I also have a PinBot and when I got it the music and some background sounds were not present. I searched every topic and not really ever finding the smoking gun answer, as some issues with sound were not like what I had. See, when I was sure I found the same issue with speech working and music not and part of some sounds did and some did not, I was going to tell the world. Perhaps what I did learn will help you with sorting things out. First PinBot has some earlier sound boards in some games and sound issues seem to be an issue be it minor or hard to figure , they are common. Part of the sounds are generated on the sound board or card what ever reference you use, then go to the CPU to be amplified then returned to the sound board for mixing and delivery. In my case the speech was fine in every aspect. Speech and some sounds comes from the MPU board sound section and yes
the speech rom(s)s also contain some sound effects.
There is a way to test this with the white button on the MPU (read up
in the pinrepair site)
You should hear 2 tones. If you don't hear either tone then the
problem can be with the CPU, PIA or RAM for the MPU based sound
section. If you hear 1 tone, then the speech chip (55536) or the op
amps (1458) are bad. If the board has had battery damage it should only effect the background music and sounds
generated on the remote sound board. The controls for that board come
from PIA U41 and U42 which are located directly below the battery. This all of course is assuming you did the obvious ribbon cable switch and the connecters and such were checked. It seemed that a lot of the issues were fixed by replacing or repairing bad connecters.
I was lucky enough to be able to try a good sound board I put new chips in and the issue was still present. I narrowed it down to the CPU.Oh, and as far as the board. The board you have (system11) is the most interchangeable of all, for the era, It is a valuable board because it is the only board that those few game can use (High Speed is one of them ,Road Kings and Grand Lizard I think) system 11 A or 11B will also work for PinBot if D-11581 sound board is used with it.
I will leave you with this last check.to try. Good luck, and do not put a Rottendog Board in a PinBot. It takes a special pot and in most not all cases it just is not worth the hassle , fix the Williams at all cost,.
Go in the back box and press the white button for the sound test (I
believe this to be the upper switch of the 2 on the left side). You
should get 2 tones one tone will test the 1408 DAC sound chip, the
other tone will test the 55536 CVSD speech chip. Knowing which tones
if any you get will help narrow this down before buying any parts. I'll keep an eye on your progress.
Bronk
Parkersburg, WV
