Help with 138-in-1 mvs cart

incrediblehark

New Challenger
Joined
May 3, 2006
Posts
64
So I have a neo geo 138-in-1 cart. these are the ones with the sub board connected. I have it connected to an mv-1 board in a cab.

The problem I am having is when everything is connected and I plug in the cabinet, I get a garbage screen displayed which is supposed to be the selection menu.

If I disconnect the jamma harness from the board, plug in the power to the cab, and then connect the jamma back to the 138-in-1, it works fine. I would like to be able to power on the machine and play without having to do this step of reconnecting the jamma cable first. Anyone else had this issue? Or any idea of what I could do for a solution? I will upload pics later of the symptom I am describing.
 

Xian Xi

JammaNationX,
15 Year Member
Joined
Dec 1, 2005
Posts
27,748
Are you actively plugging in the JAMMA harness when the cab is powered on? Only thing I can think of is that maybe your power supply is failing.
 

incrediblehark

New Challenger
Joined
May 3, 2006
Posts
64
Yes, when i plug the jamma harness in while the cab is powered on, I am able to get the cart to work.
 

incrediblehark

New Challenger
Joined
May 3, 2006
Posts
64
This is an old picture, but this is what the screen looks like if powered on while connected to the jamma harness:



Thanks for the suggestion Xian Xi, I'll see about swapping the power supply out. Originally I was wondering if adding a switch somewhere would help.
 

Zellez

King's Dry Cleaner
Joined
Dec 6, 2010
Posts
377
Having the same issue on both my cabs. A New Astro City with an M1 and Japanese bios and on a Megalo 410 with M1 and Western bios.
Tried to plug the 138 in 1 Jamma harness when the cabs are already on, and the screen becomes fine.
Is it replacing the power supply the only solution? Never had any power issue with those two cabs before.

Thanks
 
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ovalfastlx

Kuroko's Training Dummy
Joined
Jul 30, 2017
Posts
78
Having the same issue on both my cabs. A New Astro City with an M1 and Japanese bios and on a Megalo 410 with M1 and Western bios.
Tried to plug the 138 in 1 Jamma harness when the cabs are already on, and the screen becomes fine.
Is it replacing the power supply the only solution? Never had any power issue with those two cabs before.

Thanks

Did you fix the problem? for some reason I can't see the image you posted. I was getting a green screen (garbled) on game boot ups with the same cart. I ordered a new arcade PSU, that should come in soon, before that I was using a computer PSU. Will look forward to an update.
 

Kingen

n00b
Joined
May 4, 2018
Posts
13
Has anyone found a good solution? I have two Sega Blast City cabs, Tried many different things on both of them, PCB, NAOMI etc - nothing is failing except my two 138 in 1. If I don't use the PCB it works, but then I end up with the first game obviously. The "Hot plugin" works (ie starting the cab without connecting anything to JAMMA and then after a while plugin the PCB while the CAB is on) i'm afraid to kill my cabinet or the NEO GEO by doing that and its not as efficient as it could be.
 

incrediblehark

New Challenger
Joined
May 3, 2006
Posts
64
Hey, sorry for not replying to this sooner... I actually just started getting back into neo and I'm getting ready to tackle this problem again. I never did order a new psu but Zellez's post makes me wonder if that would necessarily solve the issue. I have a few ideas in place im going to mess around with and hopefully I'll have a follow-up post here soon.


EDIT: Well I killed the daughterboard... Was hot plugging the jamma connector to the daughterboard when I got a pop and the magic smoke...

I was working on setting up a timed relay to switch power to the board a few seconds after power on which was promising but after this I can't do much more. I finally got around to ordering a Unibios, and going to go the route of 161-in-1 with PickNMix, and get a dip switch board for the 138 to play the games not on the 161. But I definitely don't recommend hot plugging the board as a workaround.
 
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