[help] DIY Supergun (JAMMA)

[nasune]

(To preface this, I'm sick while typing this, so I might not be as coherent as I'd like to be. If that's the case I apologize.)
So as I stated in a post a while back I'm trying to consolize a couple of old JAMMA boards by making some Superguns which I can then install in a custom case (to make a proper console). For the most part everything works well (switches work just fine, the extra power LED works as it should, everything is powered on and functional) except for one thing, the video keeps 'rolling' so to speak. I'm fairly certain everything is wired up correctly (I've triple checked every connection/wire), but the problem persists.
The board itself works properly when checked against a store bought supergun so that can't be the issue. One thing that I did notice though is that the resistance (for the sync pin) on the home made one (150 ohm) is far less than on the store bought one (either 290 ohm or 390 ohm, not sure if the first color is red or orange) although I did keep to the schematics (see picture below). Could that be the issue, or is there something else I'm missing? I'd be very grateful to anyone who can help.

Spoiler

(the used schematics)

 

[fixingmytoys]

rolling might be that your TV is not 60hz, that can happens when a 60hz picture is played on a 50hz only screen

 

[nasune]

rolling might be that your TV is not 60hz, that can happens when a 60hz picture is played on a 50hz only screen

Unfortunately that's not the issue here, two of my TVs can display 60hz (they're modern(ish) LED tvs which can play NTSC and PAL60 games without issue).

 

[fixingmytoys]

check all your GNDS you should have a VIDEO GND as well as just GND

 

[nasune]

Seeing as I have my new multimeter I'll try it as soon as I can (annoyingly the next couple of days are likely to be quite hectic, but worst come to worst I'll just have to do it next weekend). Thanks for all the help.

 

[nasune]

Quick update: I'm at least missing sync ground (not sure how that happened), and one of the wires is broken. As soon as my new solder is here (unfortunately that can be anytime from a couple of days from now to a week or two) I can try to repair it and see if that works. Thanks so much for all the help so far.

 

[nasune]

Another quick update. As it turns out, the schematics I've been using are incorrect. Both sync and sync ground (as well as sound actually) point towards scart input rather than output. Simply repairing the wire and connecting to the proper pins gave me crystal clear video (the audio on the other hand is still not working, but I'll take what I can get ).