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9271Re: Softrock 40/80 debug

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  • tom_iphi
    Mar 1, 2007
    • 0 Attachment
      You just have to provide enough energy so the whisker evaporates at
      once. The professionals do it sometimes like this.
      --- In softrock40@yahoogroups.com, "pmartin45601" <martinpd@...>
      wrote:
      >
      > Then you'll have a carbon trace where the short was. Maybe not a
      > short but a resistance non-the-less. Probably not a good idea.
      > Paul
      >
      > --- In softrock40@yahoogroups.com, "tom_iphi" <iphi@> wrote:
      > >
      > > 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..)
      > > > >
      > > >
      > > >
      > > >
      > > >
      > > >
      > > >
      > > >
      > > >
      > > >
      > > >
      > > >
      > > >
      > > > 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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