I'm hoping someone with a real TB-303 can verify this for me. Most synths I've worked on have their tempco resistors thermally coupled to the expo converter, be it a chip or a transistor pair. In the copy of the TB-303 service manual I have, it shows the tempco running parallel to Q26 (2SC1583), but nothing is mentioned, or visible in the diagram, to indicate whether the resistor is simply board mounted, or on risers and coupled to the transistor with heatsink grease or a metal clip. It makes sense that it would be coupled to the transistor, but I'd like to know before I rig my x0x mainboard that way.
Oddly enough, my old Minitmoog (The "t" is not a typo) has one oscillator's tempco thermally coupled, while the other oscillator simply has its tempco board mounted about 10 millimeters away from the expo converter.
Don Taylor, a.k.a. Brassteacher
"Jack of all trades, master of none, proficient at even fewer..."