multi-layer circuit boards

________________________________ From: Chuck Guzis <cclist at sydex.com> Hold the PCB up to a very strong light--many if not most multi-layer PCBs have internal power or ground planes.? This makes the PCBs pretty much opaque--you can't see light shining through where the top and bottom foil has been edched away.? Vias that seeming disappear into the PCB (i.e. no via visiable on the other side) are a pretty good hint also. --Chuck C: Thanks for the the input from you, Ryan, and Dave? ?My friend Yogi is going to scope this situation out for me. As I said, he seemingly has complete sets/s of APC documentation. If I could only convince more people that digital camera "scans" of vintage documentation are more then adequate, we might have a lot of this stuff archived already. But then idiots like me allow disk media to sit around too long and in the wrong storage conditions that it negates any benefit there is to having the documentation. What a shame.