Neo Geo Cab converted to Jamma, UMK3 and NBA Hangtime boards have issues

Hi everyone,
Been "trolling" these boards for a while, seems like a really good community. This is my first post.

Anyway, I have a question. I recently purchased a cabinet that was supposedly a NeoGeo Single slot cab. There was no MVS motherboard, just a jamma connector. The CP is neo geo though, and the insides kinda verify that it was (there's monitor controls in the front if you open the CP). Now, I've used a few Jamma games in it with no issues whatsoever. The problem comes in when I use my two Midway Wolf Unit boards (I think that's the name of the hardware).

Whenever I boot up Ultimate Mortal Kombat 3 or Nba Hangtime on this machine, there is a soft (but audible) buzz in the speakers. Also, the video looks like its too big for the monitor. The bottom inch of the monitor looks like its squished. This cab doesn't have problems with any other boards, just these two (I'm guessing cause they're the same board).

Now, I've had issues with these boards before. Namely, there used to be this horrible loud buzzing noise when these games were on if there was no +5V on the harness. I've fixed that problem, but there's still (as stated) a small audio problem. I guess it could be a ground issue, but I wouldn't think so since the other boards are okay on it. The video issue is puzzling, although it might be worth it to mention that I have to adjust the monitor when playing these games on my other cabinet (I have to adjust the horizontal position, but that's it). I'm confident I don't need a cap kit for the monitor.

Being a neo geo community, I was hoping someone might have experience with these (or similar) problems. Thanks for reading!

Was the one-slot that was supposedly in it a JAMMA one-slot? Make sure it's not still wired for MVS pinout (which would cause sound probs). And you meant weird sound without -5v, right?

No, it was +5V. I had a Konami X men cab that I was using, and it would produce a very large buzz on NBA Hangtime if I didn't connect +5V on the Harness. Similarly, the buzz was there on the neo cab until I put those on. Is there anything that shouldn't be connected for Jamma that would be for neo geo? I figured that since it works okay on regular jamma boards, it was connected correctly.

Also, the video looks like its too big for the monitor. The bottom inch of the monitor looks like its squished.

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UMK3 has a vertical frequency of 53 Hz, MVS is 60 Hz so the height will need to be adjusted on the monitor.

and it would produce a very large buzz on NBA Hangtime if I didn't connect +5V on the Harness

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You do realise that these Williams boards require the -5 volts to be connected also (unlike MVS)

Is there anything that shouldn't be connected for Jamma that would be for neo geo?

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Its mostly to do with the sound. Jamma has a speaker connected across L and 10, whereas MVS is wired like this

You do realise that these Williams boards require the -5 volts to be connected also (unlike MVS)

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Oh, okay. I knew +5V had to for Midway boards, but not Jamma, I was unaware of the -5V being absent on MVS. However, it is connected. All of the pins for the power are connected.

Its mostly to do with the sound. Jamma has a speaker connected across L and 10, whereas MVS is wired like this

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I believe (not positive, didn't trace it all the way because of the way its routed) that they are hooked up correctly for Jamma sound. That's just a guess though, since other Jamma boards work with no sound issues at all. There are a few pins not connected, I just looked them up now, and they seem to not need to be connected (according to the pinouts on NBA Hangtime, which again, is the same hardware/board, with different ROM chips). I crossreferenced this with standard jamma pinouts, and one pin that is labeled "Audio Ground" is not connected! This may be the problem, but it says that its not used in the NBA Hangtime manual, and it doesn't cause any problems with my other boards by not being connected. I can try to connect this pin to ground tomorrow, maybe I'll find something.

UMK3 has a vertical frequency of 53 Hz, MVS is 60 Hz so the height will need to be adjusted on the monitor.

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This, I was totally unaware of. I tried to adjust the monitor, however, using the monitor controls underneath the control panel.... Okay, just tried it again, and I'm kind of dumb, haha. I thought that I tried it to each limit (max/min on vert pos and size), and I did, but I didn't notice that it helped quite a bit. So this part of the mystery is closed. Thanks, I don't think I would've tried that again if you didn't say that. I think what confused me is that the characters feet on UMK3 look kinda squished in the first place. Its not 100% fixed (at the vs screen, I can notice minimal squishing) but its a lot better than before, thank you very much.

So, the sound issue is the only problem I'm looking at now. Thanks for the help so far, I'll let you know how it goes.

ChairHome said:

I believe (not positive, didn't trace it all the way because of the way its routed) that they are hooked up correctly for Jamma sound. That's just a guess though, since other Jamma boards work with no sound issues at all. There are a few pins not connected, I just looked them up now, and they seem to not need to be connected (according to the pinouts on NBA Hangtime, which again, is the same hardware/board, with different ROM chips). I crossreferenced this with standard jamma pinouts, and one pin that is labeled "Audio Ground" is not connected! This may be the problem, but it says that its not used in the NBA Hangtime manual, and it doesn't cause any problems with my other boards by not being connected. I can try to connect this pin to ground tomorrow, maybe I'll find some

So, the sound issue is the only problem I'm looking at now. Thanks for the help so far, I'll let you know how it goes.

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These games are standard jamma mono, just connect a single speaker across jamma pins 10 and L, do not ground one side of the speaker.

Just for the record, the vertical frequencies
MK/NBA Williams 53.20494 Hz
Neo Geo 59.1856 Hz

Thanks for all your help. Just wondering, do you know what other standard jamma games output at? I thought it was 53 Hz as well. If this is so, it confuses me as to why these games wouldn't fit and others would.

So, I would connect L and 10 to just one speaker, and not ground it? Leaving the other speaker disconnected, correct?

ChairHome said:

Thanks for all your help. Just wondering, do you know what other standard jamma games output at? I thought it was 53 Hz as well. If this is so, it confuses me as to why these games wouldn't fit and others would.

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Most are 60 Hz, if you use a mame front end you will see the freq, number of buttons, orientation etc listed. Which is usefull for reference.

So, I would connect L and 10 to just one speaker, and not ground it? Leaving the other speaker disconnected, correct?

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Yes, or you could wire in a switch to connect both speakers in series between 10 & L.