Quoted from DeeGor:Thanks. These were some of favorites when I was younger. Spy Hunter is great, but it currently has an issue with hum coming from the speakers that I'm troubleshooting through. Apparently that's a common issue with Midway games of this Era when using a switching power supply.
Using a large capacitor across the 12v and ground lugs on switcher has been known to fix the hum depending on the setup. If youre using a switcher kit from arcade shop they include one. Also, could be a grounding issue.
Google, mcr switcher capacitor to get some previous solutions.
Here is a pic of my messy game room a few months ago. This is about half of my games. Pile Position Cockpit is now gone and Major Havoc is currently for sale.
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