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Mobile VHF radio problem

Discussion in 'Electronic Repair' started by Bob Engelhardt, Jul 15, 2003.

  1. I was checking a VHF boat radio for power polarity, using my car
    battery. Both polarities immediately blew the 10A in-line fuse. I had
    the radio sitting on the car and I realized that the heat sink was
    touching the sheet metal. The radio had worked before, so I assumed
    that it was the heat sink contact which had caused the fuse blows. The
    radio now shows a dead short between the input power leads.

    Questions:
    - could the heat sink contact damage circuitry? I would _think_ that if
    the heat sink was connected to anything it would be the power "neutral",
    directly, and not through any circuitry. Is it possible that it was
    connected through active circuitry?

    - if the heat sink contact did cause it, what is the likely extent of
    the damage? I.e., would it be worth fixing or is it likely trash? (It
    is a Standard Horizon radio - maybe $100 on eBay.)

    Thanks,
    Bob

    BTW - is there a better newsgroup to ask?
     
  2. Fast Eddy

    Fast Eddy Guest

    Look at the back of the set and locate the large power diode near to the
    power input wires.

    This usually shorts out.

    Desolder a leg off this diode and check it for a short. If it is replace it.

    You can run it without this "Reverse Protection Diode" but you will not get
    a second chance ever again.

    Other than that, I don't know


    PS Where can I buy Static Cleaner ??

    Edward B Tweedel
    Oxford
    UK
     
  3. Sofie

    Sofie Guest

    This is absolutely correct advice.....
    .... and as advised if the reverse polarity diode is shorted...... replace it
    immediately..... do use the radio without it.
    Certainly other parts could be faulty due to the shorted heatsink, but this
    is a good place to start.
     
  4. Ummm "do use the radio" ??? :)
    You have the same finger problem I am afflicted with !!
     
  5. That was it! Replaced it and it works! Thanks a million, as they used
    to say. I love newsgroups. Bob
     
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