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Was Working - Died

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  • Mike Saeger
    I went on a 1 week trip forgetting to turn the Softrock off. Came back and it was dead. I checked S12V and it was just over 6V on RX. Goes up to around 8V on
    Message 1 of 2 , Apr 11, 2013
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      I went on a 1 week trip forgetting to turn the Softrock off. Came back and it was dead.

      I checked S12V and it was just over 6V on RX. Goes up to around 8V on TX.

      I replaced Q3 because it was VERY HOT. New one also gets VERY HOT on just on Rx.

      Apparently, something happened to the switching circuit.

      I'm getting the 11.64 volts at the base of Q3 (with Q3 disconnected)

      Voltage at pin #4 of U4 is around 6.09V (Q3 disconnected) diagram says it should be over 9V.

      With Q3 disconnected, total current draw is around 30ma. With Q3 connected it zooms up to over 100 ma on RX and on TX it exceeded 250 ma with no drive.

      When it was working S12V was almost 12V and about 0V on RX.

      I admit I really don't understand FETs and don't know how to check them. There are several of those BS170s.

      Any ideas on what I can check before I give up? It was so much fun using that radio -- I'd hate to have to toss it out. I tried searching for SoftRock repair but it looks like if i can't fix it I'll have to toss it out.

      Mike N9MS
    • Alan
      ... Subject: [softrock40] Was Working - Died ... Mike, What is your actual voltage on the 12V line? ... Under these conditions, voltage on 12V line? Other U4
      Message 2 of 2 , Apr 11, 2013
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        ----- Original Message -----
        Subject: [softrock40] Was Working - Died


        >I went on a 1 week trip forgetting to turn the Softrock off. Came back and it was dead.
        >
        > I checked S12V and it was just over 6V on RX. Goes up to around 8V on TX.
        >
        > I replaced Q3 because it was VERY HOT. New one also gets VERY HOT on just on Rx.
        >
        > Apparently, something happened to the switching circuit.
        >
        > I'm getting the 11.64 volts at the base of Q3 (with Q3 disconnected)

        Mike,

        What is your actual voltage on the 12V line?

        >
        > Voltage at pin #4 of U4 is around 6.09V (Q3 disconnected) diagram says it should be over 9V.

        Under these conditions, voltage on 12V line? Other U4 voltages?

        >
        > With Q3 disconnected, total current draw is around 30ma. With Q3 connected it zooms up to over 100 ma on RX and on TX it exceeded
        > 250 ma with no drive.
        >
        > When it was working S12V was almost 12V and about 0V on RX.

        Resistance to ground at S12V? Not powered.

        Mike
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