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SYSTEM-18 video ground issue???

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SMD88

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I have a couple of S18 boards that I paired with an original Shadow Dancer and Alien Storm ROM boards. I also made a Moonwalker board.

The Jp Alien Storm (with unencrypted ROMs) and Shadow Dancer worked in my Blast and NAC, but the picture was completely scrambled. I have read that it can be an issue with video ground, what is the easiest way to fix it? A JAMMA adaptor board on the motherboard with pins 1 and 14 (think that's right) connected by a wire? Or is there a simple fix to the JAMMA harnesses to make them work?

Moonwalker did not have the issue ironically, but had issues due to the ROMs used. Still have not been able to re-burn it with the ROMs Apocalypse made for the 2nd version of the ROM board. The Moonwalker ROM board is the 2nd version (I can use the Bloxeed ROM board, though), the other two are the original ROM boards. It made me wonder if the ground issue only effects the original ROM board? I never tried the Bloxeed ROM board before changing it.

I recently bought a Jp D.D CREW board, but will not be able to test for a while to see if the picture is stable.
 
System 18 has video ground normally connected. I don't see a good reason why it would be cut either.
 
I remember reading it is something to do with the JAMMA harness in the NAC and Blast lacking video ground?

I may need to test the Shadow Dancer and Alien Storm boards on the Clutch Hitter board that Moonwalker occupies.

I did have some bent pins on the ROM board connectors on both the Alien Storm and Shadow Dancer motherboards which I am pretty certain were all fixed and connected. Could one of these pins being not connected cause the ground issues?
 
It's a motherboard issue, not a ROM board one. Try swapping the ROM boards over to the one that's paired to Moonwalker.

Astro and Blast definitely have video ground wired to the monitor.
 
Will do. I have the D.D CREW board I can try now too, as well as a 2nd Bloxeed coming. D.D CREW will stay D.D CREW, though.
 
Where on the motherboard is the synch controlled? Where should I start looking for issues?

I will have to get the Bloxeed ROM board back on its original motherboard to see if it works. The board was shown to be working 100% fine in the auction photos.

The other motherboard was an empty mother I received in a junk lot a few years back with Puyo Puyo 2, 1944 The Loop Master and Kikaioh. There are 3 traces off the 315-5313 custom that were repaired, but I confirmed that the traces are good and have continuity.

It really has me stumped. I seem to remember having a synch issue with my Shinobi S16B board on my Blast, but not my NAC. Synch was screwed on the Blast. That was with the dodgy looking harness it originally came with, though. I have since replaced it with a NOS JVS/JAMMA Blast harness. But never tried Shinobi again on that Blast.

I am thinking of doing full re-caps on both problem boards. I want a fully recapped board to eventually use with the multi when my turn comes anyway. I will keep the Clutch Hitter mother for the Moonwalker conversion. Clutch Hitter actually came on a Moonwalker board, so it's perfect!

EDIT: This is the exact issue I had with my Shinobi, but only on the Blast. Was fine on the NAC. Hmmmm, may have to check that chip. Is the synch chip on the S18 similar?

https://www.arcade-projects.com/threads/help-with-shinobi-system16b-issue.25208/
 
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I may be missing something, but I cannot see anything attached to pin 14 of the JAMMA edge connector. I see a trace, but it goes nowhere, on both sides.

I looked at the Shadow Dancer board, and could see nothing broken or scratched on the board. It really is near immaculate for a "junk" board!! Apart from the aforementioned traces off the custom that are repaired.

I pressed down on the SD ROM board, and it seemed to go into the socket more. So I dismounted and re-connected the AS ROM board from the Bloxeed. Two of those previously bent pins had no issue becoming bent, again!! Fixed them up and re-seated the AS ROM board. Problem is, one cannot know if the pins are re-bent without taking the ROM board off, potentially killing the pins on the board.
 
system18_moonwalker.jpg


Shows continuity to GND.
 
a long time ago with romset from apocalypse I had this issue:
image111-jpg.jpg


So one guy from this give me the solution for my rom board model:

20210626.jpg


20210624.jpg
 
nonosto said:
a long time ago with romset from apocalypse I had this issue:
image111-jpg.jpg


So one guy from this give me the solution for my rom board model:

20210626.jpg


20210624.jpg
Click to expand...
Ahhh, that is what my Moonwalker board looks like. I am thinking that I will just move the MW ROMs back to the Bloxeed ROM board and use the Clutch Hitter for Desert Breaker. No need to fiddle with re-burning that way.

No idea why I did not try that in the first place! My MW did not work at first because I had the wrong decrypted ROMs with the Jp set. Probably would have worked perfectly on the Bloxeed ROM board. Likewise, if I had realised 3 years ago when I got the Shadow Dancer ROM board that the ROMs were not protected, I could have been using the "junk" S18 motherboard since then.
 
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nem said:
https://www.arcade-projects.com/thr...nt-purchases-thread.1970/page-692#post-380941

Apparently, it has weird sync. I had no idea.

Have you tried adjusting horizontal hold?
Click to expand...
Ahaaa! So it can have weird sync. I think I tried adjusting it on the NAC, but my OSD menu on my Blast I tested it on does not work. Have to get it sorted. Unless it is the setting on the actual chassis you are referring to? I had never seen an issue like it before, other than the aforementioned Shinobi on this same Blast. All boards I have ever bought just work!

So perhaps the Moonwalker PCB that Clutch Hitter came on is a later revision, I am hoping the D.D CREW ones are the same if that is the case. I will have found my future multi donar if it is.
 
On the NAC, if the monitor is a MS9, try adjusting H.H. 15 on the chassis.
 
@SMD88 it's a known issue with first revision motherboards. Those have 2 oscillators. There's a second revision with 3 oscillators that fixes the issue.

@nonosto the set you used isn't from Apocalypse. I used the same link as you (I guess) and ran into the same issues. Then someone over here (can't remember who) sent me the properly patched set and it worked beautifully (no messy wires).
 
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