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[Repair Log] Sega Naomi

Hi, I just started replacing every ram pair and when I replaced 116/118 that fixed it. This was for a Naomi 2.

They are very easy to replace.

Note that I was using the old multi bios. Possibly that bios has a buggy ram test (it's based off an old bios revision). If you are using the multi bios, try the ram test using normal bios latest revision.
 
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MickyMac said:
Hi, I just started replacing every ram pair and when I replaced 116/118 that fixed it. This was for a Naomi 2.

They are very easy to replace.

Note that I was using the old multi bios. Possibly that bios has a buggy ram test (it's based off an old bios revision). If you are using the multi bios, try the ram test using normal bios latest revision.
Click to expand...
Exactly those to were gone on the last 2 Naomi's I repaired. So I can confirm that this maybe a common issue: It boots very slow and has graphical glitches.
 
I'm attempting to fix a N1 that boot slow. Freeze before finishing ic09. I have replace both ic09 and ic11 to no luck. Will a video ram cause the same issue on a N1? I don't have any on had and don't want to swap from my parts board as I don't know if they work.
 
Try IC16+18. Last one IC 16 failed but showed okay during ram test and did the slow boot shit you mentioned. N1. IC was already placed so I wondered why I got the slow boot. I guessed it's 16 and I was right.

Buy a few of the ics. Handy to have em stocked. I wouldn't gamble with the ones from the parts board.
 
Thank, I'll see if I can find any compatible ram to steal from or gamble on Aliexpress.. In the mean time I'll swap from parts boards and see what happen.
 
MickyMac said:
They are just old pc100 sdram. I got mine from an old ram dimm.
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I have a bunch just non of them match the configuration. Mostly 4mx4 and 2mx8. I want to confirm ram grouping is left to right and not up and down going off the ram test screen
 
Hi, my Naomi 2 with GD-Rom setup is giving me headaches. Used to work but it now freezes on boot, or boots into "System initializing" (not memory check) and freezes or gives me straight up a error 22 message ("Communication error occurred between main board and option board"). I think I can hear the GD-Drive spinning up, but from the Naomi 2 to the PSU, everything is quite loud.
Any suggestions as to what could be the cause or what else I could test?
Thanks
Naomi 2 is in a Naomi Universal cab, original PSU. Original BIOS 23608, swapped with 23608-A. GD games Virtua athletics, works with 23608, GGXX Slash, worked with 23608-A. Cartridge Virtua Striker 3, works with 23608. I have 2 GD-Drives, I get the same result with both.

I have tried the following to narrow down the possible fault, all results as expected:
Run cartridge with jap BIOS (Error 21).
No Dimm board (Error 01).
With Dimm but not connected to GD-Drive (Error 25)
With Dimm, connected to GD-Drive, but GD-Drive not connected to power (Error 25)
With Dimm but cover GD-Drive cover open (Error 23)
With Dimm, GD-Drive cover closed, no game (Error 24)

The did the following tests in the test menu:
Tested RAM without cartride, all good.
Tested ROM board, all good.
Tested Dimm board without game (prog. ver. 1.02, all good except Dimm status = bad and GD Drive bad).
Tested Dimm board with game, I get a Dimm board time out message and "Unknown game" is displayed in test menu
confused.png




 
After a good week of research of what could be the problem and what to try out, I measured the voltage of the setup under load. To do that, I had to remove the cover from the mobo and dimm board. To my surprise everything operated without any problems (yes, really).
I put the Naomi 2 back in its case but not the dimm board and now the setup works again. I'll leave it that way.

P.S.: The BIOS I tried with GGXX was a 23605B (japan) and not a 23608A (export) as stated in my previous post.
 
I’ve got a similar issue with an N1 with no video or audio. And without schematics it’s pretty tough to work these issues out. Hell I can’t even find a pinout for the bios chip. I’ve reflowed all the chips except what is under the hsf and heatsink and recapped the whole board. Not sure what else to do without schems.
 
Casselfornia said:
Sounds like bga issue. Bios traces look good?
Click to expand...
Yeah, I don't see any physical issues with the board. All the chips are receiving 5 and 3.3v but they just aren't getting hot. And the 2 heatsinks aren't getting warm either. The board acts like it should be on, but nothings happening. Full recap and full reflow and still nothing. After replacing the super cap I got hum in the speakers again as if they were gonna turn on, but that's all. So yeah, all I could think of was either the gpu or the cpu at this point. Depending on the amount of the bga needing reballing I do have the tools to do it. Also helps if there is a stencil for it.
 
Make sure the fan on the motherboard is good and spinning. The Naomi won't boot if the fan isn't spinning properly. Also look closely at the supercap next to the battery. If it looks oily on the PCB around it or if its solder joints look dull or crusty then it is leaking. That electrolyte will damage the traces under the 8 pin EEPROM socket first then spread out to the 32k x 8 battery backed RAM (IC29, IIRC) and / or under the BIOS socket, depending on how the board is mounted in the cab.
 
Hi! :)

I can't find the RAM (IC106 and IC107) on my Naomi 1 motherboard ?(

Is this Ram location only on Naomi 2 :?:

Thanks You
 
I don‘t remeber if those are on Naomi 1 but make sure to check both sides of the board for the silkscreened numbers. Do they show up as bad in the memory test?
 
Hi all,

Can I use any SCSI cable to connect the DIMM board with the GD-Rom drive or is the wiring for the Naomi special?
Are there any known compatibility issues between Naomi BIOS and DIMM firmware version (e.g. BIOS ver. X does not work with DIMM fw. ver. Y)?

Thanks.
 
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