wiretap wrote on 2021-09-09, 16:52:
99%+ of ISA slots you'll be putting an Adlib in will have phosphor bronze mating pins. It is corrosion/oxidation tolerant to lead and tin -- of course tin because it is partly made of tin itself. Also, lead is often melted in with it on purpose to give it better casting ability and flexible properties. Many early ISA cards had tin/lead edge connector fingers.. I have several in my collection, and I still have many in service at work with 30 years of runtime on them.
I have never seen problems with HASP slot fingers, too. They were really common back then.
Well, the only problem is the oxidation which can also be seen in the OP's photo. But that can be wiped of using vinegar.
wiretap wrote on 2021-09-09, 16:52:
I've never seen gold plated ISA slot contacts on any motherboards I own. That would have been a special order item of the era, or only used in high end industrial boards requiring precision contact/connection for signal integrity. When ordering new parts from Tyco, TE Connectivity, etc - it is now common to see gold plated contacts in ISA slots since it costs far less to manufacture today.
Maybe because of ROHS?
The ISA slots in my 2016 LGA1150 industrial mobo of my new DOS gaming build are indeed different than those I am used from old consumer mobos.
Much better grip, maybe indeed harder metal. Will examine them more thoroughly soon.
maxtherabbit wrote on 2021-09-09, 14:28:
this is false, an unbeveled card edge will wear down any card slot, ISA or otherwise
True... a card with burrs is cruel to the slot, like a scraper.
Just do some careful work using a fine file to remove and round off the burrs so that the card slides into the slot smoothly.
BTW, back in Apple II times when I etched my own boards, I manually soldered on tin plating to prevent the copper corrode. This was far thicker than electrolytic plating and indeed the slot got somewhat "dirty" over time after many plugs/pulls.