wrote:


No solder mask ? (that is what we call that **** here)


** Nothing, the copper tracks were tinned and left bare. Not uncommon in those days - ie the early 1980s.


With the cost of solder, most people figured out it was a good idea to use a solder mask, and this was true long time ago. Were they high or stupid ?
Or can you discern ANY logical reason they did this ?

** The reason is that were using old fashioned, manual PCB making methods -
when board patterns were laid out with black adhesive tape and pads on clear plastic.



.... Phil