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Ranger 6900 board 8 v regulator.

Discussion in 'CB and Export Equipment and Accessories' started by nbsr, Dec 2, 2019.

  1. nbsr

    nbsr 327 Empire State

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    What is the purpose of putting the 8 v regulator in this way? Seems like wanting to cause a problem or i am obviously missing something? IMG_0794.jpeg


     

  2. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    Looks like someone substituted a different transistor and did this so the legs go to the right place.
     
  3. nomadradio

    nomadradio Analog Retentive

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    Have a look at the number on that, er, "transistor".

    I'll guess that it shows something like "7808" or "7809", or "78M09".

    Or maybe "LM340".

    More than once when the two-transistor regulator fails in a radio with a EPT6900 pc board we save the labor of fixing the original circuit by bolting in a one-piece 3-terminal regulator. Looks like a transistor until you read the type number.

    Does the same job, and also has a current limit built into it. Fooling around with the echo board, or taking loose a board bolted to the side rail can short the 9-Volt supply to ground and blow out the factory regulator.

    It's a PITA to troubleshoot the factory circuit, but the 3-terminal part will fix the problem quickly and be more reliable in the long run.

    Pinout of the new regulator chip calls for some "crossed legs" to get the proper hookup.

    73
     
    #3 nomadradio, Dec 4, 2019
    Last edited: Dec 4, 2019
    Shadetree Mechanic and Robb like this.
  4. nbsr

    nbsr 327 Empire State

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    Thanks for your input. I knee-jerk reacted and ASSumed it was an 1869. Blowing up the pic and then looking at it under a glass, yeah I'm old, it is a 17808T. Q35, D73 and R 214 were never installed in the board, so get ready for multiple questions.
    1. This was from the factory?
    2. When replacing Q37 or T41 is this the way to go?
    3. Is there something better?

    I would prefer to always to make better, so your advise will not fall on deaf ears.
     
    Shadetree Mechanic likes this.

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