Bally (AS-2518) Audio Card tester

For the past week or so; I’ve been working on the Audio solution for the Star Trek: Mirror Universe project. I’ve decided I want to combine a Raspberry Pi with the guts of a Bally AS-2518-32 soundcard. These cards are not yet rare; but the PROMs and the 4bit counter on them are rare. As a result; I’m going to be trying my luck with the first Complex Programmable Logic Device (CPLD) project I’ve ever embarked on. More on that later tho.

Given I’ve designed a replacement sound card out of new components; I wanted the ability to test the card outside of the machine… because I don’t want to risk burning up a perfectly good Bally CPU board with a risky design.

I spent quiet a bit of time looking at the schematics of the AS-2518 Bally sound cards to understand it’s functionality so it can be duplicated. The result is that I decided to design simple micro-controller-based tester which would sequence my new design thru all 32 tones generated by the on-board logic.  Since I already had a Arduino Nano (purchased from FRYs) for the Pinball Nixie Display project – I re-purposed it for the Pinball Audio Tester.

I began by rewiring the cables for the Audio board as follows:

J1 (Audio)	Arduino Nano (PAD)	Color	Cable	NAME (AUDIO)
12	D2	Orange	1	SOL_E
11				<KEY>
10
9
8	D8	Yellow	2	sol_bus_sel
7				NC
6	GND	Bare	2	BARE(GND)
5	+5V	Red	2	+5v
4	D11	purple	2	SOL_D
3	D12	brown	2	SOL_C
2	D13	grey	2	SOL_B
1	D7	blk	2	SOL_A

I’ve decided to share the Source code so that other Pinball hackers can take advantage of my work. You can download the source code from here:

PinAudioTester.ino Rev 0.1

The source is simple and should be easy to understand – please consider sharing any improvements you decide to make.

To power the Arduino and the soundcard; I created a 4pin Power cable which plugs into my debug ATX powersupply with color-coded aligator clips. I attach the Red (+5V) to the TP1 test point, Yellow (+12V) to the ?TP3? testpoint, and Ground (Black) to the TP2 testpoint. The design does not currently test the 43V to 12V linear supply as ATX doesn’t output that high of a voltage.

I’ve tested the source on my original AS-2518-32 sound card and it outputs 30 tones and two silences as implemented in the pROM. I now await the new soundcard PCBs from OSHPark to do some final testing.