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bodgit

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I have a Naomi 2 that doesn't seem to recognise any Net-DIMM that I attach. I've got a few of them with various firmware versions; 2.06, 3.17, & 4.01, and none work.

I was assuming it to be a fault on the DIMM itself (buffer chip?) until I've finally gotten hold of a second Naomi 2 and they all seem to work fine on that system, at least they get as far as displaying an error 33 or 34 about the gateway, which is expected as I didn't bother hooking up a network cable. The Naomi logo also correctly changes to add the "network system" text which it doesn't do on the bad system.

So it seems to point to the Naomi 2 itself as the problem. Observations:
  • I get either an error 01 or 22 on boot.
  • Voltages are all close to their correct values, same PSU also works fine without any changes on the good Naomi 2 so I think that's ruled out anyway.
  • In test mode, RAM checks all pass.
  • Also in test mode, sometimes it can see there's a DIMM fitted, but the version is reported as 0.0 and it times out trying to test it.
  • I've enabled the serial console on the DIMM and can see it booting up so that's getting power.
  • I have a Virtua Tennis (Power Smash) cartridge and that works without any issue.
The Naomi 2 seems to be fairly clean in decent condition aside from the super capacitor has been removed at some point and the larger SMT 100Ω resistor next to it has been replaced with a radial equivalent, so maybe that was a previous repair. The BIOS is also an unlabelled EPROM so I'm going to dump that out and see if it matches anything.

Does anyone else have any ideas I can try?
 

skate323k137

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Most likely the BIOS is an old revision without netboot support; just try a C or multi if you can.

Edit: Just re-read where you said it says network system... that's interesting. Still, running a romident on the BIOS might help you out.
 

bodgit

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I've just tried swapping the BIOS chips between systems as I realised I hadn't tried that yet but it made no difference. The known BIOS is marked EPR-23605C. I think the unlabelled BIOS is supposed to be some sort of multi-region version, it reports "Japan System" in the test menu.

Also remembered that I should mention I've tested with the top half of the case removed so I can see everything is firmly connected together.
 

skate323k137

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23605C Definitely should work, and both Naomi 2 multi region BIOSes in circulation are based off of it.
 

doccaz

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Are the connectors on top clean? Any visible corrosion or damage? Try some contact cleaner on the pins.
 

bodgit

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Out of the two Naomi 2’s, the bad one is a hell of a lot cleaner than the one that works! The connectors all look clean.

It turns out the super capacitor hadn’t been removed, but it has been repaired/relocated to the underside of the board. I suspect it was easier to solder on the top side of the PCB.

Other than the quality of that repair work, there’s no obvious damage or corrosion. The fact that the Virtua Tennis cart works suggests the system is mostly ok, maybe it’s just one of the three connectors that is tripping the DIMM up.

Do some carts use fewer of the pins in those expansion connectors compared to other carts and/or NetDIMMs?
 

doccaz

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So it seems to point to the Naomi 2 itself as the problem. Observations:
  • I get either an error 01 or 22 on boot.
  • Voltages are all close to their correct values, same PSU also works fine without any changes on the good Naomi 2 so I think that's ruled out anyway.
  • In test mode, RAM checks all pass.
  • Also in test mode, sometimes it can see there's a DIMM fitted, but the version is reported as 0.0 and it times out trying to test it.
  • I've enabled the serial console on the DIMM and can see it booting up so that's getting power.
  • I have a Virtua Tennis (Power Smash) cartridge and that works without any issue.
The Naomi 2 seems to be fairly clean in decent condition aside from the super capacitor has been removed at some point and the larger SMT 100Ω resistor next to it has been replaced with a radial equivalent, so maybe that was a previous repair. The BIOS is also an unlabelled EPROM so I'm going to dump that out and see if it matches anything.

Does anyone else have any ideas I can try?

One weird behavior I noticed on my Net-DIMM last week was that it did report version 0.0 (but present) and also I couldn't change the network settings (always got a "DIMM Timeout" when it tried to save the configuration). It was working perfectly the week before. It looked like something was corrupted on its flash. I disassembled it at least a dozen times looking for bad contacts or broken traces, all good. It turned out that if I swapped the RAM modules for an older one I had lying around, things started working again. So, I cleaned the DIMM memory sockets and reseated my original memory modules... it's running fine now. Maybe it's worth checking out?
 

nem

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Dimm boards seem to be way more sensitive to power than regular carts. I have three Naomi units that I need to switch off and on (sometimes multiple times) before they will boot up properly. Otherwise they just sit on a black screen.

I suspect this would be fixed by recapping the boards, but I haven't gotten around to it yet.
 

doccaz

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Dimm boards seem to be way more sensitive to power than regular carts. I have three Naomi units that I need to switch off and on (sometimes multiple times) before they will boot up properly. Otherwise they just sit on a black screen.

I suspect this would be fixed by recapping the boards, but I haven't gotten around to it yet.
Sure sounds like it needs recapping. How are the voltages on the Naomi itself? Check the test points with a multimeter.
 

doccaz

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Dimm boards seem to be way more sensitive to power than regular carts. I have three Naomi units that I need to switch off and on (sometimes multiple times) before they will boot up properly. Otherwise they just sit on a black screen.

I suspect this would be fixed by recapping the boards, but I haven't gotten around to it yet.

..... aaaaand... :drumroll: I started getting exactly the same error here just a few moments ago. Fist of the North Star was loaded and on attract mode for a few hours when it failed. :unsure:
 

nem

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Voltages are fine when tested with a multimeter. A scope would possibly tell a different story, but I don't have one.

I never have issues once I have the games running, it's just the initial boot up.
 

bodgit

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One weird behavior I noticed on my Net-DIMM last week was that it did report version 0.0 (but present) and also I couldn't change the network settings (always got a "DIMM Timeout" when it tried to save the configuration). It was working perfectly the week before. It looked like something was corrupted on its flash. I disassembled it at least a dozen times looking for bad contacts or broken traces, all good. It turned out that if I swapped the RAM modules for an older one I had lying around, things started working again. So, I cleaned the DIMM memory sockets and reseated my original memory modules... it's running fine now. Maybe it's worth checking out?
As I originally mentioned, the DIMMs work fine on another Naomi so I think they're good. They all pass their tests.

Literally the only thing I'm swapping between things working/not working is the Naomi itself. Same DIMM, same power supply, (which I've checked at the Naomi end and is pretty much spot on, or as close as I can get with the adjustment available).

So with my scientific/engineer hat on, if the only thing changing is the Naomi, that's the problem.
 
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