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Jul 21, 2015
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Hi guys long time lurker with a Sega naomi Net dimm problem here.
I had an running Naomi 1 with a 256 MB 3.17 Net Dimm until on day last Year it shows Error 22 on Boot. A quick search reveal the devastating possibility that the communication Board died. By then I had no time so it sits on my bench until today.

On my bench sits a different naomi Mainboard with BIOS Labeld ERP-21576H and it shows the Network Settings in the Test Menu.
From a Universal Naomi a 230 V Ac Transformator to 110 V Ac then strait into a OG Sun Power Supply and with 6 and 8 Pin Connector connected to the naomi.
The Naomi works without a Game, all Rom check out. IMG_20230328_151158.jpg
The voltages were a little high with 5.2V and 3.4V but no card was present.
For testing I got my trustworthy Virtua Tennis and it's boot to the IO not connected screen. Test Menu is fine.

So my Mainboard works let's plug in the net dimm and adjust the voltages on the Comm Board. 3.307V and 5.05V under load. Messured on the pins of the zero PIC.
The net Dimm boots with Error 22, nothing new.

A RAM swap show quickly that on of the Rams was dead. With one RAM in slot 1 (the one closest to the edge) I got Error 34. With the other Ram I got Error 32: Dimm Memory is Not enough.
So let's roll with on 128 MB in slot 1 and Error 34.
Dimm Check came out Good with version 3.17.

IP Settings fixed and Network test:
IMG_20230328_164049.jpg IMG_20230328_155540.jpg
I changed the IP to connected to my router with same ip range and subnet. Followed by a hard reboot.

So far so good. On Boot led 3 (out of the four on the comm board) flashes green really quick one or two times.
The bad news is my router doesn't recognize the net dimm as client nor does he even see a connection on the Lan port.
From my Laptop I can't ping the net dimm nor can i send games to the ip address.
I tryed Windows with the Transfergames.exe and Linux with the python script. No luck here ether.

I have buffer replacements 74LVC16245A TSOP48 on the way but now I am out off ideas. Anything I missed or can try?

A friend of mine has another working net Dimm and he is willing to swap the comm Board for testing but this will happen in the next one or two weeks.


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Follow up. I got a net dimm from a friend begin to swap some parts.

First control run:
My dimm, my comm board = Error 34
Friend dimm, friends comm board = works like expected

My dimm, friends comm board = works like expected.
All 4 leds blink on power up, led goes solid green, led 2 goes solid red after a few seconds, led 3 blinks from time to time.
Screen shows "checking network" and sending a game works fine after adjusting the ip Adress.

Friends dimm, my comm board = works
I expected Error 34 but instead I got led 1 solid green and led 3 blinking. Screen showed "checking network" and sending works too!

I switched both dimm to the original configuration and my dimm with my comm board works. I could send a game and play!

At home the net dimm goes back into the shell and full of joy I bootet up my naomi just to be greeted with Error 34.

So what's the takeaway? Bad connectors between dimm and comm board?
Parts are still in transit.

Does somebody know the part number or names for the two connector between dimm and comm board? Mouser etc.