E2099-18 Sound ROM / Schematic / FO manual

[Lan]

I have an E2099-18 with a sound board that does not produce game sounds. At idle it'll produce a soft rhythmic tic, and during reel-spin the ticks seem to increase and go with the speed of the reels, but nothing resembling game sound. Pressing the self-test button on the top does nothing.
Power is good, and board has been recapped. I've tested the CPU, PIA, 6810, and the AY-3-8910 in my Backbit chip tester successfully. The ROM has stuff on it but I have nothing to verify it against. Sound ROM is labeled "561-2"


I have a part layout of the sound board from the generic E-series manuals, but no schematic.
Also, if anyone has a link to the game specific manual, that's be awesome

[Lan]

update:

I was able to find some sound schematics on "Bingo Pinball"'s file archive: https://bingo.cdyn.com/slots/bally_manuals/

After unplugging the noisy cabinet fan I found that pressing the self-test button on the card does produce a faint scale of notes and some game sounds. With the pot at full, the sound is barely audible, but does go lower on changing the pot. Looking at the schematic that leaves me with the LM3900 at U8 and the TDA2002 amp at U9. As the volume pot is having an effect, and I've gotten some loud hums and pops out of the speaker during testing, I'm guessing the TDA2002 is good and will try changing out the LM3900 op-amp to see what happens.

[Lan]

Replacing the LM3900 @ U8 brought back good sound from the test button, solving the sound board issues.

However connecting the data cable back to the 'display & sound driver' board resulted in the ticking and humming returning, no games sounds, and the test button on the sound board no longer doing anything.
 Probing the pins on the cable I found that the pin 1 was not the one with the screen printed arrow pointing at it, and I had the cable in upside down. Flipping that, the humming went away and I had coin-insert sounds!

 Unfortunately I only had coin-insert sounds... Looking at the schematic I suspected the 74LS273 @ U4 on the 'display & sound driver' board was the culprit. Replacing that brought all sounds back