Sega-Naomi

Hi all..



I have what looks like an early version Naomi (metal case rather than snazzy plastic one) running HOTD2 off roms.



Game works fine, all rom/ram tests are OK, everything has been reseated, and the PSU rails are fine.



Problem is, whe the game in attract mode, at approximately the same point (just as 'GARY' is displayed on the screen) the machine locks up. Credits, test button do nothing.



Does anyone have a clue what could be causing this?

Over heating?



I bought my HOTD 2 brand new.. came mint in box. :smt007

If the freezing happens at the exact same spot, odds are it's not an overheating problem. Freezes due to heat are pretty random, even if they are frequent. Are you sure you are not missing any hardware/peripherals that the game might try to look for? :smt017 Check with Andy to make sure.

Hmm, could be the security chip has died.



Naomi rom boards all have security chips, and if they are broken, not working then the game will either not work, or you will get a lock up on the intro sequence, 10 seconds into the game, or when you press start is just some of the effects.



It is normally a 315-xxxx-COM marked chip. COM = world, but sometimes it is 315-xxxx-JAP which means the game is Japan only, I've also seen an -EXP as well.

i bet the game is fooked if the chip died...

There is a square 'Lattice' chip marked 315-6050 on the rom daughterboard.



There is also IC31 on the Naomi marked 315-6188 and IC41 on the Naomi marked 315-6145.



No -COM, -JAP, or -EXP that I can see. (I'm in Australia BTW).



(Game is in a Sega cabinet and was working happily on site before this happened. Unlikely to be missing any bits.. Also, happens straight after initial turn on as well as after long warmup, so unlikely to be overheating.)

If this game is a Naomi mobo in a different package, couldn't you try the game itself in another Naomi to make sure that it is working? :smt102 The rom board should be like a cartridge without the white top and label. :smt045

Could do, but I don't have another Naomi sitting around to try it on.

Thanks for the bios offer via email, but I think we have it & a new bios will prob not slove you problem :smt009

You need to test the rom board on another Naomi, if it still locks up then we can safely say it is the security chip on the rom board.



If it doesn't, then we can safely say its the GPU on the mainboard.