Peavey mixer XRS intermittently cuts out

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JACMAN
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Joined: Sun Aug 21, 2022 11:17 am

Peavey mixer XRS intermittently cuts out

Post by JACMAN » Sun Aug 21, 2022 1:20 pm

We have a peavey XRS that works great most of the time. Several times at gigs, usually outside gigs it will randomly shut down for about 10 seconds then turn back on. This might happen once or twice a song or after several. One time we thought it was the power quality( low voltage, voltage spikes?) but last time I monitored the voltage and it was between 113 and 116 volts. We are only running at about 1/3 volume on both the monitors and mains.
Anyone else see this problem or think of a cause?

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dak
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Location: Germany

Re: Peavey mixer XRS intermittently cuts out

Post by dak » Mon Aug 22, 2022 3:36 pm

It's a powered mixer. The obvious cause would be thermal shutoff triggered by a thermal element on the heat sink containing the power transistors. So there either is something irregular heating up the heat sink (like the power amp bias being off, turning the power amp stage into a rail pulling contest) or you are overloading it by using a bad impedance or drawing too much power or locked-off ventilation (cooler broken or vents blocked by bad placement or dust) or for some other reason. Or the thermal element is coupled to a single power transistor which has lost thermal connection to the heat sink and thus overheats on a whim.

The time constants for electronic protections (against secondary breakdown or other power transistor dangers) should be quite shorter than what you are seeing here, so my bet is on a thermal sensor on the sink.

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