Hi!
Stumbled across this forum via googeling after this part.
I also already learned the lesson for adding 2S for japanese parts, so I successfully found 2SD1047/2SB817
But I got stuck with "C6391" or "C63918" (not quite clear) There also is "PH 08" on the package just below the C number.
It's a three pin package like BC547 but beeing a bit longer with the "black part".
It died in a Proton power amp, where it sticks quite close to a 1E resistor and the power transistors, when one channel got killed by shortening speaker cables.
Anyone got an idea with what to replace this?