Hi all! First time posting. I am rather new to pins, I've been working on them on weekends since mid last year, so I've become a bit familiar with them but am still learning. I am much more familiar with arcade games, but I still enjoy pinball. I actually was finally able to pick up a machine of my own, a Gottlieb Street Fighter 2.

To cut to the chase, this thing isn't booting and has me a bit stumped. I get some text on the screen (as shown in the picture) such as "Free Play" and a bunch of numbers. The same thing flashes on the screen several times as if it is resetting.
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Here's what I've done on the CPU board: verified the voltages, verified the ROMs against what was floating around in the pinMAME set, replaced the 74HC123 as I've read that this can be a problem child, replaced 1uF ceramic capacitors C20 and C21 as they had drifted out of spec (also read that they are problem children), verified resistors R5 and R6 to be 680k, Verified the jumpers to be correct for the ROM and the RAM, verified the 6264 RAM out of circuit, and finally changed the battery with a fresh one. I also started poking around on the CPU to see what those signals were doing, reset is not toggling after boot, interrupts are not happening (not sure if that is correct, none are pegged low so I don't think it's stuck)

I haven't begun too look much into the display driver board, I have two of them and both do the same exact thing, so I figure it to be a CPU problem, but I've also read that these can be a bit troublesome. I see that the LED is blinking, but that's not a very good indicator that it's running correctly...

What I am looking for here is some advice as to where I should troubleshoot next. I am currently at a loss as to what I can do here. Any tips? Sorry for the lengthy first post!

So I've tried swapping around the ribbon cables with no luck, so I do not believe it to be a connection issue. Weirdly enough, I got it to boot by messing around with the voltage adjustments (Turning it up then back down), but I only heard one tone, so I'm wondering if I have sound issues. I threw it into test, it passed the memory check, all the lights worked, but sound just produced some buzzing. No LED action at all signaling that it is alive. Whats even weirder, is that sometimes it would boot with no display at all, so I have to wonder if it is a CPU board issue or not...

As far as I can tell, the only previous work has been done by me. These two boards were not original to this machine however, they came out of a box of boards I was borrowing. I ordered some new repro boards to help me diagnose these issues. Best case I have an extra set to sell, worst case I throw them back in the box until later.

I have tried that, the minimum required here is the A1 cpu board and the A8 DMD controller. One can't boot without some kind of communication from what I've read.

It would be much appreciated if you could share the test roms with me, I would have just sent you a PM but unfortunately my account is too new (haven't hit that 48 hour min).