Software Support > GroovyMAME
Artifacting on Nanao MS8 29FSG w/ CRT Emu Driver (SOLVED!)
Foxhole:
Well, I've seen very weird defects on cards that have been overclocked in the past. It won't come to me as a shock if this turns out to be a defective gpu.
Do you know if your gpu has worked correctly or did you try crtemudriver straight away after getting the card?
BumbleChump:
Actually, I got this card brand new back in 2009 for my gaming computer. It's always worked fine as far as I know. I never overclocked it or did anything weird to it.
BumbleChump:
I tried the other graphics card, no difference at all.
So I measured the voltages across RGB and Sync on my Neo Geo, each color is about 0.49v, and sync is about 3.3v. Lines up with what I've read online.
But the JPAC is outputting the following:
Red= 0.18v
Blue = 2.14v
Green = 1.31v
Sync = 3.08v
This can't be right, can it?? Anyone have some insight?
Zebidee:
Try isolating/bypassing your JAMMA completely and feeding video signals directly into the monitor. Signal should be weak but visible - see if you still get artifacting. If the artifacting disappears, then it looks like your JAMMA or maybe the jpac is the source of your problems.
You shouldn't be getting any sparks when connecting JAMMA, even when power is connected (this is bad form anyway, you might cause some damage). Video signals are very low voltages. There are 12v & 5v available on JAMMA if you have a DC power supply connected inside your cab, but even then sparks would be unusual and alarming. I suspect that you have some problem with the grounds in your JAMMA connector.
BumbleChump:
Thanks for the info. I would bypass the Jamma, but my monitor doesn't have a VGA connector. I could splice it up, but I'm going to try another thing first.
I also realized it's actually ghosting, not artifacting. When I switched the screen to 640 x 480 @ 30hz, I noticed the mouse cursor was clearly ghosting as in, multiple mouse cursors appearing.
More reading has led me to find this:
"A separate video ground connection to the monitor can help to maximize picture quality, so many arcade
cabinets are wired this way. Pin 14 of the JAMMA standard is allocated to 'video ground', which is this
separate ground connection. However, many classic-era arcade games don't have a separate video ground
connection: they assume that the monitor is connected to the same ground as everything else. These games
need a connection from video ground to power ground to work correctly in a JAMMA system. "
https://martinjonestechnology.files.wordpress.com/2014/11/jamma-fingerboard-instructions-v1-1.pdf
I also found someone who had a similar issue. They replaced their entire Jamma harness and got ghosting issues with their Naomi. He ended up cutting a ground from the "video wire" (I'll assume video ground) to solve the problem.
https://www.arcade-projects.com/forums/index.php?thread/5589-strange-ghosting-after-jamma-connector-change/&pageNo=1
On top of all of this, the wiring diagram for a New Astro City shows that the video ground does not connect to the others grounds.
http://1.bp.blogspot.com/-kIQl10gvTe0/UmZud3tXqxI/AAAAAAAACcs/mJXdU4cbKQ4/s1600/Sega+New+Astro+City+Wiring+Schematic.png
If I remember correctly, when I tested continuity on the cabinet's Jamma harness, the video ground and general ground were connected. I'm going to break this connection and see if this helps. If it doesn't, then I'll splice the computer's VGA directly to the monitor.
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