# Mackie board broken channel



## renegadeblack (Oct 27, 2008)

I'm not the sound guy at my school, but I figured I'd ask a question since my sound guy seems to have something against this forum. 

The right channel on our mackie board is broken, I suspect that it's a distinct possibility that there's just a fuse inside the board that got blown. Do you guys think that it would be worth it to crack open the case and see if that's the case being as the warranty is over or should we just leave it to a trained professional? Suggestions?


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## Footer (Oct 27, 2008)

Its not a blown fuse. It could be a host of things, odds are you can not fix it, unless its just a loose ribbon or something to that nature. Take it to a shop.


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## waynehoskins (Oct 27, 2008)

And again, remember, you are a student. Don't open it and try to fix it unless you're told to, because it's not yours.

The only fuse in that thing is going to be in the power supply circuit. Maybe two (one primary, one dc), but probably just on the primary side.


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## museav (Oct 27, 2008)

What model? Are you getting any signal on the meters or on the monitor/headphone outputs?

Mackies seem to have a reputation for ribbon cable problems but another common problem is mains inserts contacts that haven't been used, sometimes inserting and removing a connector in the inserts a few times clears up that problem.


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## tfling (Oct 27, 2008)

If it is a SR40/8 then go ahead and find the money to replace it. These units had several flaws that will eventually make them useless.


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## Footer (Oct 27, 2008)

tfling said:


> If it is a SR40/8 then go ahead and find the money to replace it. These units had several flaws that will eventually make them useless.



Those flaws being? *I have one in my inventory, would like to see what problems might pop up besides the typical mackie stuff*


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## tfling (Oct 27, 2008)

We had one that about half the channels strips had to be replaced on, then the master fader section was replaced, then eventually the power supply died on it. It was a wonderful console, but we just couldn't keep it running.


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## Eboy87 (Oct 27, 2008)

The two problems plaguing Mackie that I'm aware of are loose ribbon cables and insert jacks. If it's the inserts, use a 1/4" jack and work the contacts with it. If it's the ribbon cable, take it in to be serviced.


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## renegadeblack (Oct 27, 2008)

waynehoskins said:


> And again, remember, you are a student. Don't open it and try to fix it unless you're told to, because it's not yours.
> 
> The only fuse in that thing is going to be in the power supply circuit. Maybe two (one primary, one dc), but probably just on the primary side.



I had no intention of opening it myself. If I were to poke my head in there, I'd be totally out of my realm. Our td teaches the electronics classes at my school and I'd have him do it. He's already fixed a bunch of our gear in the short time that we've appointed him our new advisor. The sound guy says that it's a Sr-24-4 vlz pro board. Both of the channels do show up on the (I'm a lightguy, pardon my not knowing the terminology) little LED meter thingy, I think both channels go out on the headphones, but when it gets to actually outputting to the speakers, it doesn't work. The guy who graduated who was in charge of sound before was very thorough so I'm assuming that he tested to make sure that it wasn't a bad amp.


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## Chris15 (Oct 28, 2008)

They say that when you assume, you make an ass of you and me... It should be easy enough to check if the fault does lie in the board, swap the output XLRs and see if the fault moves accoringly. If it is, console problem. If not, system problem...

I second Brad's suggestion of a dirty insert jack. You should be able to listen to the jacks and hear audio. If not, then it's something upstream of there. Before you try that though, anyone else willing to agree or otherwise that a pair of headphones in the insert jack should show the signal on (in this case) the left channel? I should not expect much audio to be found post insert at this point though... The higher the headphone impedance the better for this...


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## renegadeblack (Oct 28, 2008)

Chris15 said:


> They say that when you assume, you make an ass of you and me... It should be easy enough to check if the fault does lie in the board, swap the output XLRs and see if the fault moves accoringly. If it is, console problem. If not, system problem...
> 
> I second Brad's suggestion of a dirty insert jack. You should be able to listen to the jacks and hear audio. If not, then it's something upstream of there. Before you try that though, anyone else willing to agree or otherwise that a pair of headphones in the insert jack should show the signal on (in this case) the left channel? I should not expect much audio to be found post insert at this point though... The higher the headphone impedance the better for this...




Am I assuming something? I must have missed that  The headphones do work in both channels so a dirty input might be the case? I'm going to tell the sound guy to plug in and unplug the wire a bunch of times? Is that what I'm supposed to do?


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## museav (Oct 28, 2008)

renegadeblack said:


> Am I assuming something? I must have missed that  The headphones do work in both channels so a dirty input might be the case? I'm going to tell the sound guy to plug in and unplug the wire a bunch of times? Is that what I'm supposed to do?


If you are getting both channels in the headphones and on the meters, and if the master fader affects the level, then it is not the insert jack as that is before the fader.  Another test would be to monitor the mono output as it simply sums the left and right signals right before the output drivers. If you can pan a channel all left and all right and always hear it in the mono jack then that indicates that everything is good up to the output drivers.

Then again, I just realized that I don't think we ever actually confirmed that it was the mixer. If you are getting level for both channels on the meters and headphones, how did you verify that it is the mixer output and not something after that? If you swap left and right outputs on the console, does the problem swap channels or stay with the one channel?


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## waynehoskins (Oct 28, 2008)

I too am thinking it's a system problem.

Is it a mono or stereo rig?
Is anything plugged into the main R output of the console?
What kind of processing does it have?
Checked signal indicators in the drive rack and amp rack?


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## Eboy87 (Oct 28, 2008)

Chris15 said:


> They say that when you assume, you make an ass of you and me...



The official medical condition for that is cranial rectal inversion, or CRI 

For the OP, I agree with Chris and Brad, this is starting to sound like your problem is downstream of the console. Swap the XLR's between the left and right output and see if the problem still shows up on one of them. 

I understand that you're a lighting guy, but what else is in the signal chain after the console? EQ? Amps? System controller? Just a basic description or name/model number from the faceplate can help.


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## renegadeblack (Oct 28, 2008)

Eboy87 said:


> The official medical condition for that is cranial rectal inversion, or CRI
> 
> For the OP, I agree with Chris and Brad, this is starting to sound like your problem is downstream of the console. Swap the XLR's between the left and right output and see if the problem still shows up on one of them.
> 
> I understand that you're a lighting guy, but what else is in the signal chain after the console? EQ? Amps? System controller? Just a basic description or name/model number from the faceplate can help.



There is an EQ, I'm not sure of the model number or maker, and there's also two crown amps. The guy who I do sound with seems to be determined that it's the mixer, however, as far as I know, he hasn't really tested anything with that and the guy who was there before him who knew everything there was to know about that board and he seemed to think that was the case aswell. We were going to work on it today, but there was a class going on in our auditorium. Hopefully on Thursday assuming that the same class isn't going on, we will be able to try things that you guys have suggested. I don't think he'll be happy to find that his board is fine, he despises the thing  .


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## Eboy87 (Oct 28, 2008)

I could see why he would despise it, but that's gear sluttery, and I try not to get into that mindset... too often  Anyway, I assume (yes, I know the previous points about that) that you have a CD player? Use that, or get someone to stand there with a mic, and go through (one channel at a time) every piece of gear in the system, starting with the console, then the EQ, then the amps. 

Look at the meters on each piece of gear to see if they're showing level. If you find something that you think is suspect, unhook it from the signal chain and see if the channel magically reappears. 

THere are plenty of threads on this board about troubleshooting. If you have a read through some of them, you'll get even more suggestions about how to go about checking all this.


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## renegadeblack (Oct 28, 2008)

Eboy87 said:


> I could see why he would despise it, but that's gear sluttery, and I try not to get into that mindset... too often  Anyway, I assume (yes, I know the previous points about that) that you have a CD player? Use that, or get someone to stand there with a mic, and go through (one channel at a time) every piece of gear in the system, starting with the console, then the EQ, then the amps.
> 
> Look at the meters on each piece of gear to see if they're showing level. If you find something that you think is suspect, unhook it from the signal chain and see if the channel magically reappears.
> 
> THere are plenty of threads on this board about troubleshooting. If you have a read through some of them, you'll get even more suggestions about how to go about checking all this.



I will do this with him soon. I probably should have mentioned that we have a cd player. 

Also, I don't know if this would point you to anything, but the guy who was using this equipment last year had been saying that there were problems where the channel would crackle in and out. I will ask the sound guy to try all of that stuff, mainly because if it turns out that all of his stuff is fine, then I get at the money


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## renegadeblack (Oct 29, 2008)

For those of you interested, I, the lighting guy, was able to fix it. I tried the suggestion of switching the left and the right channel and seeing if that changed anything, and it did. We hadn't really tried much because we both knew that the last guy really knew what he was talking about. I took a look behind the rack (talk about terrifying) and found that apparently after someone installed the EQ, they didn't re-plugin the right channel. I plugged everything in, and sound came out both channels! I was thrilled! I told my buddy and he now agrees that my stuff needs to get replaced, and the guy that came before me I didn't trust a word he said, so I tried everything and have confirmed that it is broken, then again, you can tell by looking at it.

One last question:
In my theatre, we have 4 speakers, 2 on each side. We have two amplifiers, one for each channel. There is a speaker for each channel on each side. So on the left side, we have a speaker for the right channel and a speaker for the left channel, the same on the right. Is this normal? Is there a reason? Should I change it so that only left is on the left and only right is on the right? What's up with that?


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## Hughesie (Oct 30, 2008)

renegadeblack said:


> There is a speaker for each channel on each side. So on the left side, we have a speaker for the right channel and a speaker for the left channel, the same on the right. Is this normal? Is there a reason? Should I change it so that only left is on the left and only right is on the right? What's up with that?


_
Simple trouble shooting steps_

Its it broken?
no, then your fine

the moral is if it working current let it do its job i have seen some strange setups in my time but if their working then don't worry too much about it.


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## museav (Oct 30, 2008)

renegadeblack said:


> For those of you interested, I, the lighting guy, was able to fix it. I tried the suggestion of switching the left and the right channel and seeing if that changed anything, and it did. We hadn't really tried much because we both knew that the last guy really knew what he was talking about.


Sounds like maybe he did not know as much as he thought he did! Or just wanted an excuse to get a new mixer.


> One last question:
> In my theatre, we have 4 speakers, 2 on each side. We have two amplifiers, one for each channel. There is a speaker for each channel on each side. So on the left side, we have a speaker for the right channel and a speaker for the left channel, the same on the right. Is this normal? Is there a reason? Should I change it so that only left is on the left and only right is on the right? What's up with that?


When you say "channel" are you referencing the two channels on the amps or the left and right channels from the mixer? Amps don't really have left and right, they're simply two channels, and what really matters is what signal is at the input of the amplifier channel. Can you clarify how it is actually wired, e.g. the left output of the mixer runs to which amplifier inputs that in turn connect to which speakers and the right output of the mixer runs to which amplifier inputs that connect to which speakers?

Unless it is a cross-matrix system, which it sounds like would be unlikely, then it would be unusual for one of the house left speakers to be getting the left channel signal and the other house left speaker the right channel signal. However, it would not be at all unusual to have the left channel signal run to both channels on an amplifier to power the two speakers on the one side.


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