Sega-Naomi

Summary (more details below)

-Getting Error 01 on MVC2 cart

-Cart WAS working until I pulled it and reseated (noob just trying to learn and diagnose sound issue)

-Unknown Title in test screen & ---- during game ROM check



I just bought a MVC2 arcade machine that has a Naomi system in it. The monitor was on its way out (colors messed up) and no sound. I was working on diagnosing the sound issue and think I should have been plugging into the stereo out on the Jamma converter, but I had just tried plugging the audio output of the Naomi directly into the line in of a boom box just to try it). Really not sure if at that point I should have heard anything or not but I didn't. So at that point game still worked but without sound just like it always had.



Anyway, I'm new to all of this so I figured I'd pull the cart out (turned machine off first) and reseat it to see if that made any difference, plus learn how the carts were removed. After replacing the cart I got an Error 01 and when going into test mode is says "Unknown Title". The cart's rom chips all read ?? for type and ---- for Result. So I figured easy enough, pulled cart, pushed back in, no go. Incidentally the Naomi system's ROM check has always said GOOD for everything.



Once in a while it will make it past that screen to a black screen, then after a few seconds it's as if the monitor cable was pulled.. like if you started the machine without the Naomi connected. At that point hitting test button doesn't boot it into the system test menu.



I've looked at the connections and don't see any bent pins. I blew them out with spray of air. I opened the cart and blew out some gunk the air vents on the cart case let accumulate. I must have tried the cart like 100 times by now and haven't gotten it to boot the game. I don't have any other carts I can try unfortunately. I tried putting a little pressure on various parts of the cart while booting up just to see if it was a loose connection. I tried suggestions I saw here of "Backup Data Clear" and did that probably 10-15 times. Also tried the cart pcb without the case to be sure it was fully seated in the connectors.



I'm very bummed right now and just in aww how quickly something broke. I'm usually pretty careful figuring out how to remove things nowadays and only thing I can think of is I sort of wiggled the cart back and forth to get it out but I feel like I was fairly careful while doing that.



Voltage measured at power connector to Naomi while on the Error 01 screen shows 3.31v, 5.10v, 12.49v. I was also able to find 5.08v on one of the outer game rom chip pins. So the cart seems to be getting power.



It looks like this forum has a lot of very knowledgeable people and was really hoping someone could help me diagnose the issue. Main thing seemed to be "Unknown Title" and game ROM check not coming back with anything -- versus if it was coming back with bad roms.



Thanks for any help or ideas!



-Wayne





**Update**

Okay I opened up the Naomi system case and found a burnt trace near the RCA outputs that would explain the "no sound" issue. The trace leads to a blue component (see pictures below) -- is that a resonator?? I think this was the pre-existing condition of no sound.. so at least now I don't feel like a complete bonehead trying to take the cartridge out and reseat it to eliminate that possibility. Continuity test shows that both RCA plugs have one pin that connects through that trace. The other two blue resonators?? beep on the remaining RCA pin for their respective left/right RCA plug.



http://www.techdose.com/temp/burnt_trace1.jpg

http://www.techdose.com/temp/burnt_trace2.jpg

http://www.techdose.com/temp/burnt_trace3.jpg



I don't see any other issues with the board that would explain why the cartridge stopped working though.

That blue part is an EMI/RFI filter. Check it for continuity between the 2 outer pins... and make sure there is NO continuity to the middle pin.



If there are no bent pins on the cart then maybe you have some blown buffer ICs on the cart. Those are the tiny tiny ones with about 40 hair thin legs on them. You'll find a bunch of them on the cart.



Do you have another cart to test the board with?



RJ

Hi RJ,



No other cart.. I know that'd make things significantly easier to isolate the issue -- I wish there was a cheap game I could buy and try.. or borrow a game to confirm.



I saw some of your posts about those buffer ICs -- was really hoping that wasn't going to be the case. Is there anything I can check to verify if it's those? Could they produce the situation where the cart is not recognized at all and doesn't give any readouts on the cart's rom check?



As for the EMI/RFI filter, there's continuity between the outer pins but not the middle pin as you mentioned. I checked the other two as well and they work the same. There's also continuity between all the middle leads.. which looks to be ground.



I'm wondering if I should be concerned about the pins beneath the connectors on the motherboard/cart? I don't see any of the pins inside the connectors bent, but it looks like the connector pins pass through to the other side of the board on both PCBs. Is it possible to unclip both sides of the connectors and view those pins?



I cleaned up the motherboard and cart with a air & then lightly brushed anything remaining with a dry tooth brush. I don't have any 99.9% alcohol but I do have flux remover spray.. but haven't used that yet. Just figured I'd see where just cleaning the worst off the boards got me -- unfortunately still at "Error 01" and "Unknown Title", but with slightly cleaner boards.



-Wayne

The easiest way to tell is to swap carts. The connectors on the cartridges that Sega used are fickle and are a huge PITA, but are "generally" OK if they look good.



A similar connector is used on some multi-board Konami games, but since those aren't in plastic housings like the NAOMI is they tend to not last as long as the ones on the Sega system.



If the filter tests good for continuity (which it sounds like it is with your description of it) then solder a jumper wire to replace the burnt trace. That won't fix your cart problem though.



The buffer chips are not easy to test thanks to the way the boards are sandwiched together. It's easier to replace them than to test them IF you have the surface mount soldering equipment.

channelmaniac-



Ok, got another Naomi 1 System + cart (virtua tennis) off eBay. The MvC2 cart still gives an Error 01 with the new system (same bios version in the system I believe), whereas the Virtua Tennis cart booted fine in the new system.



Wondering if it could possibly be any of the plate throughs like you had experienced on one of these carts. I just don't get how pulling a cartridge out and putting it back in did something.



I took some voltage readings on the cart's EPROM and wrote down the values next to the pins in the datasheet (see pic below):







I guess what I'm wondering is what the sequence of events are when the Naomi is looking for a valid cart -- I've yet to find even a rather simple explanation of how the cart is checked to be valid, region loaded, how chips are transferring data. There seems like there should be a higher level way of narrowing down the issue on the cart and not just assuming the buffer ICs are the culprit and replacing them?? Or am I just wishfully thinking?

acebh wrote:Or am I just wishfully thinking?

That I do not know. What I do know is that what you are trying to troubleshoot far exceeds my knowledge of the Naomi, and that of many others, I believe..



Unless you have/know the exact architecture of the Naomi's cart electronics and its software, there is little to no use in troubleshooting, imo..

The most common things to go wrong on Naomi carts is either the buffers (anything over 5.25 can start to cook them), the occassional mask rom, the security chip and very, very rare the eprom.



The other big problem is the IDC connectors, bent/broken pins, pins not making a good enough connection.



Also be careful where you bought your MVC2, there where a number of dead ones which weren't even MVC2, they had the plastic case, but the roms etc was not MVC2

AndyGeezer - yeah, I know this cart was a valid MvC2 cart since it was working just fine up until I popped the cart out and put it back in (aside from no sound issue I was trying to diagnose). Sound issue turned out to be burnt trace on filter board + possible damage to other audio components. I have a new Naomi that works fine, but MvC2 is still giving ERROR 01 on that. So cart worked, then died on me without much of a reason.. trying to diagnose at a high level what it could be. Have no isolated it down to just the cart I think. I would think "Unknown Title" and not recognizing any roms should help indicate either pins, buffer chips, other dead chip or voltage not getting somewhere that's needed to further isolate down to the actual issue. Pins look fine on cart though.



If I plug the cart into the opposite side of the Naomi board, should it work that way too? Seems like the connectors would allow you to do that.