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Re: [softrock40] Re: RXTX Ensemble TX OpAmps Question

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  • Alan
    ... Subject: [softrock40] Re: RXTX Ensemble TX OpAmps Question ... So the 5V line is still 4V4? The voltage across R52 is consistent with 90mA drawn from the
    Message 1 of 8 , Nov 2, 2012
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      ----- Original Message -----
      Subject: [softrock40] Re: RXTX Ensemble TX OpAmps Question


      >I lifted pin 8 on U7 and found that all of the voltages went back to specification. I ordered a new Opamp from Mouser and replaced
      >the part. I then got the 2.15V on pins 6 and 7 of U7 (where I was getting nothing previously), but the voltage is still being
      >pulled down and my current still reads above 90mA. Rechecking components along the 5V power line I cannot find any obvious
      >problems to cause the increased current and decreased voltage. Though I am continuing to investigate, are there any further
      >suggestions for tracking the down the culprit?

      So the 5V line is still 4V4?
      The voltage across R52 is consistent with 90mA drawn from the 5V line.
      Measure the resistance from the 5V line to ground with no power. I'd guess this should not be less than about 1K.
      If it is less look at your resistor values.
      If it is more then check all voltages bearing in mind they will likely be proportionally lower than nominal.
      If nothing obvious shows up try lifting the pins giving 5V power to each of the ICs as you did on U7.

      Hopefully that should give us something to work with.

      73 Alan G4ZFQ
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