Open speaker and audio amp measurement questions...

rmcelwee

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Open speaker and audio amp measurement questions...

I have a Blasteroids cabinet with two speakers driven by the audio pcb and a subwoofer driven by a separate amp (they call it a House Quake pcb). The subwoofer is working but only one of the speakers is working. I pulled the speakers and one showed 8 ohms but the other was open. OK, bad speaker... BUT, before I grab another and install it I wanted to make sure the amp isn't going to ruin it since I probably don't have many spares. I wasn't exactly sure how to test the output from the amp but I noticed that the wires for the working speaker were showing a bouncing 2.9 to 3.0 mV and the wires for the blown speaker were showing a bouncing 4.9 to 5.0 mV. I thought I could have seen like a 12V reading coming from the amp to the speakers but I could not. So, my questions:

1) How do you really see if a signal is going to the speaker?

2) If mVs are how you see the signal, is twice as much going to the blown speaker what killed it?

3) Fill in the blank. I'm such a novice with this I don't know what else to ask.
 
swap speaker connections. if the other speaker survives it's not the amp. if the speaker, in a truly unlikely event, dies, then you know it's the amp killing speakers.

I had a speaker on a game where the terminal block where you connect the speaker wires had come detached from the actual cone of the speaker (or whatever that terminology is). I soldered them back together and had no such issue with the speaker knocking or acting strange since.

visually inspect the bad speaker to make sure that's not the case, you'll see the copper wiring of the speaker connecting to the terminals.
 
I checked for resistance on the copper wires under the terminal block as well. No luck!

I'll probably swap the speaker and see what happens. I just threw away a bunch of speakers from some old TVs and wish I hadn't. Would have been ok to blow them up.
 
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