Yep It’s Got Voltage!

Carl from the UK messaged me last night about the President Mc Kinley and whether it had voltage on any of the microphone pins. Then this morning 09.30 an email came in (from another person) asking me what would make smoke come from the microphone socket on a President Mc Kinley. Below is the wiring diagram from the manual of the Mc Kinley and YES it has voltage from Pin6. Amongst other things it drives the Electret and also adds power to Liberty mike.

Update:

After the smoke the radio has no transmitted audio

He touched the 6 pin with another and shorted out the plug

Could be a resistor behind the microphone socket

Arranged the radio go for repair and it leaves for repair at cost this morning!

So, no radio catching fire. Was a mistake from the owner which he’s upset about. Radio is as explained now away for repair. The operator was in Germany!

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8 thoughts on “Yep It’s Got Voltage!

  1. Pretty simply put Simon 🙂
    Dont fiddle or better just leave along and use stock fist mic should be more than sensitive enough.
    turn electret voltage off via menu so no chance of shorting it out if option available
    Dont work and wire stuff on live cb your asking for trouble,study first wiring and double check work as its very easy to muck up on pin wiring even on land mobile radios, its same, so do not blame President at all and def not a Lincoln 2,this purely user error at work here!
    and a silly mistake made,it happens more so with new radios now have various voltages running up and down microphone leads and some with tx \rx data pins can easily be shorted out by mistake on multi pole plugs\socket types.

    You have to pay real attention to detail and not second guess with these new radios and electret mics,on some CB & LMR mobile radios,some you cannot turn off electret voltages,so have be extra careful when interfacing new things to radio’s especially dynamic microphones or amplified microphones (not really needed anymore)or interface audio cables,some may require a blocking capacitor to stop DC on mic live input.some do it different methods.
    If your not sure leave well alone and get expert advice or email GPE technical directly we not living in dark ages anymore.

    Ive seen service radio engineers make worst mistakes than this, having been and worked in the 2 way radio industry for a very long time.
    so lets stop now all the scare mongery nonsense of CB radios catching fire! and nip it in the bud!

    GPE are not at fault one bit,other manufactures use similar systems so this is not just unique to this brand of CB radio and that include business band professional radios too.

    Simple mistake….and nothing more than that.

    Hope the chap gets it fixed and back on air soon with new toy Simon,i bet his heart sank when it happened.
    A unfortunate costly mistake,but it does happen and a valuable lesson learnt in engineering.

    I hope other Users take note from this and new equipment….cb or other..

    73’s Rob

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  2. Ok Simon, it just wasn’t clear to me from your post what had happened.

    The last thing President need is another Lincoln 2 situation with problematic radios. Good to know this isn’t the case.

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    • The article is now updated.

      He shorted the hot wire with another and it caused in my opinion the resistor behind the microphone socket to burn hence the smell. This always results in NO transmitted audio.

      Yesterday afternoon I’ve arranged for the radio to be repaired. He pays all costs as no warranty for export mode radios and clumsiness. The owner is in Germany and will have the radio repaired also in Germany. It was a genuine accident from someone wiring a microphone and not taking care and never looked at the wiring diagram which is in the manual also.

      €330 radio €17 to receive it and lasts 2 hours and fried it. Very sad indeed but a lesson for one and all from this that is certain.

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    • A: It wasn’t Carl

      B: The guy touched something while wiring the microphone and f’ed it up which he’s admitted

      C: Nothing dodgy other than someone didn’t look at the diagram and wasn’t careful enough.

      So don’t fake news stuff!! It was the mistake of someone who didn’t know better and already the radio is gone (this morning) for repair.

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  3. Morning Simon would it be possible for an astatic d104 to be wired up to work with a McKinley or would be done by knights

    Carl

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    • Hi Carl.

      I’d get the dealer to look at it to be fair but saying that I’ve tried the following

      Astatic Teardrop
      RF Limited Xtreme 2018
      Sadelta MB-4 Plus
      Turner +3B
      Astatic Road Devil
      Stabo Optimike
      RF Limited CR-577

      Plus Robert another guy here has tried others microphones and we’ve all the same ending at the moment that the standard microphone has sounded the best at the moment.

      Regards
      🧙‍♀️

      Like

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