QU-16 power surge

[Anonymous]

I need some help with this one, it is new to me. I have never seen this happen before. Recently, I walked into the church and the tech team told me that there was a problem with QU16 console. What they did was plug a Mac Mini into QU16 via the 3.5mm headphone jack and then the ST1 connection on the console. When they did this, the breaker (power) in the sound booth tripped. When we turned everything back on, and powered everything back up, the power tripped again. After unplugging the Mac from the console, everything was fine, but now I no longer have a sound card on my Mac mini. It no longer is seen in the system information of OSX.

We tried connecting iPads and Android phones to the same jack and it worked with out issue.

The following week we repeated the processes again, this time with a Macbook Pro and everything worked just fine. This time we connected the Macbook Pro to the ST3 connector, thinking something might be wrong with the ST1 or 2 connector. Everything worked just fine with this setup and service went well. Then just last night for our Sunday night service, the exact same problem happened with the Macbook Pro and the ST3 connection. Now the MBP doesnt have headphone output.

Anyone have any idea what might have caused this and will it happen again if we get a USB audio device for our Macs?

[Dick Rees]

Same cableing?

Sounds like a short somewhere or possibly reversed polarity on the power outlet.

[MarkPAman]

When you say the power tripped, what sort of trip is it? They tend to be there for a good reason!

Trips tend to be designed to trip if the current gets too high, or if they detected current leaking to earth, depending on the type. Both of these faults are potentially dangerous. I’m wondering if you have incorrectly wired mains, and the connection between desk and computer is allowing a path to ground, causing the trips to do their job, and blowing headphone amps while it does it.

I’d recommend that you switch off & unplug all your audio stuff, until you can get all mains supplies & leads checked by an electrician.

[GCumbee]

In my decades in this business I have never seen anything like that happen. Truly weird.

[Anonymous]

This is the same audio setup we have been doing for over 1.5 years. The cables are the same. There is other electrical work being done in the building but not in the main hall. That could be possibly causing it but they are separate panels all together.

All of the audio equipment is on the same outlets, that they have always been on. Same setup. Im actually taking the same setup to another building on the campus tomorrow to see if I can reproduce the problem.

The console is plugged into a surge protector, the Mac’s both were plugged into the same surge protector when this occurred at different times.

As far as the trip of the breaker panel, I will get an electrician out to see what the problem is.

[Dick Rees]

Take a meter and see if you have any voltage on the ground.

[Anonymous]

On the ground of the outlets that the console and the computer is plugged into?

[Dick Rees]

Yes. Odds are that this is an electrical supply problem. Best get a pro to check it out. These things can be dangerous even if you haven’t experienced any problems over time. Reversed polarity and/or jury-rigged grounding can put voltage where it shouldn’t be.

[Anonymous]

Thanks. I will report back tomorrow and let you know.

[GCumbee]

Like others have said, only way a signal line could trip breakers is if there is a frayed cable or something that is get supply voltage onto the signal cable. Highly unlikely but nothing else explains that kind of anomally. I have seen one case of a frayed extension cord touching a rack case that got onto a mic line and a singer was shocked badly but survived.

[JLargent]

An audio connection causing an electrical circuit breaker to trip and killing third party sound cards. Truly the strangest problem I’ve ever heard! I wish I had something more than condolences to offer. I hope you find the problem without any more damage and please post about it. I’m putting a Bluetooth receiver on my ST3 right now!

[MarkPAman]

“Thanks. I will report back tomorrow and let you know.”

Any news?

[Anonymous]

Hopefully the investigation wasn’t fatal 🙁

[Author]

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