Fire in sq5

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This topic contains 4 replies, has 5 voices, and was last updated by Profile photo of Geoff Geoff 10 months ago.

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  • #103807
    Profile photo of Belfast
    Belfast
    Participant

    Had a bit og a scare the other day i came home after doing a gig, i connected my sq to my homesetup as usual
    next thing alot of smoke comes out of the back quickly pulled out power and all connectors
    adter some time i thought ill connect the power just to se what the hell was burned…
    But here is the thing everything works perfectly checked every feature on the mixer and everything works and it havent acted up since
    What !!!

    i will of course send it for repair hoping they will find something…

    Just wondered if anyone have tried that one ?

    Cheers

    #103815
    Profile photo of KeithJ A&H
    KeithJ A&H
    Moderator

    @Belfast

    Sounds like something has been fried there, though if it’s part of the analogue circuitry, the console will not necessarily have any idea and will appear to function correctly.
    I’ve seen this happen before with bad/incorrectly wired connections and/or unearthed equipment that’s grounded itself through the signal path of the console.
    (for example, unearthed monitor speakers connected with either unbalanced cables or other connectors which short ground and pin3).

    As you’re already sending the unit in for repair, they’ll be able to let you know what’s wrong with the console, but I’d suggest checking there is no way any equipment could be trying to ground itself through audio cables, or you might hook it back up only for the same thing to happen!

    Thanks,
    Keith.

    #112894
    Profile photo of Josiah
    Josiah
    Participant

    Hey Keith, I am in America and mostly run off 120V. I had this exact same thing happen trying to connect my amp rack to the mix 7 output on my SQ7. Some smoke came out of the mixer in that area, and the #7 mix output no longer works properly. But all other mix outs and inputs locally on the console appear to work 100% normally. There appears to be no other damage to your point about the mixer not necessarily knowing part of the analog circuitry was damaged. So I think I should be able to use it for my next show before getting it into the shop for repair?

    I have QSC PLD amps and that is what fried it through an XLR cable. I always test my power, and what I can’t understand is why this would happen when my power tester shows me that it’s correct (i.e. grounded, no floating neutral, etc.). This is not the first time I have felt a charge through my amp rack before, but it never fried anything. The breaker popped within 5 seconds when it fried. Do you know how to get an amp rack grounded properly? I’m tempted to run a wire from one of the chassis into a grounding rod, but I don’t know why that would be necessary when the circuit is grounded properly. Please advise anyway you can, as I am at a complete loss as to why my amp rack does this sometimes.

    #113000
    Profile photo of Mike C
    Mike C
    Participant

    I have QSC PLD amps and that is what fried it through an XLR cable. I always test my power, and what I can’t understand is why this would happen when my power tester shows me that it’s correct (i.e. grounded, no floating neutral, etc.). This is not the first time I have felt a charge through my amp rack before, but it never fried anything. The breaker popped within 5 seconds when it fried. Do you know how to get an amp rack grounded properly? I’m tempted to run a wire from one of the chassis into a grounding rod, but I don’t know why that would be necessary when the circuit is grounded properly.

    If your feeling a “charge” at the amp rack that is bad sign! Somewhere is a mis wired plug, maybe a bad power strip.

    #113111
    Profile photo of Geoff
    Geoff
    Participant

    It sounds like you have a wiring error somewhere. Perhaps in the amp rack or the outlet that it is plugged into.

    One possible scenario is a “reverse polarity bootleg ground” or RPBG. A bootleg ground is sometimes found in older homes with 2-wire (no ground) wiring. When a 3-prong outlet is installed, the installer simply connects the ground terminal to the neutral. This will test “correct” with a simple 3-light tester, but it is not safe and may induce a lot of noise into audio circuits. What is really dangerous is when the polarity of the hot and neutral inadvertently gets swapped. Then the chassis is hot, but it still tests “correctly” with the 3-light tester. When the hot-chassis device is connected to one that is properly grounded, sparks fly! You need a non-contact voltage tester (NCVT) to check for this condition.

    Geoff

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