Most of this is information on how to do stuff or ideas I had about how to do stuff because there was literally nothing better to do.

Service Manuals I have had to track down
Sansui QRX-7500, schematics only
Radio Shack / Realistic DX-390 (I think this came from mods.dk, screw those guys)
Tascam 488 (Mk1) Service Manual (scanned by me, I have no idea how to make a PDF)
Yamaha PSS-460 (scanned by me)
Akai GX-630D-SS schematic (thanks to DanielF on Audiokarma)
Akai GX-630DB service manual (ditto)
Akai AX-60 service manual

Sansui QS or Dolby Pro-Logic II 4:2 matrix encoder: Yo

What the trimpots do in a Pioneer RT-701: This
(record level, replay level, etc.)

What the trimpots do in a Yamaha YC-20 combo organ: This
(awesome, you need one, it's like a Vox and a Farfisa in the same box)

How to synchronize a Super-8 projector to your video camera for telecine purposes (No flickering, no blended frames): page 1 page 2
(I should convert this to HTML but I'm not going to because I hate computer. Drew up these plans for a Romanian dude)
Directly applicable to Chinon Sound 7800, 7500. Probably most electronically governed sound projectors.

How to get at the regular old animated-GIF NOAA radar: Replace GRK with your weather station