Capcom I/O give "Jamma I/O board not found"

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Capcom I/O give "Jamma I/O board not found"

I have a Capcom I/O that give me this error. I am using a Naomi 1 and a MvC2 cart and a net boot setup. I have adjust the voltage from 4.9 to 5.15 and I still get the error. Out of every 10 try it boot up once. I have use different sub cable and have clean the edge. On my other Capcom I/O it boots all the time. Any ideas?
 
voltage won't matter in this case. never go above 5.10V on NAOMI. (read the end of my PSU guide in my signature for more details on measuring voltage on NAOMI)

I never got into netbooting with these, but I'm not sure if it's just you can't run a GD-ROM with Capcom I/O or netboot as well. I'm not entirely sure why it would even know if it's a Capcom I/O (the error message), do you have the USB cable connecting from the NAOMI board to the Capcom I/O?
 
Just the I/0 being change out, that's the weird part. It power the Naomi fine, boot the cart too. It goes to the game is for Japan only screen (Japanese bios) then I get the error. My other 2 I/O are the Japanese version? Has Japanese warning sticker (I assume the internal all the same) I even power the Naomi with a sun psu so the I/O only handle the I/O part and I still get the error. I even clean the usb contact with some deoxit just to make and no change. This one a head scratcher.
 
I actually had the same exact issue with the same parts: MvC2 cart, Capcom I/O, NAOMI. Seems one of my cabs had a faulty PSU. I switched my NAOMI to another cab, dialed in the 5v and 12v and the I/O error went away.

If using a Dimm/NetDimm, you cannot power the NAOMI through the JAMMA edge with the Capcom I/O. You must have a dedicated PSU connected directly to CN1 and CN2. Also, make sure you have the Capcom I/O set for 2players not for 4 players. There is a switch inside the opening where the JAMMA edge is located.
 
The new psu was in hope that the 1 I was using was not up to spec. I think it's an I/O problem as even power the Naomi with a SUN psu still give me the problem
 
You did say that you are using an MvC2 cart in a NetBoot setup? This is kind of not possible. If you are using a MvC2 cart, then of course, you can't be NetBooting. Netbooting requires a NetDimm in place of the cart. Do you mean, you are using a NetDimm and are NetBooting MvC2?

In any case, make sure you use an external power supply that has 3.3 volts. Dial in your voltages exactly like mecha recommends in his signature link. Also, be sure to connect power through CN1 and CN2. You will still have to power the Capcom I/O as well from the JAMMA edge. But do not power the NAOMI from the Capcom I/O in that setup. If you have done all this, safe to assume your Capcom I/O is cooked. Perhaps try replacing the capacitors to fix it. In the link I provided previously, I was able to resolve the same issue by switching to another cab with another PSU. But of course, I have plenty of other cabs and PSU's. You might not have this luxury. Good luck bro; let us know how it goes.
 
I did it both way. Cart first, which gave me the error. I then move over to the net dimm just to rule out a bad cart, same error. I have used 2 different psu for the I/O and 2 different SUN psu for the Naomi (CN1 and 2 are connected). My other Capcom I/O run fine with this setup or just powering the Naomi off the I/O. Next step for me is shot gunning the caps
 
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Yeah, sounds like it's bad then. If it works with another Capcom I/O on the same PSU and setup, then the only factor is the I/O board itself.

I'd say give it a thorough cleaning before you do the cap replacement. Like remove any EPROMS, give it the Simple Green wash. Use an eraser on the JAMMA edge, then if that fails, cap it/probe it/or whatever other options you got. Retest, then take it to the OR for the next steps.
 
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Well, I finally fix this thing. It turn out to a solder bridge on the underside of the board. Pin 1 and 2 of the SOT-25 step down converter. From what I can tell its been there for awhile (factory maybe?) as the solder is dull like the rest and there is no flux residue. It would always boot on a cold start and fail on multiple reboot.
 
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