Initially I posted this in the monitors sub forum, but was recommended I post in this one by buttersoft, so here goes!
I am trying to get the latest collaborative GroovyArcade 2020.06 to work. I have a passively cooled HD 6450 1G DDR3 PCI-E HDMI/DVD-D/VGA card.
I have a Philips CM8833-II 15Khz monitor and a retroelektronics pro-gamer supergun that I use successfully for testing jamma arcade PCBs.
I initially connected the VGA port to an Ultimarc JPAC so that I could use the supergun to test the video output on the Philips monitor. This wasn't working, it was giving me squiggly lines (like bad h-sync) during the groovyarcade monitor tests, and the JPAC's sync-ok LED wasn't lighting. With both jumpers removed the JPAC is supposed to output composite sync I believe. However when I removed the jumpers, the sync-ok LED was lit, but still the monitor was showing squiggly lines like bad h-sync.
I have now hooked up the VGA cable coming from the HD 6450 card to my scope. During the groovyarcade boot up, when it does the monitor tests, I register only 48.1Khz on the h-sync pin, with 2us pulses. Seems to be negative sync too, each pulse down to -5v (shouldn't the pulses be unamplified/sub 1v?).
I guess this would explain why the JPAC wasn't able to find the sync in range?
I also briefly tried to measure the v-sync pin on the vga cable, but I couldn't get anything legible from the short time the test was running. It's hard when I don't have a monitor screen showing the test output. The scope was just showing the frequency massively jumping around, certainly nowhere near 60Hz.
Any ideas what's up? I'm assuming during the monitor tests, the VGA card should be outputting 15Khz, and I thought the 6450 was a supported card.
I have 2 of these cards, both do the same thing.
Thanks for any help.
James