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[Repair Log] Sega Naomi

bought another set of naomi2.

by changing the components I now have to confirm the the mainboard is dead.

filter board an net dim work with my new set.

too bad.

Thank you guys for all your help.

And one more question about the voltage... it is now set up that the 5v line gives 5.0 without connection to the naomi2 and 4,85 when It is connected.i took the values at the jamma pins above the power connection at the filter board.

is this ok? or too low?
 
If it runs stable, it's ok.
I would prefer settings like 5.10 V unloaded and 4.95 V under load.
 
hey guys,

i measured the psu in the naomi cab iwill get to use my naomi 2 inside.

the values were way to high.

5,2 v
3,60 v
and 13,6 v

all measured without load

original sun psu.

the 5 Volt line i was able to turn down a but Inder 5 v.

the 3,3 line i was able to turn to 3,45

but the 12v line i was not able to reduce the values.

i am afraid that my new naomi will also be damaged again.

any ideas what i can do?

recap the psu?

thanks
 
Those sun power supplies are a bit like pc atx supplies and need a minimum load.
If you are scared to fry your naomi, you can connect something like a 12V halogene spot to keep it happy.

A beefy resistor can work as well. Load the 5V and 3V3 with at least 300mA

So that's 5V / 0.5 = 10 ohms minimum 3W resistor (5 or 10 W recommended as it will become hot)
And 3V3 / 0.5 = 6.8 ohms minimum 2W resistor.

The 12V usually doesn't has to be very accurate. It's often only used for fan's and audio amplifiers. (No need to load it either)

Normally with such loads, you should be able to adjust 5V and 3V3 properly.

This doesn't mean that recapping is a bad idea.
 
obcd said:
Those sun power supplies are a bit like pc atx supplies and need a minimum load.
If you are scared to fry your naomi, you can connect something like a 12V halogene spot to keep it happy.

A beefy resistor can work as well. Load the 5V and 3V3 with at least 300mA

So that's 5V / 0.5 = 10 ohms minimum 3W resistor (5 or 10 W recommended as it will become hot)
And 3V3 / 0.5 = 6.8 ohms minimum 2W resistor.

The 12V usually doesn't has to be very accurate. It's often only used for fan's and audio amplifiers. (No need to load it either)

Normally with such loads, you should be able to adjust 5V and 3V3 properly.

This doesn't mean that recapping is a bad idea.
Click to expand...
i think the 3,3 and 5 v are ok like this.

if you say that the 12v line will not damage anything then it is ok. i was afraid of this one
 
Dumb question but what is the best way to test this under load? Just put the DMM leads on the ends of the connectors with the game powered up? (Prob sounds bad but I doubt it would cause any issues). I checked my voltages after my recap I did on the SUN PSU in my IDAS3 Single Cab and I think the 3.3 was more like 3.5 at no load and the 5v was like 5.15 (No load). Is that too high? It's been running stable for quite a while so I figure it is fine I just figured it would be worth checking :)
 
If the game is connected, wouldn't that mean the supply is having some load?
5.1V - 5.15V should be fine, but 3.5 is a bit high.
Try to lower it to 3.35. Measure it on the connector that's plugged in the naomi.
Measuring it there means you already compensate the cable losses in the wires going from the supply to the naomi.
 
obcd said:
If the game is connected, wouldn't that mean the supply is having some load?
5.1V - 5.15V should be fine, but 3.5 is a bit high.
Try to lower it to 3.35. Measure it on the connector that's plugged in the naomi.
Measuring it there means you already compensate the cable losses in the wires going from the supply to the naomi.
Click to expand...
This is good advice. Yeah I should have been clearer, the testing I did was when i put the psu back into the game and reconnected it to power then before plugging it into the Naomi I checked voltage at the connectors. I'll measure the psu underload at the connectors on the Naomi. This is a good idea.
 
Anyone know what this problem would be? It works but barely shows anything on screen. Set on 15k mode. Changed bios, removed super cap(wasn’t leaking), changed filter board , fans all work. BasicLly did all the small things ruling the problem to the board.

 
I have two Initial D's side by side, so I was able to swap out components and track down my issue pretty quick. Here's my finding. One game starts up and runs perfectly. The second machine has a black screen and does absolutely nothing, until, I unplug the power to the GD-ROM. As soon as it's unplugged, it fires right up and obviously goes to the error screen. I've taken the GD-ROM apart, and it looks flawless. I'm completely confused. It must be shorting something out. I thought it may be the fan, so I tried running it with the fan unplugged, but that didn't fix it. Any ideas would be greatly appreciated.
 
If you take the gdrom from the working unit and place that in the non working one, does it fix the issue?
This would prove it's an issue with the gdrom.
 
obcd said:
If you take the gdrom from the working unit and place that in the non working one, does it fix the issue?
This would prove it's an issue with the gdrom.
Click to expand...
I'm 100% sure it's the GD-ROM. I swapped both it, and the power supply out just for testing and narrowed it down to the GD-ROM. Literally, the game will do nothing until you unplug the GD-ROM. Once you do, it fires right up. It seems to me like it must be shorting something out.
 
As nem proposed, you could check the voltages on the gdrom power connector. It gets 5V and 12V.
If your naomi dimm is a netdimm, you could consider "compact flash" boot or netboot as alternatives for the gdrom.
 
I'll have to check into it. I don't know enough about it. I'll look up some guides on the compact flash idea.
 
Has anyone come across a Naomi 2 acting like this with a NetDimm? I bought this combo from another user on here, but I keep randomly getting these artifacts and had a hard time getting the NetDimm talking to the Pi upon first hookup. I have a New Net City with Toshiba Tri Tube and the original MP-22160B power supply. Happens randomly at first power up on both 15K or 31K. Sometimes power cycling will clear it, other times it won't.

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