My neo geo aes sometimes turns on and sometimes not

Any ideas why? Sometimes the switch turns it on and sometimes it does not... Thanks! (That's how it was since I bought it, 6 months ago).

Maybe the power supply has issues, maybe the switch is defective, the power jack on the neo geo might be loose. There are many possible causes for this.

Regards.

Got a multimeter? If so, I'd start by taking the top off and measuring voltages, especially when the system doesn't turn on.

Well, thank you all for your suggestions but I don't have a multimeter and my electronics knowledge is non-existent. One thing is for sure: the label of the neo says use 5V (plain pro-pow) ac adapter and the guy I bought it from sold it to me with a genesis 9V one. When I asked him why he said that he used a 5V one and it wasn't working, so he was always using the 9V genesis one... That's what I am using for 6 months now. The serial of the console is on the 40000+ range (NTSC) if that helps. Also the neo came with a scart cable which had a jack cable attached to it too and only when I plugged the jack cable on the earphones I managed to listen to the sound from my TV. Just some more information for someone who knows better than I do. Any ideas now?

The switch is defective. It's also hard to find a direct replacement. You might be able to clean it with some contact cleaner or something.

Thanks man, that's a relief despite the fact that the direct switch replacement is hard to find as you say. I was suspecting the worst all this time but the fact that the neo is still alive and playing confused me and thats why I asked after so long.

You can't always go by the label these days after all these years, someone probably did a case swap with a defective unit. If a Genesis supply was used on a 5v system you'd just get some magic smoke.

That's good to know. Contact cleaning does not sound like a big deal even to me anyway. If the situation gets worse I am gonna open it, clean it and then see how it goes.