Kind of hard to tell, but this guy may have sort of as I think hes saying RGB worked, but didn't say if he put pin 7 of the CXA1145 to vcc to put composite into NTSC:
"I have acquired a PAL Turbografx.
Opening it reveals the same insides as the pictures above, I replaced the crystal with one of correct frequency for 60hz - I receive a black and white (NTSC?) picture over composite video.
I RGB modded the PAL Turbografx and I receive a colour picture over RGB.
So it seems this crystal is for PAL/NTSC only.
How may I set the PAL Turbografx to 60hz?
"
Looking at your thread, there may be a bit more to it though.