EV Re-20 Repair

[dmp]

I had my second RE-20 go bad with a 'rattle' / distortion, which seems to be a common problem with these.
The first, I sold not working, the second I decided to attempt a repair.

This is NOT the more common problem of deteriorated foam. This 'rattle' occurs when a little plastic piece under the diaphragm comes loose. On both of my mics, I could see it moving around under the diaphragm once the mic was disassembled. There are plenty of other threads describing how to take apart the mic. I'm just going to show a few pics on the re-glue repair. Word of warning: this is very difficult and it would be very easy to botch completely.

The first step is to desolder the magnet wires and remove the diaphragm and metal plate it is attached to. Removal and reassembly of this plate is the most difficult step, because there is a powerful magnet holding it down and losing the orientation could easily mush the wire coil. Try to lift the metal plate directly up and off the mic capsule.  This pic shows the diaphragm plate removed and set aside.

 

[dmp]

Next re-glue the little plastic piece where it sits under the diaphragm. Try to disturb things as a little as possible and keep things clean.

 

[dmp]

Reattaching the diaphragm is as difficult as removal (maybe more difficult). Try to bring it straight down onto the capsule without the coil getting caught or pinched, and route the magnet wires through the correct passages.
Re solder the magnet wires. I had a tough time resoldering them because the exposed wire had broken off on removal, so I had to restrip the coating on the magnet wire. I stripped the wire back a little bit by heating with the iron.

 

[dmp]

And big thanks to MicDaddy who gave me some good tips before I jumped in on this. 

 

[ln76d]

Thanks, good to know

In my PL20 i reattached the diaphragm but without desoldering coil windings. It was a painfull work
Good, that the coil wire is thick and long enough to do it.

 

[zebra50]

Thanks for this.

Is the top plate glued as well as held by the magnets? The one I have seems stuck pretty firmly!

Cheers
Stewart

 

[dmp]

Yes, I think so - I cut some adhesive goo at the edges with a razor blade.

 

[dmp]

I tried a repair on a older PL-20 last night and found this disassembly is near impossible. On the older capsule, there are small metal rods that descend from the top plate through the magnet and held with metal flanges. So instead of being able to pull the top plate  and diaphragm off after cutting a bit of glue, the rods keep it very much in place. I could not get the flanges off to release the rods (covered in glue) and completely ruined the capsule trying to get it apart. It had a stuck diaphragm.

 

[nozzie8]

dmp, would this be considered an older model? I'm having a heck of a time trying to unsolder the voice coil, as it's shrink wrapped, glued and soldered to the metal contacts. It sounds like there's no hope for me even if I succeed in that step. I assume these spiky rods are what you're referring to.  :-[

(Apologies for the blurry picture)

 

[MicDaddy]

8)

 

[nozzie8]

Ben, thanks for the quick reply! I sent you an email about this one a while back, but I understand you probably get millions of those, no biggie. This is an eBay find that was advertised as "needs refoam," but apparently that wasn't all. Yes, the black button is intact, but loose under the diaphragm. I'd love to hear some of your ideas.

 

[MicDaddy]

8)

 

[nozzie8]

Right. So just cut the glue around the diaphragm...(shudders in true DIY sadism). What do you recommend for gluing the diaphragm back to the faceplate? I was planning to use liquid weld epoxy for the pole piece; would that safe on the diaphragm material as well? Thanks.

 

[MicDaddy]

8)

 

[nozzie8]

I don't know if I can bear to own an RE20 and NOT use it on the bass drum, so I need to secure that pole piece for that reason. I will attempt the repair. Thanks so much for your advice.

 

[MicDaddy]

8)

I hope to have an aftermarket diaphragm/coil assembly before the year is over for DIYers to have a more viable means to a field repair.

 

[nozzie8]

I did it! It was a breeze due to the advice. Put it back together--no output except ground hum.  Disassembled and messed with coil leads--tested good, and I got a few seconds recorded as evidence. Put it back together--nada, zilch.  Spent more time and solder to no effect. All connections look good, and coil's moving. Don't know what to do besides send it to EV for new innards. :-[

 

[MicDaddy]

8)

 

[Marooned]

I also have an RE20 with the plastic piece under the diaphragm rattling.  Didn't' realize this until after 4 hours of recording vocals which sounded distorted.  I've looked at your post and I'm trying to figure out a few things.  When you mention desoldering the leads, I assume you did this in the body and not at the diaphragm...and someone also mentioned not desoldering at all.  I'm good with solder but trying to find the best way to accomplish the removal of the diaphragm and wires.  And what type of glue did you use on the plastic piece and what did you use to remove the glue from the diaphragm?  Any help would be greatly appreciated.
Thanks.

 

[midwayfair]

Man, I tried this repair last summer.

I ... do not feel bad that I failed.