Galaxian cocktail cab is giving me a buzz...

[EVEGames]

Literally.

Long story short, I picked up this 1980 Galaxian cocktail cab for $35 (pics below), supposedly in working order, but for $35 I was willing to chance it.  It has these funky levers that function as 2-way joysticks.  Anyway, I got it home, plugged it in, it had lights, fan, sound (you could hear the game start up, play, shooting, Galaxians/me dying), but only garbage on the screen.  I tweaked the pots on the monitor, and got it to the point where I could see some falling, blinking stars in the background, but it seemed the other sprites were all messed up pretty bad.

Right off the bat, it was very flaky, half the time when I turned on the power, the monitor would come on, and the other half it would not.  I opened it up, tightened all the connections, and now it fires up reliably each time, BUT now all I get is garbage on the screen, and a constant tone buzzing out of the speaker.  It is not like a 60Hz hum or anything like that, it's like the beep you get during a POST-test on a PC, but it's constant.  I'm wondering if that is possibly something the PCB is doing on purpose?  Where would I start to troubleshoot this?  Any help would be GREATLY appreciated.  Pics below.

On this one, the machine is off... that's just phosphor burn 


Top-down view.


Monitor.


PCB, with what I was HOPING would be a Jamma harness... it's not.


Now this is all I see when I fire it up...


By the way, is there any JPAC-like solution which would work with that JAMMA-like wire harness in the 4th picture?

[EVEGames]

In case this helps, I also made a (very) short video with sound so you can hear the beep.  It would have been longer, but I ran out of space on my CF card almost right away.