Sony ECM-377 problem

[mkiijam]

Hi Guys,

I'm working on this Sony ECM-377 that seems like it has low output. When I really crank it, it "sounds" fine. I mean it sounds like a mic to me. The body and grill etc, seem REALLY sensitive to be touched. Like not in a bad way, just like it's WAY more sensitive to telegraphing mechanical sounds then sound pressure waves into the capsule, if that makes sense?

Anyways. This mic is a Electret? Is this a symptom of that going weak?

 

[k brown]

"ECM..." in Sony model numbers, stands for Electret Condenser Microphone.

Touching the body, grille, etc. will conduct noise into the mic, because all the vibration isolation is in the shock mount at the bottom of the yoke; the stand attachment point.

It does appear that vanishing output is common with this model; seems it was not a 'back-electret', the type that ages far better (all modern electrets are back-electret).

Sony's earliest back-electrets proudly boasted a small black dot containing the letters "BE", denoting 'Back Electret', which the 377 doesn't have.

If it is the capsule that's dying, if it were my mic I'd try replacing it with this:
https://www.ebay.com/itm/3941391435...0//azrgWsCPWq2nrDk62fR4kRv|tkp:Bk9SR4D5qorVYQ
Or, this:
https://www.jlielectronics.com/microphone-capsules/jli-3412/

We'd all love to see a pic of the capsule in this, if you're willing.

 

[mkiijam]

 

[k brown]

Very nice - thank you.

Looks to be be about 34mm - the JLI-3412 should be adaptable without too much trouble.

That capsule appears to be a card-only electret version of the one in the C-37A (back-plate hole pattern is quite different); very interesting.


It's a long-shot, but if you're brave enough to try it - carefully remove the capsule and clean the outer rim, and the mount parts. If they've become oxidized, the electrical connection may be compromised. It looks like the capsule's ground connection is strictly though the mechanical mounting parts.

Most likely the capsule's charge is fading, though.

Likely any electrolytic caps inside will also need replacing.

 

[k brown]

Would also be interesting to see how the capsule would respond to application of external polarization.

Schem for this mic might really take some digging - very little about it on the Web.