On Tue, January 19, 2016 5:29 pm, J Martin Rushton wrote:
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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 ++++++++++++++++++++++++++++++++++++++++