Quoted from LateCenturyMods:
Pretty sure that's all they give you, yes.
Music is generated by the YM2151 and the YM3012 is your DAC. If you have an oscilloscope, you should be able to see clock and data out of the YM2151. I've heard of failures of the YM3012 and the MC1458s, and associated discrete items like capacitors.
Thank you. This area is where I am focusing my efforts. I was thinking it was the 1408. But I’m now leaning more towards the 3012 or some of the discrete circuitry in between. I replaced the 2151 with another one I had but not totally sure it is good. But it didn’t change anything either. I replaced the op amp at u12. And ordered new 2151 and 3012 as well as the 1408. I replaced the cap at c3 and c2. C3 looked swollen. I have c4-6 and may just replace them as I know it’s past time for them. I found this other post from a few months back about Pinbot with no speech. The write up below by kbliznick is pure gold!!! Here is a quote from him on one of the post. It goes thru every situation but mine. The last one. No music but speech and sound.
Best advice would be to remove the ribbon cable from the sound board to the cpu board. Then go into the sound test though the diagnostic menu and see if the game makes any sounds. If it makes some sound effects but no speech then it's the 3 likely components on the mpu board. If if makes no sound at all then it's the slightly harder repair on the MPU board. Double check your work by reattaching the ribbon cable and rerunning the tests. If this is a standard build pinbot the music will be all that is generated on the background sound board through the ribbon cable (and that can be tested in the music test) and all game play sound effects and speech will be generated on the MPU board.
order of likelihood for the no speech but sound effect result
1458 Op amp at U4
CVSD at U3
10 uf cap at C15
but the cvsd is the most $ and hardest to find part so swap that last.
order of likelihood for the no speech and no sound effect result
Bad 1458 Op amp at U5
Bad RAM on CPU sound section U23
Bad ROM's at U21, U22
Bad CPU at CPU sound section U24
3 wire cable missing between sound board and cpu board