Video noise in picture

demogo

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Hi,

I've been wrestling with a problem for 3-4 weeks now and I'm hoping someone here can shed some light on it.

Basically, I'm getting some interference patterns on my monitor with my NBA Jam boards.

They kind of roll through the picture. At times they slow down, stop briefly, and then roll through the picture the other way.

I'd take pictures and post them but it's hard to get a picture where they really stand out.

I've tried tying cabinet ground to logic ground and that didn't seem to help. I've moved the AC plugs for both the monitor and cabinet onto different electrical outlets. That didn't help.

I've taken the boards and plugged them into someone else's Jamma cabinet and didn't see any issues. The KLOVer who sold them to me didn't see the issue either.

If I move the Jamma plug in this same cabinet back to my Gauntlet Legends boardset then I don't see any issues.

I've tried moving the jamma wires into a different area of the cabinet farther away from the power supply and that didn't help.

A somewhat flaky jamma extension harness seemed to make the problem worse. (extension harness is being returned).

The only things I can think of at this point is to buy a cheap jamma game and see if it shows the same problems and to wrestle my spare Visionpro monitor out of the closet and try to wire it up temporarily to see if I have the same issues with that. (I don't have any of the material to make cables long enough to sit it outside the cab so this will be a major PITA but it can be done).

So what have I missed??? Any ideas? Anything at all to try to shed light on what might be causing the problem?

At this point even if it doesn't solve the problem but might shine a light on what the problem is, I'd definitely do it.
 
NBA jam does have a really funky sync.

NOt sure if that is the source of your problem.
 
Didn't the this also have a mini sub board with ferrite core connections?

I know that Primal Rage had that stuff... For some reason, I thought that NBA Jamm did too.
 
NBA jam does have a really funky sync.

NOt sure if that is the source of your problem.

Interesting.

The monitor manufacturer told me to add a 22uf cap to the sync line because GL was sending some voltage on the sync line and the cap would take care of it. (It was causing the multisync monitor to lose sync).

He was right; the cap fixed the issue and GL works great.

But I was wondering if it was causing this issue so I put a jumper on each end of the sync wires (with the cap still in place) and that didn't seem to make any difference. I'm half-tempted to unsolder the cap completely but I'd think the jumper would work around the issue if there was one.

The ferrite choke is an interesting idea; can't hurt I guess.

> and also twist the video wires while your at it... That will put the curb on any outside interference.

Will give this a shot. Right now the wires are bare whey they are soldered to the wires for the monitor; I really need to put a proper video connector there again.

And GL has no video issues at all; picture looks great.
 
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Didn't the this also have a mini sub board with ferrite core connections?

I know that Primal Rage had that stuff... For some reason, I thought that NBA Jamm did too.

I'm not sure I understand your question. It has a sound board.
 
noise

Maybe a quick fix is to take off your ground wire going to your monitor at the monitor ac plug or if a seperate ground is attached to the monitor frame somehow. I have seen that hundreds of time and not all are from boards. Some are from lights,isolation transformers,bad outlets,etc....
 
That's an interesting thought.

Right now I don't have the monitor wired into the power plug coming from the power supply; I just have it wired into a separate AC outlet (while I screw around with other stuff).

I guess that would give the monitor a different ground than the one from the power supply???

Could that be it?
 
Heh -- nope, wasn't that. Just checked it real quickly before I turned in and not having a ground plug for the monitor made no difference. (Plugged it into a 3 prong -> 2 prong adapter).
 
try adding a wire jumper from the frame of the power supply to the frame of the monitor.

And I still think you're picking up electrical interference through the air.,,,
 
Do those ferrite chokes really work?

I have an Xbox project that is picking up some feedback... Maybe I should put one on my video wires.

I'm not sure I understand your question. It has a sound board.

On second thought, I don't think that NBA Jamm had a filter board.

MOre on the sync issues:
These games use a vertical sync. frequency of around 56Hz ( the majority of games having a vertical sync of around 60Hz )
 
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I just tried a jumper from the power supply frame to the monitor frame and that didn't change anything.

I also just unplugged/turned off virtually everything in the house that uses AC except for some digital clocks and my DVR and retested and that didn't make any difference either. Nothing with motors was on, fridge off, air conditioning off, all lights off.
 
Try another boardset - does it still have the interference?
Check your B+ - ensure that isn't out of control.
Really suprised that Mods idea (running seperate ground to frane) didn't fix it.
 
Hard to be certain without the pics, but I agree with Mod. Sounds like RF interference. Is there a transmitter near you? (radio, cell, etc...)
 
I just tried a jumper from the power supply frame to the monitor frame and that didn't change anything.

I also just unplugged/turned off virtually everything in the house that uses AC except for some digital clocks and my DVR and retested and that didn't make any difference either. Nothing with motors was on, fridge off, air conditioning off, all lights off.

Try grounding your CP straight up... Sometimes, the metal CP can act as an antenna. Also, disconect your audio amp.... That can give you some feedback also.
 
Try another boardset - does it still have the interference?
Check your B+ - ensure that isn't out of control.
Really suprised that Mods idea (running seperate ground to frane) didn't fix it.

Another boardset is next on my list I guess. I don't have another boardset so I guess I'll have to buy a cheap jamma board to test with.

My monitor is new; I'll have to email the company I guess and find out where I can test the B+ at.

Regarding the game itself, the #%&!tard that sold me the game threw a power supply in the cab at the last moment that was set WAY too high and I was getting 6 volts on the 5v lines. I dialed the voltage back but it didn't seem to make any difference. Gauntlet Legends had been taking the overvoltage w/o any issues but this board never has had a good video signal.

I'll try running the jumper from a cabinet ground to the monitor frame but I think running a jumper from the power supply frame is the same thing.
 
Hard to be certain without the pics, but I agree with Mod. Sounds like RF interference. Is there a transmitter near you? (radio, cell, etc...)

Not that I'm aware of.

My wireless router. :)

(Oh, I guess it was powered off as part of my test)
 
Try grounding your CP straight up... Sometimes, the metal CP can act as an antenna. Also, disconect your audio amp.... That can give you some feedback also.

Definitely have a good ground on the CP -- I've checked it.

Not sure where my audio amp would be?

I did unplug the marquee light from the power supply to see if that helped and it didn't. Same interference.
 
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Try another boardset - does it still have the interference?
Check your B+ - ensure that isn't out of control.
Really suprised that Mods idea (running seperate ground to frane) didn't fix it.

I ran a jumper from ground to the monitor frame; no effect.

Disconnected the 12v fans used for cooling GL; no effect.
 
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