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GravitySandwich

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Hello Everyone!

I just recently got into Arcade's and bought two defective Sega Naomi boards. I get it, now you're wondering, WHY did you buy defective ones? Well that is a good question, I'm a console collector that only collects defective consoles and fixes them. So far i have over 25 consoles in my collection that are all back in fully working order, and i would love to continue that with the Arcades to preserve these wonderful machines. But now back to the Naomi's:

One of them is now succesfully booting but i still have some issues to solve. The board is currently starting up with a green screen, slowly transitioning to the Naomi Logo and flickering like crazy(Error 01 can be ignored, booted it without a game). The boards came in pretty rusty but that's all cleaned up and all solder points are in good shape. No damaged traces or corrosion. Anyone had this exact issue and can tell me what fixed it for them? Or do you guys have any clue where to look for? Test and Service are both not responding when clicked on the board. It once tried to boot Test mode but kept rebooting.

Video:

The second one is just completely black on boot. No video or audio at all. I currently ordered some KR-5R5H104-R caps to replace the old EECS0HD104H capacitor. That one seemed to have leaked but did not damage any traces yet. This machine was also rusty but that's all cleaned up now. I did find a thread about troubleshooting the naomi black screen (This one). I tried the following of that:

-Bios Corrupt or not present (Can't test this yet. I don't have the proper tool to extract the bios chip from the board)
-Fixed CPU had more particularly to the BGA (rare as on the N1) (I don't really get what they are trying to tell me with this one)
-supercap (a change or which sank) (Ordered, will come in in a few days)
-GPU Fan not working (GPU fan spins like a champ)

Many thanks already!
 
Last edited:
Following in hopes someone has solutions for the black screen and no sound. I have a n1 with the exact same problem.
 
Managed to get a little further then before. Replaced the JVS board and now my test and service buttons work. Test mode is very unstable though and crashed 99% of the time. I did manage to do the RAM test once and got this far. Looks like i need to change some chips!
f57422d50e3095b95425f5c3bd887cac.jpg
 
It's actually a good idea to start arcade repairs with the Naomi coming from the console world:
- it has a case protecting hardware
- it has a test mode
- it's well known hardware

Consoles are generally a lot easier to repair than arcade gear, they sold millions, are well known technically and have a case to protect hardware.
On the other side arcade PCBs:
- are just bare boards most of them time with no protection from scratches, spillage, shocks
- are plugged to manually adjusted PSUs and can be damaged easily if voltages are cranked up too much
- most of the time poorly documented if at all
 
It's actually a good idea to start arcade repairs with the Naomi coming from the console world:
- it has a case protecting hardware
- it has a test mode
- it's well known hardware

Consoles are generally a lot easier to repair than arcade gear, they sold millions, are well known technically and have a case to protect hardware.
On the other side arcade PCBs:
- are just bare boards most of them time with no protection from scratches, spillage, shocks
- are plugged to manually adjusted PSUs and can be damaged easily if voltages are cranked up too much
- most of the time poorly documented if at all
Yeah i found out about the spillage one... The one that is not booting has a lot of it... I'm going to clean it up in the ultrasonic first and see if it works after that. Otherwise the troubleshooting fun is going to start...

56018057a665d42974cea028c9922162.jpg
90749237e157fea5879329d7e966f990.jpg
 
Update on the booting one with bad memory chips. IC09 had a leg that wasn't connected properly anymore. Soldered it back on and IC09 is fixed. IC16 needs replacing but the chips are very hard to find. I'm going to try a newer Samsung alternative with simular specs and see if that works.
 
New memory just came in! Going to solder it on in a few days and see if she's alive again!
 
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