Personally I cannot repair stuff working with schematics on pc screens.
I can only use bits of paper where a physical magnifying glass actually
works, unlike the usual PDF/virtual, joke magnifying glasses.
Other than magnifying the perfectly readable pc image before printing off on
laser printer,is there any other way of getting a printed image to be as
(almost) clear as the PC screen image ?
Say a schematic original is 4 A4 sheets then scanned in 1 to 1 (about, so to
allow some overlap) , in 4 sections, it needs printing off on 16 sheets to
get anywhere near to the original in resolution. Assuming a decent GIF image
rather than the usual joke PDF, better-than-nothing, stuff.

Update on previous thread on copying old brown paper schematics, the simple
way to increase the contrast was to scan in and just select "reduce colour
depth" in viewer, to just 2 colours and save as .gif , but then comes the
usual printing off problem.

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Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/