Mysterious Naomi 2 GD ROM behaviour

PCB problems and fixes
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Mysterious Naomi 2 GD ROM behaviour

Post by zeromiles » January 2nd, 2019, 11:14 am

Hello there,

I recently set-up my Naomi 2 + GD ROM setup, played a few rounds of CvS 2 and turned it all off. Half an hour later, I tried to turn the system on again and...

- It boots up, recognizes my net/gd DIMM,
- says "checking memory" (starts at 31%)
- then begins to load the game (drive spins, seeks, reads, etc)

And then reboots to an ERROR 25 - CAN NOT ACCESS GD-ROM DRIVE screen.

I've throughly cleaned everything, checked my +5v, 12V and 3.3V, they all seem to be OK.
I've tried using only the ATX PSU (that juices the GD ROM) for both the Naomi 2 AND the GD, and the behavior stated above occurs.
I've tried using two PSUs (one switching power supply for the I/O and Naomi 2, another one just for the GD ROM) - this gives me a "GAME IS NOT ACCEPTABLE BY MAIN BOARD"

Yes, I tried changing the game for another one (VF4 Final Tuned), same deal.
Yes, I tried playing a cartridge game (MvsC2), and everything is fine.
Yes, I've checked all cables, voltages.
No, I did not hook up the GDROM power harness the wrong way (mine is "keyed", it cannot be plugged upside down).
All tests I could run from the Naomi 2 BIOS seemed to be OK.

The only different thing I did recently, was replace the GD-ROM's fan for a new one. My GD drive is totally different (inside, at least) to this one: I believe it's working properly, because it is oriented the right way and it is spinning freely.

I'm not 100% certain, but I think the original fan had a 3-pin connector with only the red (12V) and black (Ground) wires, while the new one has all 3 wires (yellow, for the tachometer/fan speed function).

Any tips? This is driving me nuts, I can't seem to pinpoint the problem.

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Re: Mysterious Naomi 2 GD ROM behaviour

Post by nem » January 3rd, 2019, 3:19 pm

Does the fan you installed work? If you have power going to the drive the fan should blow out air.

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