NAOMI GD-ROM Help

[Madgear]

I'm sure the loom is fine. You're measuring wrong somehow. If there was no power there, the system wouldn't boot at all.

What's happening on screen when you're measuring? Is the system sitting at Error 25?

That makes sense. I’ll try again—but yes, it sits at the Error 25 screen.

[Madgear]

Alright! Re-measured, and you’re right @nem - I think I wasn’t near the root of the connection enough. The new values I have are:
Red: 11.7
Yellow: 4.9
Brown: 3.1

And it is now displaying “Error 24: GD-ROM is not found.”

[nem]

Your 3.3V (brown) is very low and could be the reason why it's erroring.

I'm not sure what kind of a DC-DC converter the Capcom IO uses. I assume it uses 5V for the stepdown? Try raising the voltage 5V on your PSU and see what happens. Measure the +5V (yellow) on the filterboard while you adjust, don't go over 5.1V.

Re-measure 3.3V when you've done adjusting. Hopefully you're closer to the target. Try rebooting.

[Madgear]

Oh wow- crazy how that happened, as I had success before. How is it that the voltage can lower? Did I trigger this in some way? I’ll be honest, I’ve got alot to learn about working with the PSU, and electrical stuff, so I’ll do some studying and try your solution out! Many thanks for all of your advice @nem

[nem]

When the voltage is low it can be temperamental, sometimes it works, sometimes it doesn't.

A dimm board consumes more power than a regular game cartridge. That's why you never had any issues with those.

[Madgear]

Makes sense! Naomi with GDROM is really something, huh? Thanks @nem

[729]

Would having your 3.3V set too low on a Sun PSU (while 12V/5V is set correctly) cause certain NAOMI cartridges to hang indefinitely at the “Loading Game” or crash on the Attract Screen?

I don’t want to point full blame at the game cartridge yet, but maybe it’s PSU related? Everything else like DIMM/GD-ROM and other cartridges run as intended though.

[nem]

Would having your 3.3V set too low on a Sun PSU (while 12V/5V is set correctly) cause certain NAOMI cartridges to hang indefinitely at the “Loading Game” or crash on the Attract Screen?

I don’t want to point full blame at the game cartridge yet, but maybe it’s PSU related? Everything else like DIMM/GD-ROM and other cartridges run as intended though.

It's possible. See this recent post on Arcade-Projects:

https://www.arcade-projects.com/threads ... ost-450835

For the record, you can cook carts with overvolting. I did it with Zero Gunner 2 and a DIMM cart. So don't go overboard, or if you do, drop the voltage for anything else except the problematic cart(s).

Ideally you want to measure from the test points on the PCB. There can be a significant voltage drop from the filter board to the PCB.

[729]

For the record, you can cook carts with overvolting. I did it with Zero Gunner 2 and a DIMM cart. So don't go overboard, or if you do, drop the voltage for anything else except the problematic cart(s).

A few days ago, I came across mecha’s “Essential PSU Guide” to get a better understanding and proper practice on handling NAOMI voltages. I felt there was probably more to it than just “plug and play” with a Sun PSU compared to handling JAMMA PCBs.

My goal ranges I’d want my PSU to output:
5V: 4.95V - 5.00 [never above 5.10V]
3.3V: 3.30V [exact; higher for questionable cartridges]
12V: ~12.00V

Would having your 3.3V set too low on a Sun PSU (while 12V/5V is set correctly) cause certain NAOMI cartridges to hang indefinitely at the “Loading Game” or crash on the Attract Screen?

I don’t want to point full blame at the game cartridge yet, but maybe it’s PSU related? Everything else like DIMM/GD-ROM and other cartridges run as intended though. :eh:

It's possible. See this recent post on Arcade-Projects:

https://www.arcade-projects.com/threads ... ost-450835

Wow that’s such a strange occurrence; very interesting read though. My close friend is an electrician so we’ll take a look at the 3.3V readings (and others) to see what happens soon. If the game is still wonky, I may have Ken take a look at it next month.

[Madgear]

This is all very interesting, going to read up on that guide now…

While I’ve got you all here, any idea what this is?

Picked up a Naomi board and Cart, for a good deal off of ebay- the cart wouldn't work with this board, but did with my other one. (So cart is all good)

Board gives a weird display, and error 01
Looks like this- unable to fill screen, generally darker also

IMG_5605.jpeg