EV RE20 output transformer info

[christopantz]

Hi,

I’m working on refoaming an old EV-RE20, and in the process I snapped a wire right where it exits the transformer, and there isnt enough wire left to solder a new one on. I’m hoping to buy a new transformer but can’t find any info on it. The transformer in my mic is marked “15359 486-0312”.

Im wondering if anyone has any info, or can point me toward a suitable replacement?

 

[pucho812]

have you asked EV?

 

[christopantz]

have you asked EV?

Yes, although couldn’t get an answer from them — in the service manual it says the individual components of the part that houses the transformer and pcb aren’t field repairable. Waiting to hear back from them on if they can sell me the whole assembly.

 

[Whoops]

Probably, You can only order the full cartridge (capsule+transformer)
So thats an option

Another option is to try to unwind 1 turn of the transformer, they you would have enough wire outside to be able to solder it or to extend it

 

[Rusan]

Full Compass can order item # F.01U.110.744, "Mic Element for PL20 and RE20" for $366.83, which of course is only $82 less than a brand new mic. IIRC, since Bosch bought EV it's now a flat-rate fee of something like $275 for all microphone repairs, which by comparison would be a great deal IF that indeed covers cartridge replacement (which I doubt).

 

[CFB4]

The transformer assembly (transformer + plastic housing + switches etc.) used to be available as an EV part, I ordered it for my RE20. It is separate from the capsule assembly.

 

[christopantz]

The transformer assembly (transformer + plastic housing + switches etc.) used to be available as an EV part, I ordered it for my RE20. It is separate from the capsule assembly.

Right on—they just got back to me via email and said they don’t have that part anymore so hopefully I can fix this myself

 

[abbey road d enfer]

Right on—they just got back to me via email and said they don’t have that part anymore so hopefully I can fix this myself

This isn't right. RE20 is a current product, they should have spare parts for it.
Do they propose an alternate solution?

 

[christopantz]

This isn't right. RE20 is a current product, they should have spare parts for it.
Do they propose an alternate solution?

Yeah, to send it to them for a flat repair fee of $315. Go figure.

 

[lukas]

Some pics this transformer?

 

[christopantz]

FWIW, I think I was able to fix it by unwrapping the tape around the transformer and resoldering wires, but I won’t know for sure until I put the mic back together after I have the new foam. I did some quick measurements and I’m getting 3.3ohms on the primary and 33ohms on the secondary, which seems to make sense. Not bothering to measure frequency response right now but I will if I end up having to replace the transformer.

 

[christopantz]

Ok, an update. I managed to get the mic working, although it had very very low output and very very low bass response—much lower than other RE-20s I’d used. I followed all advice here but couldn’t fix it—no rattle in the capsule, although the plastic cap in the center of the voice coil did seem slightly off center.

Anyway, against my better judgment, I decided to venture further and take apart the capsule. I wasn’t getting use out of the mic with how tinny it sounded, so didn’t have much to lose. I desoldered the wires to the capsule and cut the adhesive holding the diaphragm and voice coil in place and removed it.

My first mistake: in the process of cutting away the adhesive I accidentally cut the super thin coil wires where they come out of the voice coil assembly. No big deal, I thought, as I’d repaired guitar pickups before and could just unwind some extra wire from the coil and solder that back.

My second mistake: trying to unwind some extra wire from the coil. I absolutely destroyed the voice coil. A complete lost cause.

Let me be an example of what not to do—a cautionary tale. I got this mic pretty cheap so not super upset, but it’s a bummer nonetheless. You win some you lose some. At least I got some insight into how a dynamic mic works. Here’s hoping me sharing this info will produce some good karma for me the next time I try to repair something

On a related note, if anyone is looking to buy parts of an old RE-20, I’ll give you a good deal. Alternatively, if anyone is selling an RE-20 capsule for a good price, I’m interested.

 

[abbey road d enfer]

My second mistake: trying to unwind some extra wire from the coil. I absolutely destroyed the voice coil. A complete lost cause.

Although it was clear from the start that the problem came from the transformer, you managed to butcher a capsule that was probably perfectly working.

You win some you lose some. At least I got some insight into how a dynamic mic works.

I don't think you learnt how it works, no more than one learns about car engines by inflating tires.

 

[christopantz]

Although it was clear from the start that the problem came from the transformer, you managed to butcher a capsule that was probably perfectly working.

I don't think you learnt how it works, no more than one learns about car engines by inflating tires.

The transformer was working fine. I took measurements to ensure that. The problem was indeed the capsule, but I do appreciate the snark.

 

[abbey road d enfer]

The transformer was working fine. I took measurements to ensure that. The problem was indeed the capsule, but I do appreciate the snark.

What makes you so sure the transformer was working?
Your early posts tend to ascertain teh contrary.

 

[christopantz]

What makes you so sure the transformer was working?
Your early posts tend to ascertain teh contrary.

You should reread the posts. Transformer works fine, one of the wires just came loose. Reattached the wire and transformer measured fine, per my July 8 post.

 

[abbey road d enfer]

OK.