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.

This entry was posted in Arcade, Arduino, audio amp, DIY, Pinball, Star Trek: Mirror Universe Pinball and tagged , , . Bookmark the permalink.

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