Lines on the screen

[DEL 707]

Not much of a fault, more of a slight annoyance.

I have a MVS MV-FZ1, connected up to my TV via RGB scart. All working fine, but sometimes on the TV I can see what looks like very faint lines moving diagonally across the screen.
It's most noticeable on the white Neo Geo startup screen.

Any idea what could be causing this?

 

[xsq]

sounds like interference... maybe something isn't grounded right or the cables you're using aren't shielded enough? What PSU are you using? Internal or external video converter? LCD or CRT? Any cell phones or audio equipment near by? Is there another monitor next to the one you're using?

 

[ChuChu Flamingo]

sounds like a ground loop

 

[Pasky]

sounds like a ground loop

This. Do you have extremely long cables?

 

[DEL 707]

Here's some pics of my amateur attempt at a CMVS

The board sits about 1/2 an inch above the PSU.
I took the board out of the box and tried a game, but I'm still getting the lines. Again, not a major annoyance, just something I see now and then if I look hard enough.

sounds like a ground loop

What's that? And how do I fix it?

 

[Pasky]

You got your video lines hovering over the PSU unit. Do some wire management and move them off to the side as they're probably picking up interference from it.

What's that? And how do I fix it?

http://en.wikipedia.org/wiki/Ground_loop_(electricity)

Keep wires and cables to the minimum length needed and manage them properly (i.e., not letting them sit on top of a Power Supply).


EDIT: Might be a good idea to put a shielding plate between the PSU and the MVS PCB, just a piece of metal that's grounded in between the two fully covering the MVS PCB, since it appears the PCB sits right above from the PSU. Probably not necessary but it wouldn't hurt. Just make sure the PCB isn't sitting on bare metal.

 

[skate323k137]

Does sound like a ground loop.

On my HAPP PSU's if I use them with a PVM, I have to bridge JAMMA ground with EARTH ground right at the PSU terminals. It eliminates the interference entirely.

 

[Xian Xi]

If it's moving diagonal it means more that it's the sync pulse that your TV is barely holding on to. If it has an auto adjust for sync then use it.

 

[DEL 707]

Does sound like a ground loop.

On my HAPP PSU's if I use them with a PVM, I have to bridge JAMMA ground with EARTH ground right at the PSU terminals. It eliminates the interference entirely.

Your making my stupidity more noticeable, I understood you completely up to "HAPP PSU's"
What's a PVM?
Are you saying I should connect the JAMMA board ground up to the ground connector on the PSU?

 

[skate323k137]

Your making my stupidity more noticeable, I understood you completely up to "HAPP PSU's"
What's a PVM?
Are you saying I should connect the JAMMA board ground up to the ground connector on the PSU?

Yes. Try connecting the earth (AC ground) to the JAMMA common (ground) at the power supply. I had the exact same diagonal lines on my display until I did that. You could even test by just jumpering it with a short wire or paper clip while looking at the screen.

A PVM is the best we get for RGB in the USA, since our TV's didn't have SCART inputs. Basically what I meant was using it on a normal display with a supergun, not in a cabinet. This issue was absolutely horrible with my hyper neo-geo, noticeable on my CPS2 and MVS as well. see http://www.neo-geo.com/forums/showthread.php?246991-Hyper64-Video-interference-quot-fixed-quot

 

[DEL 707]

Yes. Try connecting the earth (AC ground) to the JAMMA common (ground) at the power supply. I had the exact same diagonal lines on my display until I did that. You could even test by just jumpering it with a short wire or paper clip while looking at the screen.

Want to make sure I'm right here, you want me to connect the AC Earth (green wire) up to the Jamma common (black wire)?

 

[DEL 707]

Bit slack on my part, finally connected up the Earth to the common.
Problems been fixed, I am noticing some static on the sound if i crank the volume up, but I take it that's my piss poor wire management.
Thanks everyone.