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Inherent Problem with Yaesu MH-27 Microphone

Discussion in 'General Technical Questions and Answers' started by KX0Z, Nov 11, 2009.

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  1. KX0Z

    KX0Z Ham Member QRZ Page

    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. ZL1UZM

    ZL1UZM Ham Member QRZ Page

    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. W9GB

    W9GB Ham Member QRZ Page

    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 ! Mod.pdf

    HERE are the MH-27 NOTES from Tim Landers, N4HIG

    PHOTOS of MH-27 repairs

  4. KX0Z

    KX0Z Ham Member QRZ Page

    Thank you, that exactly the information I was looking for. Just couldnt remember who had it..
  5. AI3V

    AI3V Ham Member QRZ Page

  6. W9GB

    W9GB Ham Member QRZ Page

    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.
    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.

    Last edited: Nov 11, 2009
  7. AI3V

    AI3V Ham Member QRZ Page

    Not a chance that all 3 of those parts failed.

    I'll put money on it:D

    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.

  8. AI3V

    AI3V Ham Member QRZ Page

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

  9. KX0Z

    KX0Z Ham Member QRZ Page

    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. KX0Z

    KX0Z Ham Member QRZ Page

    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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