So when I test my suspergun out I'm getting graphical glitches, green blocky screen to begin with and the 'Z80 error' text is compressed. My supergun is using a PC PSU for power, it's meant to supply around 30 amps for the 5V lines but the voltage under load keeps dropping to 4.75V. For my setup I had the main ATX connector supplying all of the voltages, with 2 of the 5V lines going to 2 of the jamma connectors each. I connected one of the MOLEX leads to a 5V line and now they're both at 4.9V with the text being less compressed. So now my setup is one 5V line from the ATX connector to two 5V jamma pins and one 5V line from a molex to the other 2 pins, and it's still not supplying enough power. Is there anything else I can do that will help? It seems strange for a new PSU to be struggling with supplying power to this board, I have a 2.5A fuse on the 5V lines so it can't be drawing any more than that. Thank you for your time
This is a neo geo right? Which one? Did you mod it for 5v only? If not, you'll need to supply the 12v. The z80 error means there's something wrong with the audio circuit. It's not necessarily the z80 itself. Has this worked correctly before? Have you tried the board in a working arcade cab? have you tried different carts?
I've heard on ATX PSUs you might need a "shunt" between the 3.3v rail and ground so that the PSU goes into its higher power mode basically. With no load on the 3.3v rail it's not operating at its maximum designated output I believe. But you may want to consult someone with more knowledge of power supplies. I have a Mortal Kombat bootleg board that experiences problems due to voltage dropping well below 5.0 volts. On a PSU that could be manually adjusted I was able to eliminate most of the glitches when the +5v line was brought up, but this later probably was the cause of unintentional damage to another board I had. The ATX regulated PSU is probably a safer bet to use. But again I believe you need to have a load on the 3.3V line. I believe shunt is the name for such a thing that would just draw current and get the PSU operating at higher power meaning more current to the +5v rail so it won't be dropping.
I bought a dedicated Arcade PSU, one of those inexpensive ones with adjustable 5v. I just wired the terminals to a Motherboard molex connector and connected it to my Vogatek supergun. Works awesomely so far, and I certainly do not miss the fan noise. I adjusted the 5V using a big ass resistor first.
I bought the board as faulty in order to have a project and to potentially save some money so the Z80 error isn't the problem at the moment, I'm just trying to get the supergun working so I can do some proper testing. The PSU is supplying the 5V, ground and 12V lines. I'm tempted to get an arcade PSU, but I do want to try getting this one working first since I've already spent money on it. Never heard of this, I was wondering if there is some kind of monitoring ATX PSUs perform to ensure they supply a steady voltage. I'll look into the high power mode thing. Thanks everyone, I appreciate you taking the time to reply
