Question about QSC MX1500A 2-Channel Amplifier

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Long startup When I turn on my amp (QSC MX1500a) one channel switches on immediately, the other channel doesnt. Heres whats happening...when the mixer turns on, the red light under "prot" (which i assume means protect) turns on and then it clicks over to the green "pwr" light. Well, one channel takes about 15 minutes to switch over. This has never happened before. Eventually it switches over and the channel works perfectly. But why is this happening??? How can i get it to switch over immediately like it used to? Any help will be useful! Thank you so much. Max

Posted by max smilow on


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The circuit is most likely tracking output DC offset. This offset is floating slightly above the trip theshold level. These levels tend to stablelize during warmup. So, you can find the offset adjustment pots and adjust to as close to zero as possiable. But beware,there likely is a leaky cap or semiconductor causing this unbalance. The relays don't latch untill the green led lights, so the relays are more than likely fine. Best of luck.

Posted on Dec 07, 2008


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Problem is a bad relay. Temporary solution is to clean the contacts. Permanent solution is replacement.

Posted on Sep 30, 2006



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There is a bad connection in the other channel or the speaker relay has a bad contact in it.

Posted on Sep 30, 2006

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Hope it may help you;


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