Oh bugger. At least I made this mistake on a cheap capsule ...

Kids, don't try to remove screws from a capsule without covering it.

I was replacing the capsule in my 251 build, and after removing it, I started taking off the wire leads so it would fit in the capsule box. The screwdriver slipped and boink right into the diaphragm.

Funny thing is, it doesn't look punctured. I think it might still work (and certainly if I use it one-sided), but it'll probably never sound the same and the Campbell capsule is now staying in the 251 for sure.

So before I go popping this into a test microphone -- how bad is it? Is it fixable without reskinning the capsule? Does this short the membrane to the backplate if it's "stuck" and is there a way to get it unstuck?

If it's just a ding and not a puncture, it will probably still work. You can test it in a mic. If there is a problem with it, it will present like low end thunder (most likely).
If you have a capacitance meter, you can test the value out of circuit between the diaphragm and the backplate. Look for it to be really close the other side in value.
What kind of capsule is it?

Dave

wave said:

If it's just a ding and not a puncture, it will probably still work. You can test it in a mic. If there is a problem with it, it will present like low end thunder (most likely).
If you have a capacitance meter, you can test the value out of circuit between the diaphragm and the backplate. Look for it to be really close the other side in value.
What kind of capsule is it?

Dave

Click to expand...

Thanks, Dave.

It's an edge-terminated 67 type from Studio 939. I had tried to get an extra one in the group buy, but I ended up with four 47s instead, so I'm interested in having it in working condition for some testing but a replacement isn't in the cards at the moment. I'll go ahead and hook it up. I guess the worst that happens is that I short -60V to ground through a 1G

I'll also measure the capacitance, if all I'm looking for is a similar value I don't have to worry about my meter's lousy performance on pF measurements.

http://uk.rs-online.com/web/p/trimmer-resistor-adjustment-tools/8524611/

Get one of those for when you have to work on an expensive capsule. Makes it impossible to slip, and literally risk free.

Most cheaper capsules come with Philips screws, but this tool will work on any cheesehead slotted screw (DIN 84) in M1 to M2 sizing (Neumann, AKG, Thiersch, Campbell etc. are all DIN 84)

Oh my...

I feel you...

the same happened to me, but with a Heiserman 87 capsule :
It seems that I punctured mine, so I use my D87 only in cardioid since the damaged side produces unbearable noise.
I got the tool Banzai posted immediately when it was on here some time ago... Ingenious thingy indeed...

Best

Couldn't get it working again. A member offered to re-skin it, which I might do at a later date when I get the funds. It's definitely shorting against the backplate, though -- nothing but hum when I hook it up, sounds exactly like what happens when I over-bias a capsule and the membrane collapses.

Bummer. I slipped with my finger, completely unawares, and managed to blemish a brand new Red Line capsule from Thiersch. Cost me a chunk to get it fixed again.

I like to think of myself as fairly agile but the truth is, sometimes I'm an awkward dope.  :