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9267Re: Softrock 40/80 debug

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  • tom_iphi
    Mar 1, 2007
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      How about this idea:
      apply a high enough voltage to the suspicious via and fuse out the
      connection.

      If you reduce the voltage this is also a neat method for finding
      shorts thru the voltage drop. Just need a voltmeter that can measure
      millivolts voltage drops.

      73, Tom DG8SAQ

      --- In softrock40@yahoogroups.com, richard <richard.bown@...> wrote:
      >
      > Michael Karliner wrote:
      > >
      > > I completed the build of my TXRX today, checked resistances and
      > > initial current drain which seem OK. Upon connecting up to my
      > > PC and Rocky, I'm getting faint signals, but they are symmetrical
      > > around the center frequency, and connecting headphones to output
      shows
      > > that I've got no signal on the tip side.
      > > Unfortunately, I have not much in the way of test gear at the
      > > moment, although I'm trying to borrow a scope.
      > >
      > > Any words of wisdom or suggestions for debugging?
      > >
      > > Thanks in advance Mike (G8LKD, when I get this working..)
      > >
      >
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      >
      > Here's an unusual way finding dry/unsoldered joints on surface
      mount ICs
      >
      > Get yourself a 5 cms hypodermic needle, I find the green ones are
      best,
      > and holding the plastic end
      > gently run the point along the length of the IC over each pin. When
      you
      > go over a dry or unsoldedred joint
      > you will hear the note change.
      > so on a chip with 8 pins each side , on a good one you will hear
      ping
      > ,ping ping, ect 8 times,
      > as you find one thats dry the ping will sound much lower.
      > You cant do it with a solid needle it needs to be hollow to work,
      and
      > being made of stainless steel
      > you can always use the tip , made into a little hook to lift a leg
      of an
      > IC for test purposes.
      >
      > Even a solder bridge between pins is enough to change the resonance
      as
      > you go over it.
      >
      > HTH
      > Richard
      >
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