On Tue, January 19, 2016 5:29 pm, J Martin Rushton wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> I suspect that the gold layer on edge connectors 30-odd years ago was
> a lot thicker than on modern cards.
I remember a long time ago - that actually was in the country "Far -Far
Away" ;-) We were not allowed to dispose of connectors with gold plated
contacts. These were collected, and gold was extracted from them and
re-used. I believe, there were dissolving base brass material with acid,
then just melted the thin gold shells left. Not useful with modern super
thin plating.
> We are talking contacts on 0.1"
> spacing not some modern 1/10 of a knat's whisker. (Off topic) I also
> remember seeing engineers determine which memory chip was at fault and
> replacing the chip using a soldering iron. Try that on a DIMM!
>
> On 19/01/16 00:39, Peter wrote:
>> On 19/01/16 12:34, J Martin Rushton wrote:
>>> Not new: I can remember seeing DEC engineers cleaning up the
>>> contacts on memory boards for a VAX 11/782 with a pencil eraser
>>> c.1985. It's still a pretty standard first fix to reseat a card
>>> or connector.
>>
>> I used to do that as well. The contacts would come out nice and
>> shiny when you clean them. Then I found out that what I was
>> actually doing was removing the very thin layer of gold plating on
>> the contacts and revealing the copper underneath. That's why you
>> should never clean contacts with a pencil eraser, just re-seat the
>> boards and they'll make contact again.
>>
++++++++++++++++++++++++++++++++++++++++
Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247
++++++++++++++++++++++++++++++++++++++++
_______________________________________________
CentOS mailing list
CentOS@xxxxxxxxxx
https://lists.centos.org/mailman/listinfo/centos
