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Icom 706mkiig Will Not Turn On

Discussion in 'Ham Equipment' started by wcsd106, Aug 8, 2019.

  1. wcsd106

    wcsd106 Active Member

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    Good morning,

    Short Version (More detailed version below)


    Problem: Icom 706MKiiG will not turn on.

    Steps Taken So Far:

    • Verified that power cord works on my spare 706mkiig
    • Verified that the control head works on my spare 706mkiig
    • Tried working control head on dead radio
    • Opened case and verified fuse is good and voltage making it past fuse
    • Checked underneath PLL board for corrosion and cut trace(s) - Corrosion present, traces OK however
    Detailed Version:
    I've had an Icom 706MKiiG in my truck for the past 8 years or so. I haven't used it in the past couple of years, but it's still been there mounted safely under the rear seat with the remote cable running to the control head under the center of the dash.



    To make a long story short, I recently got a new truck and removed all my radio equipment and personal belongings out of my old truck yesterday. The reason I hadn't used the 706 in a long time was because a ground issue was keeping the radio from operating correctly. (Worked fine on RX, but the minute you tried to transmit i.e. draw more amperage.. the radio would freak out and lock up requiring you to remove the power cord and reset it.) I never got around to running a ground wire directly to the battery, just stopped using the radio.

    Yesterday afternoon when I got home, I put the radio on my bench to check it out and noticed that it will no longer power up at all. No sound of any relays, no nothing. Dead in the water.

    Now, I have another 706mk2g and I hooked it up using this same power cord and it works perfectly. I also removed the control head from the radio in question and it works fine on the other mk2g, so we can probably rule out problems with the control head.

    I opened the case, and I am getting 13.8v past the fuse, so it's good, but the radio still isn't turning on or even trying to. I've read multiple instances of the rubber insulators under the pll board eating away at the pll board to the point of chewing up a trace. I checked that yesterday and the traces are good. Verified with a magnifying lens and a multimeter.

    Not sure where else I can check and there doesn't seem to be a lot of folks working on the mk2g anymore as it is getting older.

    I'm hoping someone has some common areas for me to check and can help me get this rig back up and running.

    Thanks.
     

  2. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    I don't know anything about this radio, but I am tuned in to see what the fix is. Sounds like something is shorted like the final. And when keyed, it causes the voltage to drop and that is why it goes goofy. Just a guess.
     
  3. wcsd106

    wcsd106 Active Member

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    The going goofy was likely a bad ground for the power cord. It only did that in the truck. On the bench it worked correctly.

    Now it's simply not powering up at all. No relay clicks, no nothing.
     
  4. BJ radionut

    BJ radionut Supporting Member and 6m addict

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    http://www.sarts1.com/
    You might try calling MATT and ask him if he has time to chat.
    He is the best I know of when it comes to ICOM rigs.
    His service work is TOP NOTCH!!!
    All the Best
    Gary
     
  5. w9cll

    w9cll W9WDX Amateur Radio Club Member

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    The 706 is very sensitive to power and will not turn on if the voltage is too far above 12v or to far below it. It sounds like yo did a lot of testing and my gut feeling it's dead. Sad part of the is parts are not readily available anymore.
     
  6. nomadradio

    nomadradio Analog Retentive

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    Pretty sure the power button is not a traditional switch mechanism in line with actual power supply.

    It's a command input to a microprocessor. If it boots up, it turns on the main power relay.

    Pretty sure. You did hear a slightly-delayed "click" from inside when it would power up, didn't you?

    If the microcontroller chip is not running its program, no power up.

    Found an article on mods.dk about the 706 restarting spuriously. He cleaned/tightened the radio's internal coax and flat-cable connections.

    Can't post a direct link to it, unless you're signed in to mods.dk.

    But that's the gist. A look at their list of 'mod' articles shows one about "restart". That's the one.

    Cheapest thing to try first.

    73
     
  7. wcsd106

    wcsd106 Active Member

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    Thanks, Nomad.

    In actuality, no I'm not hearing the faint relay click that should occur when power is applied.
     
  8. nomadradio

    nomadradio Analog Retentive

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    Not good. Either the relay itself is bad, or the computer isn't telling it to turn on.

    Makes me wonder if you can reach the two wires that go to the power switch. If they are accessible, bridging across them with a screwdriver tip would tell you if the push button itself is failing to close a circuit.

    73
     
    Mudfoot and 2315 Robert like this.
  9. wcsd106

    wcsd106 Active Member

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    Nomad,

    I've tried two separate control heads, both of which work fine on my good 706mk2g... Leaning towards a bad relay.
     
  10. nomadradio

    nomadradio Analog Retentive

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    Also possible. And testable.

    Once you tear that deep into it.

    73
     

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