I have what should be a schematic file from a vendor, its suffix is .sch. I tried opening it with Eagle CAD but it wouldn't open. I then looked at the file with a text editor and there seem to be some references to Orcad.
Does anyone know if .sch files are Orcad files, and if so where to get a free viewer program from?
Orcad, PADS and Protel all used .sch at one point and there is no standard implied with the file type. Orcad now uses .DSN. Check with the vendor. Most commercial products offer a free reader (aka viewer) or a free Lite version that limits modification but not the open, so users can view files.