Neo-Geo monitor issue

[Chrisdice]

Can anyone here help me solve this problem with my Neo-Geo. I am having the same exact issue as described here in Neo-Geo forums. I bumped the thread but no one there responded.


I just bought a brand new monitor, and I have the same problem still. These are faint horizontal lines that scroll upwards, then slow down and disappear, the reverse directions. It's really only evident on lighter colors such as white or sky blue. Sometimes the lines aren't there at all, so there must be a way to correct this problem. I've tried unplugging the lumi-panels, trying different outlets in my house and I even tried an AC line interference filter. THey are still there and it's driving me mad. Could it be my power supply needs replacing??
scrolling horizontal lines on my monitor. AAARRRGGH!! - Neo-Geo Forums

Do you guys think it could be the power supply? I tried everything else.
the power supply I have is a A-Matic UE150-HB

[musky]

Without seeing the lines it is hard to tell exactly what is going on but I would guess that there is a capacitor in the video circuit that is breaking down or leaking some what that is causing the problem. It sounds like some of the vertical sync problems I've seen in other equipment

[Chrisdice]

Without seeing the lines it is hard to tell exactly what is going on but I would guess that there is a capacitor in the video circuit that is breaking down or leaking some what that is causing the problem. It sounds like some of the vertical sync problems I've seen in other equipment

The lines scroll horizontal and are real faint. It wouldn't show up in a picture. It starts out worse when the game is first powered on, then seems to almost disappear after 5-10 minutes. Then comes and goes. Sometimes going up and sometimes going down. My first guess would be the monitor but this guy replaced his and still has the same problem. It seems all thats left to try is the jamma harness and the power supply. Am I missing anything?

[musky]

are you working on a console or arcade Neo-Geo. Does it look like retrace but only in a band about an inch high that scroll up or down

[Chrisdice]

Its an arcade mvs 2 slot unit. I'd say about 1/2 inch or less lines. Almost like noise interference. click on the thread link in my first post for more technical info.

[musky]

Like I said, it' just a guess on my part, could it be a hum bar? Which whould lead me to look a leaking cap somewhere. It comes and goes which makes it so much easier to find...yeah right, and it scrolls just like a 60 cycle hum bar would do on a 70 htz vertical sync monitor would. I don't think it's power supply although it could be. I would have to see how things are set up

[Lddrizzt]

I've seen something similar on computers. Once the refresh rate was changed it went away. Don't know if that is helpful...

[daverob]

My first guess would be a leaky B+ capacitor. This would be an electrolytic capacitor mounted on the neck board on the back of the tube. Probably rated somewhere around 22-100uF at 160v. I've seen these symptoms on several makes of monitor with the same cause, most of them have been WG models, but a few Nanaos and Hantarex thrown in for good measure!

Alternatively similar symptoms can be caused by poor grounding. Check the grounding on the Jamma Harness, monitor chassis and power supply all get good continuity to the earth pin of the plug (you are using a three prong plug?).

It could also be picking up ground noise from another appliance via the mains lead. Try plugging it into a different outlet, or switching off any potentially noisy appliances in the house (fridge, microwave, Aircon etc). You could try a surge protector, but most of them are useless for this type of noise/interference.

It could be the power supply. The big capacitor on the mains side might have dried up. But if it's not regulating correctly, then you should be able to measure some AC noise on the DC outputs with a multimeter. It might be worth swapping it out if you've got a replacement handy, but my money's on the monitor or a grounding problem.

[Chrisdice]

well I hope its not the neck board. The issue started (I first noticed) when I turned up the flyback on the back of the monitor to brighten up the screen. Of course the first thing I tried was to turn it back down but the lines didn't go away. Yes its a 3 prong plug and I did try different outlits. I'm not sure about the grounds. There are ground wires in a few places conected to different screws. They all seem tight and secure.

[musky]

My money would be on Daverob for this one, seeing how you did kick it up a notch, probably was enough to start a weak cap to start leaking by.

[Chrisdice]

I don't have anyway of testing the leaky cap right now, I need to get a hold of another wg 25" chassis. The monitor does have an isolation transformer so does that rule out the ground loop? I'm trying to learn as I go by googling all these terms you and Daverob are using. I never even heard of a ground loop until now.

[Chrisdice]

Update..Looks like its the neo mother board. I connected another jamma board to the harness and no lines.

[musky]

Cool, I like playing MetalSlug on my Mame NeoGeo

[Chrisdice]

I just got metal slug x. what a great game. I didn't think it would be so much better then the first one but it is.

[JohnD0406]

Wow.. Didn't expect to see technical arcade info here, but I guess it makes sense that if you collect one type of machine, you're likely to have others! I had several arcade machines, but am down to a Star Castle and a Tempest (both vector monitors, which are not the same to play in emulation). Fired up the Tempest today to find the blue gun off... probably just connectors need cleaning again, but that's another day.

[Chrisdice]

Its something when I can get better help here at pachitalk with my Neo-geo, then I can on Neo-Geo forums. Still no response over there.