[sdiy] stuck on TR-909 hats repair

[Colin f]

> In the circuit pre D/A, I've replaced all the IC's (except 
> for the rom), replaced all the transistors, and tested all 
> the caps, diodes, and resistors.  Aside from replacing the 
> rom I don't know what to do next.

Next thing to do would be to try replacing the ROM.
A tricky proposition, since the 909 ROMs are mask-programmed, and use a
non-JEDEC standard pinout.
Two pins need swapped over, and IIRC the CE line is active high on the hats
rather than active low.

Cheers,
Colin f