Phonic A540

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Hello there.

Hopefully someone can help. I have access to a pair of Phonic A540's that I occasionally use as monitors/speakers for a Roland drum kit. These are active speakers, with one used for the right signal, one for the left signal.

They were last used by a DJ however at full volume until something happened to them...

Currently, there is no sound from the HF speakers. I have opened these up and both diaphragms seem to be fine, no visible damage at all.

When in use, the only sound is a rather muffled bass sound from the bottom woofers. Again though, both these speakers seem to be visually fine.

To me that leaves only the amp itself. This is also where my knowledge runs out, so any help/advice would be appreciated.

On inspection, all seems fine, apart from two round black "doughnut" shaped components. (I'll attach a photo later...) In each amp, one would appear to have come loose where it is soldered to the board. They both have two connections, so I would assume both are meant to be attached to complete the circuit.

I am wondering if this the source of the problem, as would seem obvious, but as mentioned there are two of them, and in each speaker, it is a different one that appears to have come loose.

I'm wondering if they form part of the crossover board which would explain the lack of noise coming from an otherwise good looking speaker?

Any help would be greatly appreciated, especially as I may get to keep them if I can repair them.

Looking at the tweeter diaphragms won't tell you if they are open. Pull the wires off them and measure their resistance. Are they open?

Both speakers have the same problem. What are the odds the exact same part would go bad in both of them at the same time? Now consider that the DJ probably just cranked the things and blew the tweeters. I have a customer on the way to pick up his pair of speakers as I write. And that is exactly what happened to him. I replaced two open diaphragms.
Hello again.

Many thanks JonSnell and Enzo. Took your advice and replaced one of the coils as a test and seems to have solved the problem. Will get a second coil ordered and hopefully be drumming in stereo again soon. Oh, and they'll be kept far away from that particular DJ.

Many thanks again and take care.
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