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Nintendo Vs. PCB, bad image (solved), audio affecting image (solved)

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Hi there!
Have recently purchased a Vs SMB pcb, which works fine, but has terrible image. Lots of ghosting and jailbars like artifacts.
It came with a hand made inverter and amp board. I have tried to solder 5v, gnd, r, g, b, video gnd, and sync directly to the Jamma connector, to see if the inverter board could be the issue, but all I get is a black screen, or lighter if I dial up the brightness, but no visible image.
On the main pcb, C8 seems missing, although I don't know what it's for, and not all board revisions seem to have it at all, if I google some photos.

Some photos of the pcb, inverter board and image on the monitor can be found here:
https://photos.app.goo.gl/GEDKJFm2jpf9ns6a8

In real somehow ghosting and jailbars look much worse than on photo by the way.
I could try and order a new inverter/amp board, but it's kind of pricy just as a test so would be great if I could localize the problem somehow. Anyone who's seen this before, and might have any directions on what to check or which route to go?
Many thanks, Bart.
 
One more thing to add -
I'm noticing the image reacts to the sound quite a bit, brightness going up and down along with the game music and sounds. Altogether looks like a weak video signal somehow.
 
What monitor are you using to test the board? As you likely know, Nintendo VS system boards output inverted video and non-amplified sound. They are not Jamma and a simple harness wont make them compliant with a Jamma set-up. That being said, if you hooked up this board to a standard monitor, the colors should be all wrong but they shouldn't be doing what you are describing.

(1) Although its possible to make a homemake a board to invert video and amplify sound, but that's a tall ask (i.e., that breadboard). No clue if the adapter you have correctly attenuates the signal and I don't think you can troubleshoot that board without a lot of work, equipment and research. I'd just get the adapter from PCB Junkie or from mike's arcade. Those are both pretty good IMO.

(2) IMO, your flyback is too high for this board (i.e., screen pot). Turn that down until the black on screen around the bezel is truly black not grey. If you have a remote board to your monitor with contrast, try dialing that back first. Maybe this will solve what you are talking about?

(3) The VS system pcbs have onboard color controls. The red, blue, green pots near the edge connector. Set those to the lowest setting and turn up each in small doses and see if that helps.

(4) Some VS system games (i.e., gun games like duck hunt) required caps to be removed in order for the light gun functionality to work. There was a service memo that described the process and which ones to remove/populate for gun or non-gun games. Pretty sure that can be found here.

(5) If all else fails, the schematic for the VS system pcb is listed in the manuals I linked, find the video amplifier IC and perhaps look at replacing it or the other logic components in that circuit. That maybe beyond what you want to do, but that is where I would start.

Hope you get this fixed.
 
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Am away for a few days, will thoroughly reply and check some things when I'm back. Thanks for the reply!
 
Plymelk said:
What monitor are you using to test the board? As you likely know, Nintendo VS system boards output inverted video and non-amplified sound. They are not Jamma and a simple harness wont make them compliant with a Jamma set-up. That being said, if you hooked up this board to a standard monitor, the colors should be all wrong but they shouldn't be doing what you are describing.

(1) Although its possible to make a homemake a board to invert video and amplify sound, but that's a tall ask (i.e., that breadboard). No clue if the adapter you have correctly attenuates the signal and I don't think you can troubleshoot that board without a lot of work, equipment and research. I'd just get the adapter from PCB Junkie or from mike's arcade. Those are both pretty good IMO.

(2) IMO, your flyback is too high for this board (i.e., screen pot). Turn that down until the black on screen around the bezel is truly black not grey. If you have a remote board to your monitor with contrast, try dialing that back first. Maybe this will solve what you are talking about?

(3) The VS system pcbs have onboard color controls. The red, blue, green pots near the edge connector. Set those to the lowest setting and turn up each in small doses and see if that helps.

(4) Some VS system games (i.e., gun games like duck hunt) required caps to be removed in order for the light gun functionality to work. There was a service memo that described the process and which ones to remove/populate for gun or non-gun games. Pretty sure that can be found here.

(5) If all else fails, the schematic for the VS system pcb is listed in the manuals I linked, find the video amplifier IC and perhaps look at replacing it or the other logic components in that circuit. That maybe beyond what you want to do, but that is where I would start.

Hope you get this fixed.
Click to expand...

First, thanks for the extensive reply! Appreciated. And nice avatar, really appreciate the abt 12 :)
To answer your questions:

I'm testing the pcb in my MVS U4 cab. I use it for many different boards, and haven't had any issues like these yet.
Have tried dialing back contrast/brightness, but it only hides the ghosting in the black areas, doesn't solve the problem in the (brighter) playing field.
Have also tried setting rgb pots to lowest setting, but even at that setting the artifacts are obvious.

Have checked the caps you mention, but those are all there. The one missing seems to be in the +24V area, which is for the coin counters I believe, so I think that one shouldn't be the issue.

Before getting into swapping the video amp, trying the pcbjunkie or mikesarcade adapter would be an easier first step (especially since the home made looking attached adapter pcb isn't the greatest one to use). However before spending the money on that, it would be great if I can get around the adapter board, straight to the Jamma connector, to check if the image without the board still gives me the artifacts, or not. However, this does not give me wrong colors, but just only a black screen.
Any idea what's up there?
Have soldered P1 connector pins GND (1,2,A,B,21,22,Y,Z), +5 (3,4,C,D), R (9), G (10), B (12), Video GND (11), Sync (13) directly to Jamma (1,2,A,B,27,28,e,f), (3,4,C,D), 12, N, 13, 14, P.
Not sure how this should behave, but wouldn't expect a black screen. Am I missing something here? [01/06/2023 EDIT - In hindsight must have been a stupid mistake, assume I've mixed up Master and Slave side, which I couldn't find clear info about which is which]
 
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Update - Not sure what I missed when soldering rgb directly to Jamma, but when using the adapter board for everything but rgb, which I've soldered directly to Jamma, I don't get the black screen, but inverted colors without the ghosting instead.
So it's the adapter board after all. Will order new one and post when it's tested and expectedly fixed.
 
Update - Pcbjunkie adapter board received, and after some initial issues (board apparently needs -5V, and fits as tight as a board can possibly fit, had to bend pins to connect it at full force with both hands), things are much better now. Ghosting issues are gone. Jailbars still there but a little less annoying, and as I understand are a typical Nintendo VS thing, so I consider that partly fixed.
Interested though if a board recap is likely to improve here?

Problem left is the before mentioned audio affecting the image problem. Volume at zero or just over zero, no problem. Volume a little higher, and the image starts "dancing" along with the sound, as can be seen in the video here:
https://photos.app.goo.gl/fCfDKqX1o28aW7VB8

According to the adapter board seller, audio and video are totally separate, so this could only be caused by an unstable -5V/12V power source. Although I haven't ever seen this with any of my other boards (anyone any idea why?), I do notice that at higher volume, 12V drops and starts going up and down between 11.6-11.8V, so that might indeed be it.
Having said that, not sure which brand of PSU I have (please see images through same URL above), but which is a good PSU I should buy to tackle this problem?

Thanks.
 
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I have zero experience with pcb design but I wonder if the routing of the signals on the adapter would allow the audio to affect the video?
Maybe they’re too close to each other or sharing a ground that should be dedicated to video or audio?
Unfortunately all my VS stuff is packed away at the moment, I do have one of PCB Junkies adapters and don’t recall any weirdness with audio/video but it’s been awhile since I’ve tested it. He makes some great adapters though and I’ve never had any issues with them.
 
Plymelk said:
Try upping the voltage on your power supply to where it reads 12V on the board itself. What else you could do is replace the OP amps that are on the Vs. System boards, LM3900, there are two of them. https://www.arcadepartsandrepair.com/store/integrated-circuits/ttl-chips/lm3900/
Click to expand...
I have measured 12 on the board, that should be fine. It only starts dropping when I raise the volume.
The adapter board seller says he's sure it's the power supply, so I'll try getting 12V from a separate supply first, or using another amp. If that doesn't work, I'll be sure to replace those op amps, thanks for the link!
 
jamesv833 said:
I have zero experience with pcb design but I wonder if the routing of the signals on the adapter would allow the audio to affect the video?
Maybe they’re too close to each other or sharing a ground that should be dedicated to video or audio?
Unfortunately all my VS stuff is packed away at the moment, I do have one of PCB Junkies adapters and don’t recall any weirdness with audio/video but it’s been awhile since I’ve tested it. He makes some great adapters though and I’ve never had any issues with them.
Click to expand...
I have thought of that too. Don't think anything was shared, but thought of small magnetic fields or anything.
For now I don't have a big issue with it since it's at lower volume anyway, but will be working on CPS2 soon, where I'll need a separate amp anyway, will try using that amp then, along with separate power supply, and see what that does. Will be sure to report back (although it could take a while)
 
i have the same problem with the same adapter and my two nintendo vs. boards. on my royal video, blast city, astro city, etc.
you can see the effect of the sound on the image on the 2nd stage of Mario where you are in the underground. The the melody triggers the image interference.
 
VJP said:
i have the same problem with the same adapter and my two nintendo vs. boards. on my royal video, blast city, astro city, etc.
you can see the effect of the sound on the image on the 2nd stage of Mario where you are in the underground. The the melody triggers the image interference.
Click to expand...
Will report back if I have tested some possible solutions as said. In the mean time, if you find the holy grail to fix this, be sure to let me know :)
Btw, if you're experiencing this on different cabs, I assume the chance of all three having a bad PSU will be quite small, and the PSU shouldn't be the issue.
 
Can you adjust the colors with the potientiometers on the adapter from pcbjunkie? Mine are not working, just wondering if this is normal.

I have already considered buying another adapter to test whether it is due to the adapter.

https://www.mikesarcade.com/cgi-bin/store.pl?sku=VS2JAMMA
I think my next step will be a recap for the Vs. board.
 
Yes can adjust colors. Think it's weird though if all three aren't working. Maybe try dialing down or up potmeters on the VS board first, then on the adapter board?

For me personally I think those adapter boards are too expensive to just buy another one to test. I'd rather first try with another amp, as I will need to get one anyway.
 
An update. Have done some testing recently, the problem, at least in my case, appears to be the 12V line indeed.
No clue why this pcb is so sensitive to that, as none of my other pcb's show any related issues, but somehow it is.

First have disabled -5V. Image is white but still bumps with audio, so I can rule that out.
Then have tested with external amp, still the same issues.
External amp powered by external 12V power supply solves the issue.

It's an ugly solution, so I might purchase a new PSU at some point. Will first test with two other cabs I have stocked in my garage, when the temperature gets a bit better, just to test if I can swap out the PSU with one of those.
Think I can mark this one as solved.
 
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