[sdiy] TB-303 terror

[Byron G. Jacquot]

> I am working on this TB-303 that has a wierd issue. When I go into
> proram mode I can play any note from the keys, but when I play back
> from the memory, every note is one of the lowest 4 on the keyboard.
> Also slides and accents don't record, but octave up and down do.
> 
> Is there a bad memory chip? Has anyone had this problem? I have been
> running over and over it all day.

That's an 8-bit RAM chip, right?  Check the data outputs from it with 
a scope probe, while playing back.  You might also watch the !RE 
line(s) to it, as well as the address lines.

If it's two 4-bit RAMs, then there may be a problem in decoding the 
even/odd addresses, or one of the chips has gone bad.

IF it's like the TR606, with 2 4-bitters, you could try swapping the 
RAMs with each other and see if the problem moves with 'em.

Byron Jacquot