Not sure if this is the right place to post this question...
I repair a lot of old electronics, many of which are one of a kind. As a result, I've spent many years obtaining rare service manuals that appear to be unavailable anywhere else.
I'd like to start archiving a number of these service manuals to the Internet Archive but, while scanning a normal sheet of paper is quite simple, many have large fold out schematics that just wont fit even a large format flatbed scanner like the Epson 10000XL or similar. Most will be scanned as B&W, some have gray-scale oscilloscope images, and, I mean, I wouldn't mind color support for posters or other large promotional artwork I have.
One option is to use a camera and flat surface, but I really don't believe the image quality is acceptable for something like a schematic. It is extremely important to make out relatively-fine non-text details of complex circuit diagrams or the schematic may be useless or misread.
I've read about large format scanners by companies like Contex and WideTEK, but they're so niche, I can't really find detailed 3rd party reviews about them... They're also really expensive since they seem to be self-contained computers? Does that imply they're worth my money?
Could there be other options that I don't know about?
So I guess my question is two-fold... What is the best large format scanner technology for scanning a large, fold-out schematic and what would be an appropriate (the best) large format scanner model(s) for my needs?