Naomi 2 mobo repair needed... I think...

GuidoTorpedo

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I have a king of route 66 that has shit the bed. Power supply voltages seem ok, although the +5 is at 5.4, and the 3.3 is at 3.5. Game powers to a blank screen... Nothing, no audio. Tried reseating everything. Fans in the mobo spin.

Does anyone know who can repair this?

Thanks
Mike
 
dude... you probably fried the RAM buffers on it. those boards run extremely conservative voltages, you should really run no higher than 5.05V at the yellow and white wires, and the 3.3 should be exactly 3.30V on the brown and white wires. (yellow = +5, brown = +3.3, white = ground in Segaland(tm))

I just had to change out a power supply on a World Series Baseball (HUGE moneymaker btw /sarcasm) that was giving me like a U29 RAM error and while I'm going through the trouble of swapping main boards and DIMM boards, I check the power supply (which I've been checking once a month for the past year) and the +5 rail is fluctuating between 4.4V and like 5.2V. I had one more NAOMI power supply left to drop in and that apparently resolved the issue, and it boots past the Memory Check now so I'm guessing the U29 RAM error was related to the power.

fix your voltages and try again, but channelmanic's the guy to talk to about repairing them I think.
 
Is there an adjustment on the power supply for the voltages? I didn't see one. Last week, the ps went up in it, so I grabbed one off the shelf from an air trix we parted out. You're probably right though... Being that the threshholds for the voltages are screwed up on this ps, it probably fried the mobo. I'll have to figure out if it is worth repairing the mobo AND getting a (somewhat expensive) new sega power supply.

Mike
 
yeah, it's one of those dumbass power supplies with the 3 holes, one will have +5, next will be 3.3, next is supposed to be like an indicator light. you have to use a small phillips screwdriver to adjust them.

most people don't even bother replacing those with Sega ones, they'll just use ATX computer power supplies, but you'll have to build an adapter for them. some people make these elaborate guides about scalping motherboard connectors from dead motherboards, not entirely sure why, I found an ATX PSU extension cable that could probably do the same exact thing. you'll just have to gather up the pinout for it, and you'll have to cut your original power supply harnesses to mate the two halves.

I still maintain that with a voltage that high though, you probably have toasted buffers.
 
Ouch.

It's going to be an expensive repair. Right now I'm so backed up on repairs with people waiting that you probably ought to send it off to Ken Westerfield.
 
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