another very good option.. keep the astro for horizontal shmups in jamma 15khz. and if you want a second cab, go for a "naomi universal cab" as a second japanese cab. because..
1. they dont cost much nowadays. about 350€ !! (you just have to "chop"/ cut the legs and it becomes nearly as this picture of "naomi "new" net city")
2. the monitor is 31K. so it's VGA ready. (the xbox360 has a direct Vga output with the good cable)
3. add a hackpad too.
4. ready to enjoy good Tate shmups in hi-resolution.
is a possibility. But:
1. they are cosmetically not the best looking ones, even chopped, IMHO, especially standing next to an Astro City
2. the 31K monitor in the Naomi cabs are not the best ones around, and for some reason have very often (heavy) burn in problems,
3. Hi-resolution means in this case 640x480, which is still awesome.
I know what is causing this, it is because of a bad advise from me. Just put the switch back in the original position, because what you did was switching the monitor to 24K and because the game pcb´s video output is 15K, it isn´t and it will never sync.
My mistake, I told you that this was the flip connector.
On the good side, you now know how to switch to 24K.
But I also have the real solution for flipping the image, you have to flip two connectors on the monitor chassis, just scroll down this page for a clear picture (I saw that you have the connectors on your board also):
http://forum.arcadeotaku.com/viewtopic.php?f=26&t=16156