First time poster, so i'm probably doing something wrong - and its likely already been answered before but for the life of me I just dont know the right search terms to hit on my issue as i'm new to this. So here it goes;
Bought a new astro city cab, with nanao ms9 - this is confirmed the main PCB is exactly like the many pictures online. Its set to 15kHz mode.
I have a J-PAC, which is connected to the jamma harness. sync OK and sync IN LEDs stay lit.
The PC I have groovyarcade installed, and I think i've installed to harddrive in standard arcade 15kHz mode, it boots to HDD easily.
Finally the PC has a displayport connector (no VGA), so I bought a displayport -> VGA dongle to connected to the J-PAC.
The nanao ms9 cycles through red, blue, green horizontal lines that shoot up and to the left, all on top of a black screen. I suspect (and hope) this is just a pot tuning issue, but before I go attacking them with screwdrivers I wanted some guidance - am i doing the right thing here?
I should note, that before my attempted MAME install with J-PAC the cabinet had a simple jamma pcb installed and I haven't touched any of the monitor pots.
Thanks donkey.