[sdiy] black flaky chip legs: what does this indicate?

[chris]

On Sun, 1 Nov 2020 22:26:47 +0000 Kenny Balys <kenny at beatkamp.com> wrote:
> So this is related to faulty componentry and not mysterious
> acid clouds forming in synthesizers then?

So the lesson is: don't play acid songs on machines not designed for
that style.
There's a reason that Texas Instruments never did a 303 clone.

Chris



> Yes!!!!!
> 
> They were both TI and the device was manufactured in 1979.
> 
> Both IC's were socketed. I had to pull disconnected legs out of the
> sockets after removing the chips. They shed their legs.
> 
> So this is related to faulty componentry and not mysterious
> acid clouds forming in synthesizers then?
> 
> 
> 
> On 01.11.20 22:12 , S Ridley wrote:
> > Were the blackened legs on Texas chips?   I've seen a lot of this on ICs from
> > the late 1970s or early 80s.
> >
> > I heard that Texas offered different grades of plating for ICs which were meant
> > to be soldered or socketed - less plating on the ones which were meant to be
> > soldered.  As these were cheaper...  well, guess the rest.   While I
> > can't confirm the story is true, it ties in with what I've seen.
> >
> >
> >
> > Steve
> >
> >
> >
> >
> >
> >
> > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>
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> >
> >
> >
> > On Sun, 1 Nov 2020 at 19:21, Kenny Balys <kenny at beatkamp.com
> > <mailto:kenny at beatkamp.com>> wrote:
> >
> >
> >     I completed a repair and had two 74LS138's with blackened
> >     legs. I went to pull one and it came apart. The legs are
> >     degraded somehow. Then on to the other 74LS138: same.
> >     The legs of the IC's just fell away.
> >
> >     What could have caused this?
> >     Has anyone seen something like this?
> >
> >     There is no Varta battery pack on the board. I have seen
> >     something like this on a Poly-Six.
> >
> >     Other IC's near these two were not the same. The circuit
> >     board seems to be ok.
> >
> >     The instrument is now functional after replacing the
> >     two 138's and changing a few caps.
> >
> >     Thanks in advance for any ideas.
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> >
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Christian