YouTube
All of my YouTube-related downloads, diagrams, schematics, etc live here. I will never charge for my knowledge, so download away.
Here are the Tascam 388 schematics that I captured from the original service manual. This is a single download containing all 18 schematics packaged in a single zip file. This is free. If anyone is trying to charge money for this file, they stole it from me and they suck.