You occasionally see a 'for parts' Apple ][ on eBay or other sites that is throwing up some garbage characters or graphics onto the screen. Is there a page or document that categorises these artifacts into possible points of failure? My machines are working at the moment but I feel like a handy reference guide could save me some trouble in the future.
I don't recall seeing anything like this in the Technical Reference Manual or elsewhere, but apologies if it's in an obvious place.
Well, this might not exactly be what you are searching for, but it helped me a lot!
http://www.appleii-box.de/H198HomeRepairGuide.htm
That looks pretty handy, thanks. Now I recall that there are several books from the 1980s about Apple II home repair, which might be useful compilations. I just assumed there would be a more complete guide out there on the Internet now, but I suspect it's more of a case-by-case diagnosis these days.