SM58 strange cutting out issue- think it's solved but advice.

conanthewarrior

New member
Hello, I managed to get myself a vintage SM58, sometime from the 60's-early 80's in perfect cosmetic condition. It is dual impedance, has a second wire inside so you can wire it for 50 or 150 Ohms, Shure stopped this on newer models.

Onto the problem. There was a obvious issue, as a wire inside was broken. Simple enough I thought, so soldered it back in place. It then worked, but as I screwed the top of the mic back on, the connection would cut in and out.

I tried re soldering about 10 times, and then got it working. Soon enough, it cut out again.

This time, I realised there is a bolt in between the solder points, that was very loose. I tightened this up, and the mic is not cutting out now. This bolt is present on my new SM58 too.

I've screwed it back together, so the simple thing to do would be to not open it again. I just wanted to know exactly what this bolt does, and why if it is loose it would cause the mic to cut out.

It looks like something was soldered to it at one point- I've looked at the schematic, and believe it is something to do with the earth(I could be wrong). Instead of the bridge from pin 1 that earths to the base of the XLR, there is a black cable from pin 1 that runs up inside the mic. The orange cable is unused and is for the other resistance.

So, should I leave it how it is, as it is now working, or should I solder something to the place next to the bolt? I'm weary of opening it as it took so long to get working.
Also, what is the bolt for?

Thanks, Conan.
 
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Hi Conan,
A few pics would help but, from memory, when you open a 57/58 the capsule side should have a visible nut retaining a little board that has lugs for your +and-.
If that's what you're describing, I don't think anything solders to it; The chassis of the mic is connected to pin 1.

There have been variations over the years, all the same, so yeah...Pics. :)
 
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