The board powers on, but i only get some glitches. The board has been modded for 5v only. There are no visible broken traces. Any ideas?
does a game boot and play with glitches or its just glitches?. I had problem with glitches before and was dirt in the slot and a game. Can you be more specific and if you can put a photo of the problem. Also does it glitch when you turn it on without a game?.
That was fast. Thank you. The game doesn't start. It has glitches with or without a game inserted. The glitches are kind of flashing and are looking like little squares with letters/symbols inside. I will post a photo.
This is how it look. I've tested the bios in another board and it's ok. I've checked a0-15 and d0-d15 between bios, 68hc000 and ram1 and ram2 and are ok. I've replaced the work ram. Same problem.
If you check the bios and the ram is working fine then you should check with Xian Xi he will surely tell you what might be the problem.
Does it flashes the screen in a fixed interval ? NEO-GEO has a watchdog which tries to reset the board once per second if the program isn't running. No screen flashing would hint at /RESET line being stuck low... That certainly look like the BIOS is bad or there's something stuck on the 68000 BUS.
The screen is flashing very fast. If i remove the bios the screen flashes too, but the colors are different. The bios has been tested on another board.
Something is preventing the 68000 from running the BIOS code. Judging by the fact that connecting the bios changes what is on the screen it's probably running a bit then failing. I would have all data and address lines traced from the CPU chip to the BIOS ROM and check if any is broken. Probably an address line is cut by a corroded trace which isn't visible.
Different NeoGeo MVS boards take different voltages, check it isn't one that needs -5v or 12v or whatever as well as 5v; and also the amperage it takes on your 5v line, again, different boards are different; your board seems to need 3 amps on 5v, is your regulator outputting more than that for continuous use (not peak?). This might help : http://www.hardmvs.com/html/MV-1A.htm
bacteria is right the power needs to be at least 3 amps if its lower it might not work properly. But check the traces too.
I didn't consider the power supply. From that link: [FONT=Arial, Helvetica, sans-serif]"The only differences between the MV-1A and the MV-1FZ are the amperages, The MV-1A takes +5V 3A, and the MV-1FZ takes +5V 7A and the socketed BIOS is closer to the Jamma connector on the MV-1A[/FONT]" I also have a FZ running fine on psp power supply so i assumed that will work in a MV1A. MV1A has this mod: http://www.jamma-nation-x.com/jammax/tutorials.html?show=mv1Ax5v I did a little experiment. In FZ i removed the work ram and the screen it's similar, but it's not flashing. to l_oliveira: i've allready checked all data and address lines traced from the CPU chip to the BIOS
