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EXpo system shutting down all the time - PROTECT light
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Author:  gusta_ve [ Sun Jan 27, 2019 11:42 am ]
Post subject:  EXpo system shutting down all the time - PROTECT light

I have been gigging with my band using two Fender Expo speakers for about 3 years. Last week, one of the speakers didn't work well since I first plugged it in: my voice or any instrument would sound for a split second, and then the red "PROTECT" light would come on and mute the system down. The other Expo speaker was chained to the outputs of this "faulty" unit and continued to sound well, with no problems. I tested the speaker at home using the RCA input and my phone, and the same thing happens at a somewhat high volume. The speaker works well and sounds good until I crank it up; then it shuts down the same way every time. Any insight?

Author:  ContraCaller [ Thu Mar 07, 2019 7:53 am ]
Post subject:  Re: EXpo system shutting down all the time - PROTECT light

I was hoping someone else would answer this. [sigh]

Okay, the system protects itself from overheating with a thermal-triggered circuit breaker. It sounds like your speaker is overheating, probably because of either a failing circuit or a failing thermal sensor. Either condition implies testing at a repair facility.

Another possibility would be that vertical plug where the towers plug into the base. If something spilled into that, leaving a conductive residue between the holes those big posts on the towers plug into, then the electricity powering the tower would short out. If there's a short between those posts (or between the holes the posts plug into), then that would overheat the power amp really quickly. Make sure that socket is clean -- but DON'T spill any liquid cleaner down into it, especially while it is plugged in.

While it is unplugged from AC power, vacuum it, wipe it, and maybe wipe it with a damp cloth, but don't let it get wet enough to conduct electricity.

The plugs in the back of the subwoofer are "line level" signals, very weak, very little electricity being used, measured in milliwatts. The plugs in the top of the subwoofer that the towers plug into are speaker-level signals, a couple hundred watts. At that level, electricity can generate heat really quickly, if it shorts out.

I think the Expos are something like 380 watts, but most of that goes to the subwoofers, since bass notes require more wattage, but the towers probably pull over 100 watts. It's a bad thing to short that out.

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