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On Again, Off Again Microphone

Discussion in 'Electronic Repair' started by Ron, Feb 13, 2013.

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  1. Ron

    Ron Guest

    I use-- or try to use-- a Radio Shack cassette microphone to record tapes on a Panasonic tape recorder. I don't need an expensive mic, but I want one that works and this one only works sporadically. I'm beginning to notice that these Radio Shack mikes have a limited life span: they'll work great fora few weeks then die a quiet death. the one I have now is working, but I don't know for how long; it may stop working for a week or more-- or it may not ever work again. Does anyone know why these microphones are so unreliable (besides being cheap)? Or better still, a simple way to keep them working?

  2. Sjouke Burry

    Sjouke Burry Guest

    Most of them consist of a FET transistor with the base floating, and
    picking up signal capacitively. So any static spark can easely destroy
    them, when you touch the connector.
    BUT, they are cheap, and sensitive.
    Handle with care.
  3. Phil Allison

    Phil Allison Guest

    "Sjouke Burry"

    ** Hog wash.

    Electret mics are not subject to any such failure mode.

    In any case, the OP's mic is probably dynamic.

    ..... Phil
  4. Ron

    Ron Guest

    Yep, that's the one. Funny how quickly they self-destruct. Almost
    makes ya want to pay that extra five bucks for the extended



    "In the beginning was the rhythm, but I had forgotten and I was
    waiting for the word."

    -- Ray Manzarek --
  5. Phil Allison

    Phil Allison Guest

    "Phil Allison"

    ** The mic capsule is very small and the impedance is 600ohms = lotsa hair
    fine wire used in the voice coil.

    Hair fine copper wire PLUS crappy Pb free solder = recipe for sudden

    Hint: It's the flux....

    ..... Phil
  6. Ron

    Ron Guest

    Okay... I see why they fail, but why the failure, then after a week or a month, it works again for a while?

  7. gregz

    gregz Guest


    Take one apart. Got VOM ?


  8. Is it a condenser mic? They use batteries.

    Mic input on the recorder could have broken solder connections.

    Mark Z.
  9. If it has a battery, corrosion in the battery compartment is the most
    likely cause. Whilst zinc-carbon batteries produce corrosion that is
    usually fairly obvious, the corrosion from alkaline batteries is
    sometime impossible to see. Luckily it is easy to remove with a cloth
    dampened with tap water or with a wetted nylon scouring pad.

    Don't forget to clean the battery as well as the contacts in the holder.
    If that cures it, throw away the original battery and buy a good quality
  10. Ron

    Ron Guest

    Not these days-- a sad story I wont bore you with. But if I had one, what would I be looking for? It's pretty certain that I'll buy one again, and it won't last any longer than an ice cube on a hot day. :)



    "Some success, some failure; but either way the gnawing hunger to know is never sated, and the road to the Unknown continues to be dark and strange."

    –– Control Voice (The Outer Limits) ––
  11. gregz

    gregz Guest

    Continuity. You should also hear clicking using a meter. Lightly pushing
    around the mic element might make the connection good for some instant, or
    it might temporally fix itself. Put leads on connector while doing this,
    and also watch meter.
    I would rather use an analog meter. The wires on the mic are very small.

  12. gregz

    gregz Guest

    This is pretty much curiosity, it's unlikely you can fix mic element. I
    don't think the switch is bad, but it could be the cable connection.

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