MVS Slot-1 Odd wiring...

Some time ago, I got a MV-1 board in a cabinet (along with a pop'n'bounce cart) second hand. I noticed some of the buttons wern't working normally on the test page, but because PnB only used one button, I didn't attempt to fix it.

Now I have KoF96 in there, I notice that both D buttons don't work, and that the board has been wired oddly.

I've taken a photo you can see at
<a href="http://www.lavalamp.demon.co.uk/oddwires.jpg" target="_blank">http://www.lavalamp.demon.co.uk/oddwires.jpg</a>

In that photo, the red goes to parts side pin #25 and the black goes to solder side c.

So someone has wired P1 D+ into the 5volt rail and soldered P2 D+ into ground. There are wires coming off the microswitches on the panel,but they lead nowhere.

Can anyone shed light on why they would do this, and seeing as the board works (other that no D button) if they think it's safe to undo
this.

Thanks in advance
Andy

Wow that is horrible...de-solder the wires and then reconnect them were they belong on the jamma harness. If you need help locating the correct spot to solder on the harness go to <a href="http://www.hardmvs.com" target="_blank">www.hardmvs.com</a>

Yeah, I'm amazed it works. I'm so amazed at it, I'm almost afraid to remove it! I can't think of any reason someone would need/want to make such a mod to the harness.

It's even odder when you consider it's soldered from the board back into the harness. If I was doing that, I'd have just joined the connectors together on the harness.

Unless anyone can think of a reason to keep it, it's coming off this weekend! <img src="graemlins/veryangry.gif" border="0" alt="[Very Angry]" />

Hey Bowdie!

"So someone has wired P1 D+ into the 5volt rail and soldered P2 D+ into ground."

Do you mean that those Red and Black wires go straight from the motherboard (shown in the pic) to the JAMMA harness? Or, do they go from the motherboard up into the control panel of the cabinet?

The only thing that I can immagine is that whoever wired this up wanted to light a light or something like that, so they just used the (currently unused) D button wires instead of running new wires. And, it probablly was easier for them to solder onto the MVS PCB than to solder onto the JAMMA harness.

Though, just because it's easy doesn't mean it's smart.

I would snip those wires off as close to the PCB as possible. Depending on how good you trust your solder skills, it might not be worth desoldering the wires. Once you snip them, then try the button-test page again.

That +5 and ground going into those D buttons is VERY odd. I hope it hasn't ruined anything.

Also, your picture would be more helpful if we could see where those wires went. Maybe zoom out a bit and post another pic.

I just noticed that you had a zoomed out pic at <a href="http://www.lavalamp.demon.co.uk/" target="_blank">http://www.lavalamp.demon.co.uk/</a> but it's really hard to follow the wires. It sure seems like there's a lot of yellow wires there. <img src="graemlins/loco.gif" border="0" alt="[Loco]" />

Flavor :

Yup, those wires connect to the spade terminals you see in the pic of my website, and then are soldered directly onto the tags on the jamma connector.

Weirdest thing I've seen for a while. My solder kung-fu is reasonably good, I've mod chipped stuff in my time, so I'm sure I can get those wires off the board safe and sound.

I'm just not sure wtf they're there in the first place!

I've taken another pic at <a href="http://www.lavalamp.demon.co.uk/wire_odd.jpg" target="_blank">http://www.lavalamp.demon.co.uk/wire_odd.jpg</a>
Follow that yellow wire!

Love the smiley, that's pretty much what I did when I saw it!

Thanks for your help
bowdie

Well, it's hard to tell, but it looks like the black turns into blue (at the spade) and then goes to the JAMMA connector. Is that the only wire that's connected to that JAMMA pin? Is the same true for the red that turns into yellow?

If you disconnect those spades, does everything function correctly? Well, except for the fact that you'll still have no D buttons.

I'm not 100% sure, but if I remember right, offhand, you just ground the D+ line when you press a button. You should check out the <a href="http://www.hardmvs.com/manuals/JammaLabels.zip" target="_blank">MVS JAMMA Harness labels from HardMVS</a>. That might help you wire it up. You should also check out the <a href="http://www.hardmvs.com/html/basicHarness2.htm" target="_blank">HardMVS wiring project</a>.

Anyway, it shouldn't be hard to wire up the D buttons. The best thing to do is to unplug those 2 spades ASAP!

>Well, it's hard to tell, but it looks like the black turns into blue

Yeah, black to blue and red to yellow.

>Is that the only wire that's connected to that JAMMA pin?

Yup, they're on their own soldered into the jamma connector.

>If you disconnect those spades, does everything function correctly?

I've not tried it yet, I was hoping someone knew of a reason they're wired like this!

Everything else works aok, some of the buttons are wired NC instead of NO, but that's not a problem to put right.

>The best thing to do is to unplug those 2 spades ASAP!

I agree, unless I read otherwise, they're getting unsoldered at the weekend.


cheers
bowdie

And they're off!

Both wires removed, and the board works fine!(after I had repaired the tracks underneath the solder)

I was so happy, I fitted a stereo kit while I was there! Anyone notice how the drive end of a CDrom audio cable fits snugly onto the connectors of the 1F's speaker connections?

Both D button contacts work ok, all I have to do now is workout how the rest of the buttons have been wired, P1 B closes P2 C and so forth.

But for now I'm a very happy guy, thanks to both RATM and Flavor! <img src="graemlins/glee.gif" border="0" alt="[Glee]" />

Good news. I'm glad it worked out.

[Anyone notice how the drive end of a CDrom audio cable fits snugly onto the connectors of the 1F's speaker connections?]

I wondered what would fit that. I'm going to do something similar in the near future, myself.

Yeah, it's a spot on fit, I'll take a photo of my finished job. It seems to work ok.

Well, the stereo kit was a complete success!

You can check it out at

<a href="http://www.lavalamp.demon.co.uk/ng_stereo.jpg" target="_blank">http://www.lavalamp.demon.co.uk/ng_stereo.jpg</a>

Like I said, it's a CDrom audio cable run out to two phonos and then up to a pair of speakers.

Works a good 'un, the drive connector fits like it was made for it.

BTW : Check out the scars from those wires!