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Thread: Inherent Problem with Yaesu MH-27 Microphone

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  1. #1
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    Default Inherent Problem with Yaesu MH-27 Microphone

    Is there an inherrent or common problem with the Yaesu MH-27 microphone?? My FT-2500M uses the MH-27 and the transmit audio is low. I thought I had read someplace that there were several surface mount components in the microphone that are prone to faillure. Any help would be appreciated...

  2. #2

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    Yes, there is a well known problem with this microphone and it sounds like you have that problem. The electrolytic capacitors go bad and need to be replaced. That's all. Easy fix.

  3. #3

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    Get out your SM soldering tools, solder wick, tweezers and Temp Controlled Soldering Iron.

    The Yaesu MH-27 microphone suffers from the "Bad Capacitor/Capacitor Plague problem".
    Yaesu Service will tell you that 3 capacitors normally go bad inside the microphone.

    Obtain the MH-27 schematic from Yaesu (below). LOOK for leakage !
    http://webpages.charter.net/rlanders...7a8j%20Mod.pdf

    HERE are the MH-27 NOTES from Tim Landers, N4HIG
    http://webpages.charter.net/rlanders904/

    PHOTOS of MH-27 repairs
    http://webpages.charter.net/rlanders..._corrected.JPG

    w9gb

  4. #4
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    Default

    Thank you, that exactly the information I was looking for. Just couldnt remember who had it..

  5. #5
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    Quote Originally Posted by W9GB View Post
    WOW, 3 parts, 1 ceramic chip cap, 1 disc ceramic, and a SM Tantalum all failed simultaneously!!!!!!!!!

    To the O/P: You might want to actually TROUBLESHOOT the thing before you go wildly changing parts.

    Rege
    Now my mistakes travel at the speed of light!:cool:

  6. #6

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    WOW, 3 parts, 1 ceramic chip cap, 1 disc ceramic, and a SM Tantalum all failed simultaneously!!
    As can be read/seen in the MH-27 schematic, all 3 of these capacitors are between the elecret microphone element and the active circuitry in the MH-27.
    Yaesu Service will tell you that 3 capacitors normally go bad inside the microphone.
    As the old saying goes, I don't want to have the microphone on the workbench for 3 visits -- when I can address known problems outlined by the Yaesu service.

    The Taiwanese capacitor plague (industrial espionage gone wrong, circa 2000-2002) has cost BILLIONS of dollars in failed and junked electronic equipment.
    Industry has sucessfully downplayed the extent of the problem, even after a detailed article of the problem in 2002 issue of IEEE Spectrum magazine.
    The leakage can be as damaging as an outright component failure.

    w9gb
    Last edited by W9GB; 11-11-2009 at 09:09 PM. Reason: typo

  7. #7
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    Not a chance that all 3 of those parts failed.

    I'll put money on it

    That's the problem with trying to fix a defective circuit by reading what someone else did.

    Frankly, if a fellow cannot do a simple audio signal trace without asking for step-by-step instructions, he should not attempt to service the equipment.

    Rege
    Now my mistakes travel at the speed of light!:cool:

  8. #8
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    Quote Originally Posted by W9GB View Post
    The Taiwanese capacitor plague (industrial espionage gone wrong, circa 2000-2002) has cost BILLIONS of dollars in failed and junked electronic equipment.
    Industry has sucessfully downplayed the extent of the problem, even after a detailed article of the problem in 2002 issue of IEEE Spectrum magazine.
    The leakage can be as damaging as an outright component failure.

    w9gb
    Except the Taiwan problem was for electrolytic capacitors, and none of those capacitors are electrolytic.

    Rege
    Now my mistakes travel at the speed of light!:cool:

  9. #9
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    Default

    Quote Originally Posted by AI3V View Post
    WOW, 3 parts, 1 ceramic chip cap, 1 disc ceramic, and a SM Tantalum all failed simultaneously!!!!!!!!!

    To the O/P: You might want to actually TROUBLESHOOT the thing before you go wildly changing parts.

    Rege


    Perhaps when I do troubleshoot I will the information on hand. Did I say anywhere where I was going to WILDLY change parts as you put it???

  10. #10
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    Quote Originally Posted by AI3V View Post
    Not a chance that all 3 of those parts failed.

    I'll put money on it

    That's the problem with trying to fix a defective circuit by reading what someone else did.

    Frankly, if a fellow cannot do a simple audio signal trace without asking for step-by-step instructions, he should not attempt to service the equipment.

    Rege


    Unit you have 1st hand knowledge of my troubleshooting abilities, I would suggest you keep your erroneous opinions to yourself..


    Christ someone asks for some information, and gets it and then rest of the peanut gallery has to jump in and give there worthless 2 cents..

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