I'm sure this topic has been discussed for years, but here is a recent example of fixing the problem. Had a terrible 60hz hum in the speakers of my Batman Forever (Data East, early Sega) that was driving me crazy. When you play the game, you really couldn’t hear the noise, but with the game powered on and sitting idle, the hum was terrible. Figured the noise was coupling into the audio path somewhere from the power supply. As such, I installed an auxiliary power supply to power the sound board and the hum is completely gone! Night and day difference. Here are the parts I used:
Artesyn LPT42 (5V, +/-12V, 40W) power supply – Digikey part number: 454-1075-ND
Molex 3 position .156 Housing (for AC input power to power supply) - Digikey part number: WM2123-ND
Molex 6 position .156 Housing (for DC output and for Data East sound board connection) - Digikey part number: WM2126-ND
Molex 18-20awg crimp pins - Digikey part number: WM2313-ND
The power supply AC input is connected to AC power after the main power switch (spliced into the line/neutral wires going to the transformer). Built a new wire harness that connects from the auxiliary power supply to the sound board. You will need to download the datasheet for the power supply for the 5V, +/-12V pin outs to build your harness. Entire project took about an hour. All stock wiring for sound board is still in the game. Works perfect! Hope this helps someone…
20191225_204505 (resized).jpg20191225_204511 (resized).jpg
