Hey guys, I found this sound board in an unknown state and wanted to test it. It's labeled as-2888-4 and has the prom for paragon/harlem.

I don't own any of these pins, just a grand slam which uses a -51 board. I wondered if it can be tested on a workbench.

I've hooked a louspeaker and a power supply at tp4 (43VDC) and tp1 (5VDC). But I can't figure out what combination of low/high signals I have to send to sol_adress A to E to produce some sounds.

Pin8 of connector J1 triggers a sound when forced to high as it seems but I'm sure I'm missing something.

Any idea? Thanks!

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Thank you Quench and ForceFlow for making Pinside such a great technical resource

I finally managed to test my -50 sound board in my grand slam which normally uses a -51 board.

I noticed while reading the schematics that -50 and -51 boards share the same connector J1 pinout except that:
- J1-1 is fed with +12V unreg in -51 games but this pin is unused on -50 boards, so it's OK
- J1-9 is fed with +43V in -50 games so it's missing on my -50 board.

The +43V is used for the amplifier section. It can be found on the driver board (banded side of the diode located near the relay).
So it's just a matter of connecting J1 and hooking a wire with alligator clips between the banded side of the relay diode and TP4 on the -50 board.
Then I put Harlem Globe Trotters ROMs on the CPU board to properly test the sounds.

OK, it plays sounds, the concept is validated but as the interruption timer is not equivalent between a -133 CPU board (Grand Slam) and a -35 CPU board, the melodies are played very slow.

I just had to make the same test on a friend's pinball with a -35 CPU (mystic): it worked like a charm!

Here is where to attach the alligator clip on the bally driver board:

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