So I have a DuoDisk that was on the fritz that, through a comedy of repair mishaps, is nonfunctional at this point. I'm waiting on parts and I'm pretty sure I can fix it, but I've got some questions that I've not been able to answer through googling.
First, I have a -107 analog board. I know there's a schematic put there but I'm reasonably sure it's for the -101 or -102 board because it has the MC3469 write chip, whereas my -107 board has no specific write control chip. Best as I can tell, Apple reimplemented it themselves with other chips and components, I'm guessing as a cost-saving measure. My question is whether anyone has a schematic for the -107 board.
Second, probably applicable to all board revisions, is what the potentiometers on the board do and whether any component replacements will require adjustments. I'm particularly worried if they deal with the analog side of the MC3470 read amplifier (which I don't intend to replace). If they do require adjustment, does anyone know what the adjustment procedure is?
Third, probably related to the second point, does anyone know how to use the built-in test points? I'm sure they were used during quality control, and provide a means of verifying functionality. I'm curious if anyone knows what Apple's testing procedure and parameters were.
Finally, as you may know, the funny behavior of the MC3470 is apparently key to some copy protection schemes. And, as with many FDD-specific chips, it's no longer in production (yes, new old stock and NTE rebadged chips are still out there). I'm curious about what other chips or solutions are out there, particularly what clone drives used (I have seen at least one clone Disk ][ analog board that definitely didn't have a MC3470), and how they perform with that copy protection.
Thanks for any information you might be able to provide!