Help with a "simple" fix on a 60's AKG D19 diaphragm

[JML in NYC]

Hello all, thanks in advance on this DIY project:

Repairing a 60's AKG D19 with a loose center diaphragm cone. The small diaphragm cone of mylar has come loose and is knocking against the coil causing noise in the signal. Not sure how best to re-secure it (the black contact lens looking thing in this pic). If someone with knowledge and experience wouldn't mind walking me through this I'd be grateful.

I've removed the capsule screws and removed the diaphragm cover, exposing the mylar as shown in the attached pic. The gold mylar ring and paper gasket seem to be glued to the base of the housing (and attached to the coil I believe!) so I set it on my static mat and walked away & came here for guidance. Any thoughts on this?
How do I get to the cone inside and how to I re-secure it?

Thank you very much!

 

[Khron]

I'm no expert, but i believe the voice coil is / was supposed to be attached to the bottom outside diameter of the domed part of the diaphragm.

https://digilab.libs.uga.edu/scl/files/fullsize/a18fa29814ad6e3fab938069115b3a9a.jpg

 

[JML in NYC]

Thanks Khron - Looks correct. Hmmm... now how to reattach it?

 

[MagnetoSound]

To be honest, it’s not something I would even attempt to do myself. Member @panman is likely your man to advise, or to take the job.

 

[k brown]

These types of dynamic mics are made just like loudspeakers - tiny voice coil glued to the outer rim of the center dome. Repairs of these are just as impractical for most DIYers as similar repairs to loudspeakers.

Generally, the diaphragm and attached voice coil are replaced as a unit, where such replacement is possible. In most dynamics, replacement of the entire cartridge is done.

 

[ZHOUJUN]

There is almost no possibility of repairing a dynamic capsule of this type of structure, and the only option is to replace it with a intact capsule of the same type.

 

[MagnetoSound]

There is almost no possibility of repairing a dynamic capsule of this type of structure, and the only option is to replace it with a intact capsule of the same type.

Almost.

 

[JML in NYC]

Welp, I fixed it thanks to PANMAN's advice!!! I have never fixed a moving coil diaphragm but I disassembled it and used a tiny dab of Pannax glue and fixed it! Sounds like new again! ZHOUJUN mentioned it was nearly impossible... but that's not true. I am by no means a tech by any measure and I found it a fairly easy fix and I pulled the whole thing apart, down to the copper and paper rings holding down the mylar. The trick is to not break the moving coil strand wire which is thinner than a strand of hair. Requires a steady hand but other than that, the job is simple. I LOVE my D19 now. It sounds like new again!

 

[jonnyk]

Welp, I fixed it thanks to PANMAN's advice!!! I have never fixed a moving coil diaphragm but I disassembled it and used a tiny dab of Pannax glue and fixed it! Sounds like new again! ZHOUJUN mentioned it was nearly impossible... but that's not true. I am by no means a tech by any measure and I found it a fairly easy fix and I pulled the whole thing apart, down to the copper and paper rings holding down the mylar. The trick is to not break the moving coil strand wire which is thinner than a strand of hair. Requires a steady hand but other than that, the job is simple. I LOVE my D19 now. It sounds like new again!

Hey JML, could you please elaborate? I have a D19 with the same problem, plus the previous owner informed me he accidentially pushed two of the three screws used to secure the grille into the capsule.. I am new here so please bear with me, I can’t seem to find a thread by user PANMAN about the D19. Any help is greatly appreciated, I do not want to put the mic into disrepair with stupid mistakes..

 

[JML in NYC]

Hi, sorry not sure what you mean by you “pushed” three screws. Pushed them where? The three set screws need to clear the outer metal removable grill so you can access the diaphragm. If they are stuck you’ll need to get em out to do any kind of repair.worst case you’ll have to drill them out carefully.

My fix required disassembly of the diaphragm entirely (seperate layers of metal and paper) and re-glueing the cone. It is supposed to be glued down permanently but over time the glue dries out and it comes loose and starts to flop around underneath the mylar. It looks like a black contact lens and is made of metal. A dab of Pattax glue on there (and nooooowhere else) and you’re gtg. Hope that helps bud.

 

[Tubetec]

Well you can either let a broken mic gather dust or get stuck in and see if its fixable ,
sometimes you'll win , sometimes not , but you'll always learn something in the process .

 

[panman]

Hi, sorry not sure what you mean by you “pushed” three screws. Pushed them where? The three set screws need to clear the outer metal removable grill so you can access the diaphragm. If they are stuck you’ll need to get em out to do any kind of repair.worst case you’ll have to drill them out carefully.

No! The three set screws need to go in and not out, but not far enough in to drop inside the capsule. They are meant to hold the capsule and the grill on place. So, they are tightened out.

 

[panman]

To be more clear, the set screws go in and then you can remove the grill and the innards, if you also have removed the screws, where the connector is and also the screw retaining the collar-ring. So, once more, you don`t screw the set-screws out, because then the three holes become too big and the grill and the capsule cannot be tightened anymore.

 

[Paul W]

Hey JML, could you please elaborate? I have a D19 with the same problem, plus the previous owner informed me he accidentially pushed two of the three screws used to secure the grille into the capsule.. I am new here so please bear with me, I can’t seem to find a thread by user PANMAN about the D19. Any help is greatly appreciated, I do not want to put the mic into disrepair with stupid mistakes..

I can't find it either. I did find a thread on D12 repair, but a couple of the crucial posts are suffering from link rot and the pictures don't show. (At least for me. And the pages are excluded from the Wayback Machine BTW... are all groupdiy pages excluded?)