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  1. #1

    Garmin VHF power issue

    Hey all, I have a Garmin VHF in my boat that has been working fine thus far. I last used the boat and have traced an issue back to it. When connected to power it is blowing fuses instantly. I have removed it from the boat and when the power wires are connect directly to battery posts it shoots out sparks and just can't be connected. Any ideas?
    Cheers

  2. #2

    Re: Garmin VHF power issue

    Most radios use diode protection as a means of preventing further damage (by blowing the fuse - hooking up direct to a battery if something is blowing a fuse isn't a great idea) The diode will typically fail if a reverse polarity condition has been present (even for a split second) and in most sets if an over voltage condition has been present (same deal with the the time frame). When the diode fails it creates a short circuit across the power input which causes the fuse (and any subsequent fuses until the diode is replaced) to blow. Hooking the radio directly to the battery without a fuse while in this condition can cause the printed circuit board to be damaged if it is the "next weakest" current carrying device.
    "I soak the worms in rum. The fish love em and the worms die happy"
    "Alcohol is not the solution to your problems...................but then again, neither is milk"

  3. #3

    Re: Garmin VHF power issue

    Cheers Scottar, it was fused when connected straight to battery. Thanks for your reply.

  4. #4

    Re: Garmin VHF power issue

    Shorted diode would be same as a working diode provided polarity correct tho? Unless it was a zener that gave overvoltage protection. Even then I would think no difference. Anyways Scrotty - she's stuffed mate. They don't repair these things - buy another.
    Not trying to be a smartarse Scottar; always happy to be re-edumucated if I am wrong.

    Sent from my SM-G900I using Tapatalk

  5. #5

    Re: Garmin VHF power issue

    Quote Originally Posted by TheRealPoMo View Post
    Shorted diode would be same as a working diode provided polarity correct tho? Unless it was a zener that gave overvoltage protection. Even then I would think no difference. Anyways Scrotty - she's stuffed mate. They don't repair these things - buy another.
    Not trying to be a smartarse Scottar; always happy to be re-edumucated if I am wrong.

    Sent from my SM-G900I using Tapatalk
    They aren't in series - they are put across the inputs to complete a circuit in a reverse polarity situation and thus create a short to blow the fuse. In the process they usually destroy themselves though. If it is just a polarity diode and someone has any sort of soldering skills it's not a huge job. We did repair them when I was at Trymax - cheaper than a new one if that's all that was wrong. Give the boys a call - at least worth asking.
    "I soak the worms in rum. The fish love em and the worms die happy"
    "Alcohol is not the solution to your problems...................but then again, neither is milk"

  6. #6

    Re: Garmin VHF power issue

    I'm pretty handy with most things so I opened it up to have a look. I can't see anything obvious to me but I really don't know what the damaged diode would look like anyway? Might just do the modern thing and throw it away and buy a new one?
    Cheers for info guys.

  7. #7

    Re: Garmin VHF power issue

    Quote Originally Posted by scottar View Post
    They aren't in series - they are put across the inputs to complete a circuit in a reverse polarity situation and thus create a short to blow the fuse. In the process they usually destroy themselves though. If it is just a polarity diode and someone has any sort of soldering skills it's not a huge job. We did repair them when I was at Trymax - cheaper than a new one if that's all that was wrong. Give the boys a call - at least worth asking.
    Thanks Scottar, makes sense.

    Sent from my SM-G900I using Tapatalk

  8. #8

    Re: Garmin VHF power issue

    My diode leaks and get this, it's before the on/off switch on the radio so I have to disconnect the battery or it will go flat in a Month or so.
    Having said that scrotty, try connecting the radio with the switch turned off and if it still blows a fuse my money is on the diode being short circuited... SNIP!

  9. #9

    Re: Garmin VHF power issue

    Hey Fed, yeah she still blows. I would replace the diode but I don't know which one it is? Cheers

  10. #10

    Re: Garmin VHF power issue

    Quote Originally Posted by Fed View Post
    My diode leaks and get this, it's before the on/off switch on the radio so I have to disconnect the battery or it will go flat in a Month or so.
    Having said that scrotty, try connecting the radio with the switch turned off and if it still blows a fuse my money is on the diode being short circuited... SNIP!
    Before the switch is normal for radios at least Fed. Can't ever recall seeing anything different.
    "I soak the worms in rum. The fish love em and the worms die happy"
    "Alcohol is not the solution to your problems...................but then again, neither is milk"

  11. #11

    Re: Garmin VHF power issue

    I don't do radios scottar they work on magic IMO.

    I would replace the diode but I don't know which one it is?
    It would have to be between the power socket & the on/off switch scrotty, wired straight across the positive & negative. I don't think you would have to replace it, just cut it out, scottar?

  12. #12

    Re: Garmin VHF power issue

    There is a little blue barrel looking thing soldered across the positive and negative where the power lead is soldered to the board?

  13. #13

    Re: Garmin VHF power issue

    It will work without it but is probably a zenor for overvoltage protection as well and really should be replaced.
    "I soak the worms in rum. The fish love em and the worms die happy"
    "Alcohol is not the solution to your problems...................but then again, neither is milk"

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