This is at the very bottom of my priority list, but I have an arcade unit that's been awol for the past six months. I was looking to pay someone to take a look, but if someone on this board can point me in the right direction I might be able to fix it myself.
The video is all screwy, blotches of color, flashing every couple of seconds. I don't know if it's the monitor or the video feeding it.
Post by Casethecorvetteman on Feb 21, 2014 23:48:57 GMT -5
Nah its the board not the monitor. Show me a pic of what its doing. It sounds like its doing the startup test sequence over and over, if its a mostly green screen.
Do you have a UniBIOS in there?
First thing, try it with no game cart, if it comes up to crosshatch, clean the cart and cart slot terminals, try it again, if still no go test the voltage on the JAMMA edge, just the 5v connection, 12v is not important and only feeds the audio amplifier. The game will run without 12v present. With a game in and running, you should aim for about 5.1-5.15v at the JAMMA edge, if it drops too low below 5v itll reset due to lack of voltage to the P-ROMs.
Yes, mostly green. It goes black every 2-3 seconds, mostly green.
I think I remember getting the crosshatch pattern when I took out the cartridge (six months ago). I tried a few different carts, none worked, used some compressed air on the slot terminals. What would you recommend to use to clean them with?
Post by Casethecorvetteman on Feb 23, 2014 6:44:05 GMT -5
That is the bootup test screen. The game is not starting.
What does it do with no cart?
Use isopropyl alcohol to clean the cart contacts. Its quite normal on NEO-GEO to have this issue, ive got 2 home consoles and a few MVS boards, about 120 carts, sometimes even new old stock sealed ones need a clean before they will work.
What voltage is on the 5v when it does this?
I think the battery on that board you have is the later version that wasnt an issue for leaking, id have to see a pic of the board cause i cant remember what the 1F looks like. Post a pic of the board with no cart, specifically look around the battery for corrosion.
Calendar error is either a bad Clock/Calendar chip (VERY unlikely), a bad 32.768khz crystal (likely) or no +5v on the chip when powered up (VERY likely). The "no +5v" is caused by corrosion on the board from a leaky battery. Crystal can just be a dead crystal or one killed by a leaking battery. I've also see that message come from gouged traces on the bottom of the board. Calendar Error is also known as "Stuck on Green Screen" when starting. Both signify a calendar problem.
In my case it was a dead battery. I desoldered the old rechargeable battery, desoldered a resistor for the recharging circuit and installed a coin battery holder and battery. Fortunately it wasn't the crystal or the calendar chip. Total time of repair: about 15 minutes.