SBC6120 (a build-it-yourself PDP-8 clone) Last Buy and End ofLife

[Don Y]

Roger Merchberger wrote:
> Rumor has it that Jim Beacon may have mentioned these words:
> 
>> I'll also cite early double sided
>> boards, before through-hole plating - it is virtually impossible to 
>> solder
>> both sides of a socket.
> 
> Virtually impossible? I doubt that - however, there's a few caveats...
> 
> Why not get wire-wrap sockets that have longer tails, and put a 
> toothpick or popsicle stick under the socket when you solder it (with 
> enough room to remove it later), then it will give enough room to solder 
> the top as well, thereby bridging both layers. Sure, it's a little more 
> labor, but can & does work... Granted, if you were working in a very 
> limited height scenario, one might need to be careful with the extra 
> height.

That also is problematic if the devices are located too close
together.

*But*, you can buy individual *pins* and solder them as well.
E.g., consider how Augat panels are built...

>> Oh, and anything you want to be reliable......
>>
>> Remember all those "I reseated the chips in their sockets and it worked"
>> posts you've seen on this list!
> 
> Use machine-turned or machine-pin sockets. Don't blame the socket for 
> all the companies (CouATARIgh ;-) that used cheap sockets... Besides, 
> cheap sockets are still better than no sockets when you need to repair 
> or replace a ROM type chip (CouTANDYgh ;-) but I won't mention any 
> names. ;^>
> 
> Anyway, reseating chips isn't that difficult of a "fix" anyway...

Often, oxidation and corrosion (on a microscopic level)
are the culprit.  I've many older components with
"tarnished" pins (legs).  Even *soldering* to them is
a chore unless you remove the cruft.