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Electro Voice SXA Powered PA Cabinet - Baffling Loud Hiss/Static

gerryt

Feb 5, 2021
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I have an Electro Voice SXA 100+ powered PA speaker with a peculiar problem. At times i get a loud fuzzy hiss/static through the tweeter. There is no hiss with the woofer speaker. I tested the tweeter horn driver by connecting it to another amplifier and it works fine. My research online found an Electro Voice data brochure which tells me that the amplifier unit has two output amps built into one circuit board - one for the tweeter and one for the woofer. I have not been able to find a schematic for this unit online. I called Electro Voice and asked for one but they said they do not provide schematics as it is against company policy.

I am not sure if the circuit board has a bad trace that is causing this buzz or if it is a component. I replaced the filter caps but this did not solve the problem. Wondering if anyone has done any work on these units or had some type of similar experience withe something else. I have attached a video link demonstrating the problem. The video shows the problem starting simply by wiggling the wires from the transformer where they connnect to the circuit board, but the loud static can be caused and stopped by many other methods - slight tapping of the cirucit board, wiggling the wires that go to the speaker, softly tapping almost any capacitor on the board. Just looking at it seems to get it started sometimes. My guess is that it has to do with output side of the tweeter amplifier, but I would value second, third, and fourth insights about this one. Thanks in advance for any assistance. Here is a link to the 40 second demo video: https://1drv.ms/v/s!Av_VGYhpqPMihs19f18cJxl4ixQYVw
 

Martaine2005

May 12, 2015
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I would be first checking with a magnifying glass for a bad solder joint/loose connection.
I would probably just re-touch all solder joints on that board as it’s small.

Martin
 

Delta Prime

Jul 29, 2020
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My research online found an Electro Voice data brochure which tells me that the amplifier unit has two output amps built into one circuit board - one for the tweeter and one for the woofer
Link please.
Electro voice data brochure.

Can you take a photo of the solder side of the PCB where the connectors located?
Also be gentle...don't thrash equipment around in your videos.
 

gerryt

Feb 5, 2021
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