ICOM Mic Wiring:

Discussion in 'General Technical Questions and Answers' started by K5RCD, Oct 9, 2008.

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  1. K5RCD

    K5RCD XML Subscriber QRZ Page

    I have an ICOM 706 MK2 G with the factory HM-103 microphone.

    The 8 pin modular RJ45 male connector on the end of the mic cable has become damaged.

    I have some RJ45 connectors and a crimping tool, so I thought replacing it would be a simple matter of looking at the wire colors in the old RJ45 and just stripping the cable and wiring it the same. WRONG !

    The colors in the connector do not match those inside the cable. There must be a transition which I destroyed during stripping just inside the cable, because when I cut off the connector and stripped the wire I got a big surprise.

    Using a jewelers loupe, the colors visible in the RJ45 are as follows:

    Pin1 = empty
    Pin2 = black
    Pin3 = empty
    Pin4 = green
    Pin 5 = Either dark brown or black (my old eyes cannot tell)
    Pin 6 =white
    Pin7 = blue
    Pin8 =empty.

    When I look at the stripped wire I see only the following colors: black, green, white, blue, red. there are also two non insulated stranded wires, one copper colored and one silver colored. Those two look like they might be shielding of some sort but I cannot tell without further stripping the wire to the point it will be too short to be useful.

    In stripping the wire, it looks to me like the red wire simply ended inside the bundle without actually being connected to anything, and the two non insulated wires also were not connected to anything. No red or non insulated wires appear in the RJ45 connector.

    I know where the white, blue, and green wires go in the connector, but am not positive about the black wire (is it really black, and the only black wire?). That also leaves me one wire short in the bundle assuming the red wire didn't change to brown inside the bundle.

    I have no schematic or wiring diagram, and the Instruction manual is no help.

    Does anyone have a color coded diagram or know what is going on here ?

    Help Mr.Wizard ! :confused:
  2. N8LES

    N8LES Ham Member QRZ Page

  3. AB8ZL

    AB8ZL Ham Member QRZ Page

    It sounds like you pulled some wires out of the RJ45 connecter when it became damaged as all eight pins are used.

    If it was pulled on enough, some of the wires may have broken inside of the cord.

    The manual shows the following connections (but no color codes).
    1. +8 volts dc output
    2. Frequency up/down
    3. AF output
    4. PTT
    5. Microphone ground
    6. Microphone input
    7. Ground
    8. Squelch

    I have an IC-7000 and while it doesn’t come with the HM-103 Mic, it is compatible with it. The only difference in wiring according to my manual between Mics (the HM-151 and HM-103) is pin eight. On the HM-151 pin eight is a data line instead of squelch.
    The colors of my connections are (as best as my eyes can see)
    1. Red
    2. Brown
    3. Yellow
    4. Green
    5. Bare stranded wire
    6. White
    7. Blue
    8. Black

    It’s strange that Icom doesn’t show the colors for the Mic wiring in ether manual but I hope this information can help.

    P.S. I have tried a standard computer CAT 5 cable on my radio and it worked just fine.
  4. W9GB

    W9GB Ham Member QRZ Page

    Japanese manufacturers DID NOT follow the conventions of earlier American microphone manufacturers (e.g. Astatic, Turner, Shure) in using specific colors for specific microphone functions (e.g. mic audio, ground, PTT).

    SO, this means you may have identical microphones, but with different suppliers -- and hence -- potentially different wire colors.

    ALWAYS use a DVM or VOM to verify wire function -- OR open up the microphone and trace by color.

  5. AB8ZL

    AB8ZL Ham Member QRZ Page

    I just thought to add that you could check the other side of your cord if it isn’t hard wired into the Mic or radio. The color order should be the same.
  6. WA6ATI

    WA6ATI Ham Member QRZ Page

    Heck: I thought that the Japanese manufactures had a more diabolical plan. They don't want you to fix it, they to sell you a new one. I'm right in the middle of doing one of these RJ45 installs.

    Dennis V.
  7. W9GB

    W9GB Ham Member QRZ Page

    Actually, some of that has to do with the changes in electronics technology.

    However, lest we forget that it was also used by the American automotive mfg. (1970s and 1980s) --
    they followed that mantra before the electronic industry adopted it.
    Today, the new GM chairman began a series of commercials to change their image -- that this approach created!

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