run an area Mic through a board.

To me if its just a single aux causing hum its more likely to be an issue with the user and not the board.

Sent from my ADR6300 using Tapatalk

 

[chausman]

That's not a solution; that's a work around.

True, but if it started happening in the middle of a run, IMO, it's better to just work around a simple problem like this than try to fix it by taking the board apart or changing things.

 

[facethewolf]

If you have a powered speaker, hook it up to the aux out 3 feet from the board. Make sure it's plugged into the same circuit as the board. Make sure there is still hum in that condition. If so, then something may be shorted in the aux jack in the board.
If not then it's cabling or the amplifier.

Or you are set up in my home church--we have the most awful hums...and we live with it.

 

[Anonymous067]

Sigh.

I've been working on this stuff for over ten years. I wouldn't put this kind of thread up without "doing some basic trouble shooting".

It doesn't have anything to do with the house system or cabling. When I say "the hum is coming off the jack", I MEAN IT! (as opposed to if I didn't know, I'd say "errr ummm my speaker thingy has a weird noise in it!")

Duck, I'd think with my posting history on this site you would know that I've done basic trouble shooting, but that's a different subject.

While the problem did occur mid run, that doesn't mean it was my fault. It could easily be a coincidence. Obviously, during rehearsal I'm not going to stop and pull open the board. I wasted a perfectly good channel of gating on that aux to make it go away (oh, by the way, the problem also wouldn't have gone away when I did this if it was the amp or the speaker).

Any other intelligent thoughts?

 

[Anonymous067]

True, but if it started happening in the middle of a run, IMO, it's better to just work around a simple problem like this than try to fix it by taking the board apart or changing things.

That's fine, if you have 8 auxes and don't need all 8 of them. I have 8 auxes and could have used 10, if not 12.

 

[DuckJordan]

That's fine, if you have 8 auxes and don't need all 8 of them. I have 8 auxes and could have used 10, if not 12.

How old of a mackie console... It sounds similar to what happened with one of mine just before that out went completely out. The older mackies seem to have issues with ribbon cables... I have yet to figure out what could fix the one that i bought from a user on here.. (yes i bought it knowing it wasn't fully functioning). It may be worth the 40 bucks to have a local shop take it apart and have their tech look at it.

 

[Anonymous067]

How old of a mackie console... It sounds similar to what happened with one of mine just before that out went completely out. The older mackies seem to have issues with ribbon cables... I have yet to figure out what could fix the one that i bought from a user on here.. (yes i bought it knowing it wasn't fully functioning). It may be worth the 40 bucks to have a local shop take it apart and have their tech look at it.

It's an SR56-8. Installed in '01, built in '00.

I'll never convince anyone to deal with it...the argument they use is "nobody in the building using all the auxes except you".