Well, my junk Neo Geo saga continues. First the PSU was sorted and yesterday the 100 yen joystick arrived and today I found out that even though the Mega Drive RGB cable doesn't fit the Neo Geo, the Mega Drive composite cable does and I had one of those lying around. So on booting up every game I have for the Neo Geo I get the below garbled screen with no audio or anything. This is before the Neo Geo splash screen should come on. If the game comes on it's glitched as below. BUT, if I go in to the Neo Geo memory card screen then exit that, the game will boot fine. however all is still not well. While the games are now fully playable there are some small graphical glitches on any sprite that is manipulated such as rotation, scaling or distortion. Sprites that don't have any manipulation seem to be fine. What could be causing this problem? Is it the BIOS or could it be an actual issue with the Neo Geo's CPU?
broken or damaged trace perhaps? You could try with a Unibios as this does skip over some errors when loading but i dont think that will help you much I have been playing with a few Neo Geo boards recently and i have seen a similar green pixelated screen on a few of them and all those times it turned out to be a problem with the power supply, now your saying you had problems with your power supply but they are now sorted, are you 100% sure its fixed? do you have another one to test with or could you borrow one from someone to try out? just my 2p
I'm afraid I can't get an official PSU. They're so hard to get hold off so I'm stuck with the one I'm currently using. I'm not sure if it is the PSU though. Take a look at Samura Spirits. When the screen is zoomed in the image is OK But when the screen zooms out it looks like crap. A PSU wouldn't have this sort of effect, would it? I'm not sure.
I'm glad that what i tell you about the megadrive cable helped you. Do you clean the cart slot, many lines that come and go, sometimes is a dirty slot, but other times is traces that do not have continuity. You will have to open it up and check. Also use this to check is something is wrong, this is when you turn it on without a cart inserted. Screen color meanings Blue: All tests passed (The AES does not test the Z80 sound IC). Red: Work RAM error ($100000 region). Green: Palette RAM error ($400000 region). Yellow: Video RAM error (programmed through custom port). Pink: BIOS checksum error (0xC00000 region). Cyan: Memory card error (only tested if card in unit and blank).
The first photo indicates that something was something on the 68000 bus wasn't making connection so it crashed. When the games start (and run without crashing) the connection is fine. The RNK2 distortion looks like damage to a custom chip, but since it's gone in the other pics that's not it. The SS distortion is caused by a bad connection to the ZMC2 chip inside the cart, or because the ZMC2 isn't functioning correctly. My guess is that your power supply is insufficient which is leading the chips to act up. (+ connector needs cleaning). When the power supply doesn't have enough current capacity the voltage drops, when the voltage drops chips slow down and cause glitches.
Thanks for the info, Calpis. I've just switched the AES on without any cart in the machine to see what colour screen I get and mine was white with little black dots crawling up the screen. But after 3 minutes it turned blue. So all the chips seem to be fine on the console. So I'm guessing it is a PSU problem as you and Mystical mentioned. Also thanks to Kaicer for the Neo Geo screen colour guide. I'm so happy mine turned blue. I'm pretty sure the power issue isn't due to dirty connections as the cart slot and all games were cleaned with quality cleaner and the PSU port looks brand new as does the inside of the console. All caps are fine too. So the PSU I bought mustn't be very good despite having the correct voltage and amp rating. I just bought a Pro-Pow spec PSU for the Neo Geo from http://retrogamecave.com/ It's not an official product but is made just for the Neo Geo. Fingers crossed this thing will work. It is designed for the US market I guess but since Japan and the US use the same power system that's not a problem.
The BIOS can only test memory chips, it's completely oblivious to any other board/chip damage. A blue screen is a good sign, but it's not a true clean bill of health. Since apart from the glitches (which aren't consistent with board or chip damage) everything looks OK, a power issue seems most likely. Another possibility is that you could have a 9V system in a 5V case (some 5V systems were upgraded with a switching regulator board by SNK, but it would be pretty apparent). In that case using a 5V supply wouldn't maintain correct 5V regulation.
Ah, yes. I've read about the 9v boards in older cases. Mine isn't one of those thankfully. I went for the older model due to the cleaner RGB signal they give or so Neo Geo fans would have you believe.
Yea but Neo Geo power is external, not internal like 32 bit systems and above. But considering how recent those adapters are maybe it will be fine.
Japan is actually 100v to 110v. The PSU I bought is 100v compatable. Other good news is that my RGB cable arrived today I'm going to wait for the new PS2 before using it though.
