EV RE20 "Babby Rattle" Repair

Discussion in 'Recording Studio' started by kfowler8, Feb 14, 2017.

  1. kfowler8

    kfowler8 Senior Member

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    Trying to fix the picture problem. I moved the files to a new folder and it's acting up.

    Couple of troubleshooting ideas. Let me know if you this will work.

    I have an SM57 that I did the transformerless mod on. So essentially the transformer has been pulled and is now just the capsule. I saved the transformer and wired it between two XLR plugs. This way I can make the SM57 stock if I want to by adding the transformer back in the cable line. Works pretty well.

    So I want to test the RE20 to see if my issue is at the diaphragm with the magnet wires or if it's somewhere at the transfomer/XLR connrection. I'll disasemble the RE20 to get to the mic element seperated. I'll then take the mic element and run some jumper wires to the SM57's transformer. I can then test the vocals. If it works fine, then I know my issue is somewhere in the EV20 wiring. If it doesn't then I know my issue will be around the magnet wires.

    Second test is the opposite of this. I'll take the SM57 capsule and run a jumper to the transformer on the EV20. Then test the mic to see if it works. If it does, then I know the RE20 is ok.

    Both are dynamic mics that don't require phantom power. Do you think this will work?
     
  2. DarrellV

    DarrellV Derl Ver.... ERMAHGERD!.........It's a Nerlin! Silver Supporter Premium Member

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    I see them!
     
  3. kfowler8

    kfowler8 Senior Member

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    Do you see the older ones too or just the ones from my last post?

    Thanks,
     
  4. DarrellV

    DarrellV Derl Ver.... ERMAHGERD!.........It's a Nerlin! Silver Supporter Premium Member

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    just the last ones, old ones still gone
     
  5. DarrellV

    DarrellV Derl Ver.... ERMAHGERD!.........It's a Nerlin! Silver Supporter Premium Member

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    Pics are coming back! YaY!

    Got pics up to post #4
     
  6. kfowler8

    kfowler8 Senior Member

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    OK, I think all the pics are fixed now.
     
  7. DarrellV

    DarrellV Derl Ver.... ERMAHGERD!.........It's a Nerlin! Silver Supporter Premium Member

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    Nothing after my post of the diagram. That could be all of them so far...
     
  8. DarrellV

    DarrellV Derl Ver.... ERMAHGERD!.........It's a Nerlin! Silver Supporter Premium Member

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    Oh, and I think I figured out the problem! You're left handed, you've been going about it backwards! :shock:

    (oh I'm a riot, Alice!) :slap:
     
  9. kfowler8

    kfowler8 Senior Member

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    No wonder I'm out of phase! Har.

    everything should be all set now with the pics.
     
  10. DarrellV

    DarrellV Derl Ver.... ERMAHGERD!.........It's a Nerlin! Silver Supporter Premium Member

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    Should be close enough... A coil is a coil at the end of the day.

    The unknown is the load or impedance match between the two coils and transformers. You could measure coil ohms for fun.

    Also the transformers to see if their input resistance is close. That will at least hint at if the windings are near the same on both.

    Interested to hear the results. Still wondering if you missed soldering a leg into or out of the transformer. Looks like it's tucked right under the capsule in your pics.

    here's a better wiring diagram:

    [​IMG]
     
    Last edited by a moderator: Apr 23, 2017
  11. kfowler8

    kfowler8 Senior Member

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    I'll go back and check my connections. That certainly possible.
     
    Last edited by a moderator: Apr 23, 2017
  12. DarrellV

    DarrellV Derl Ver.... ERMAHGERD!.........It's a Nerlin! Silver Supporter Premium Member

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    In response to your question about how the whole thing works I took a little liberty (sorry) and put these together from EV's statement on how the thing works.
    Hope it's helpful to somebody!

    [​IMG]


    [​IMG]

    [​IMG]
     
    Last edited by a moderator: Apr 23, 2017
  13. kfowler8

    kfowler8 Senior Member

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    Good stuff!
     
  14. DarrellV

    DarrellV Derl Ver.... ERMAHGERD!.........It's a Nerlin! Silver Supporter Premium Member

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    Can you take some of the same pics of how it looks now?

    I've got some ideas, but I can't see how it looks now as opposed to before.

    I also think I know what the coil under the head is.

    It looks like the transformer is down in the base unit (black plastic with all the solder lugs on it) I would like to see more of that area too.

    This mic was advertised as having a humbucking coil for noise immunity (no kidding).

    I'll bet that's what's under the capsule.

    Again, polarity would be key to full response, just like in a pickup, I would think....
     
  15. kfowler8

    kfowler8 Senior Member

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    I'll take some more pics tonight and post them. Thanks for all your help
     
  16. kfowler8

    kfowler8 Senior Member

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    So let me start out with this quote:

    "Success consists of going from failure to failure without loss of enthusiasm." - Winston Churchill


    I'm afraid I crashed and burned on this. First some pics of the new wiring. If you compare to the original pics, it appears to all be wired correctly.

    [​IMG]

    [​IMG]

    [​IMG]

    More comming...
     
  17. kfowler8

    kfowler8 Senior Member

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    So I tried a bunch of different experiments last night. Using the SM57 transformer and capsule didn't work. I suspect there a significant impedance difference between the two.

    I took the mic completely apart and ran jumper cables to the connections so I could easily swap connections. The mic works but I still get the significant loss of bass. I also de-soldered the magnet wires to see if this only happens to pick up the bass but that didn't work. The mic doesn't function at all which tells me that I did have a working contact between the two magnet wires and the posts.

    I suspect that Darrell may be correct in that the mic is either somehow pressurized or specific parts are glued down in order to capture the full frequency. This would go in line with what the EV tech told me in that the mic will no longer work since it's been disassembled. I wish I knew exactly how ben@macdaddy was repairing these.

    I noticed another issue as well. It looks like the magnet coils got disturbed when I placed it back on the magnet. You can see them in the pic below. Not sure what impact this is having but it can't be good. It's the pinkish red wires in the middle here.

    [​IMG]
     
  18. kfowler8

    kfowler8 Senior Member

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    So at this point, I think the repair is a bust. It was fun trying. I'd love to try this again if I found a mic for really cheap.

    I paid $150 for the mic. It's $230 including return shipping for me to send it to EV for repairs. So all in, I'm looking at $390 including shipping to EV. The mic sales for $450 brand new.

    So I don't think I got that great of a deal. I'd be a lot happier if I only paid $100 for the mic. That being said, EV said you're basically getting a brand new mic back. Including warranty. He said the only part they keep is the housing. So I guess I could look at it as I'm getting a brand new mic for $390 even though the housing is scratch up in one spot. For how I use it, it should last me a lifetime. I'll primarily use it for vocal and guitar.

    Anyway it's been fun. Thanks to Darrell for his help.
     
  19. DarrellV

    DarrellV Derl Ver.... ERMAHGERD!.........It's a Nerlin! Silver Supporter Premium Member

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    Uhh, yeah. That's a big problem right there.

    That alone would cause every issue with the sound you have described.

    That coil would be binding against the sides of the gap restricting the movement of the diaphragm. Loss of bass (which has the longest excursion of the diaphragm) and overall volume would be a logical outcome.

    Add to that the wire itself may be damaged and shorting internally essentially creating a 'smaller' coil area generating less voltage per amount of movement.

    Toast....

    I am sorry.. I too was hoping for a better outcome for you.

    Maybe you can find a junker on fleabay or CL for parts and try again...
     
  20. kfowler8

    kfowler8 Senior Member

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    I don't see any at the moment. It would have to be really cheap. I don't know that it would be worth it. Pretty sure I'm just going to go to EV at this point.
     

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