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Kenwood TM-V7A head unit button issues

Discussion in 'General Technical Questions and Answers' started by KE8LUL, Apr 3, 2020.

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  1. KE8LUL

    KE8LUL Ham Member QRZ Page

    This past week I got in my car and I turned on the radio and went to change the VHF band that I was monitoring and the radio would not allow me to select that band it would only stay on UHF. So I tried to press some of the other buttons to see if they worked and none of the buttons on the control unit would work except the scroll wheel to change the memory channels on the UHF band. I did reset the radio hoping that would fix it but after that it is still not working. I am able to use the mic to change with band I am talking on but I can't get into the setting or anything on the radio from the mic. I did take it apart to see if there was any corrosion or if anything had burned up and the board looks clean and nothing seems out of the ordinary. If anyone has an suggestions or a way to fix it I would appreciate it.
     
  2. KA9JLM

    KA9JLM Ham Member QRZ Page

    Clean the control head connections with alcohol.
     
  3. KD0RCB

    KD0RCB Ham Member QRZ Page

    Yes, 1st clean/ reseat CN701 cable on control head...if that doesn't fix it, pin 3 on that cable switches UHF, pin 8 switches VHF, (to ground for both). Check these lines with an ohmmeter or scope,( power unhooked from radio). After that, both lines feed directly into IC4, microprocessor control. Randy.
     
  4. W4HWD

    W4HWD Platinum Subscriber Platinum Subscriber QRZ Page

    I bought my V7A from Burghardt’s circa 1996 - could age be a factor?
     
  5. KE8LUL

    KE8LUL Ham Member QRZ Page

    I tried cleaning it and it didn't work. I will test it and see what I get. I assumed it was an age issue. My father in law gave it to me because he no longer used it and t worked great until earlier this week. It might just be time for a new one
     
  6. KD0RCB

    KD0RCB Ham Member QRZ Page

    These are good radios, I have 2 of them...as I stated earlier, pin 3 should "ground itself"- (zero ohms with ohmmeter on ground), when UHF button is pushed, and pin 8 should ground for VHF button push. If resistance jumps around & acts fritzy, try spraying the 2 switches with a good cleaner like DeOxit, etc....Ive never had a micro go bad in these radios yet. Randy.
     
  7. KA9JLM

    KA9JLM Ham Member QRZ Page

    You may want to bring it inside, Try to dry it out in a dry environment. It could be a moisture problem.

    I put electronics in my oven with just the light turned on. It makes a nice drying box. Just remember it is in there before baking. :oops:
     

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