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

[Kenny Balys]

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
>
>
>
>
>
>
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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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