Okay so I went out and bought myself a 25$ (25 canadian lol) atx power supply for my supergun. The guy at the store gave me a funny look when he asked me what I was using it for and I tried to explain. So I take this thing home. And while riding on the streetcar....I notice on the box that it only says it does +5v and +12v. I'm just like ".....wtf.....". I'd seen atx pinouts on google images before showing it having -5v. So I take it home and open it up and sure enough it's missing the wire for -5v. So I checked the specs on it and apparently it's an atx 2.something psu. So I look it up online and it turns out that atx version 1 has -5v and verion 2 or newer doesn't.......f#cknuts.... Since all the stuff I'm running right now only uses +5v and +12v I don't really care. You can just look at the -5v traces on the pcbs from the jamma port and clearly see that they just terminate. So anyway I was just wondering....which arcade pcbs actually use -5v? Is it only williams games? Or do some japanese pcbs use it?
Few pcbs use -5v, you shouldn't worry about it. There were trying to make a list of games that need -5v on ng.com : http://www.neo-geo.com/forums/showthread.php?t=167536 There must be something a little more complete somewhere on the web.
Shogeki, Thanks for that link! nice input from ya! This supergun Canada416 is building sounds like an interesting project.
thanks so much! Yeah I'm not too worried. It wouldn't be very expensive for me to pick up an ATX power supply with -5v on it. I have a feeling that the games that use -5v are mostly williams games which I don't collect.
Mortal Kombat uses -5v. CPS2 uses -5v for QSound/Stereo output. I hear you can get mono without it. Other than those I'm not sure what else does, but it's part of the jamma spec so you might as well have it.
I've used this to get -5V@0.5a which is what you need, works great: http://www.dimensionengineering.com/Negatron.htm
R-type does not need -5v. By "older games" i ment older than 1981... i don't think any game after that used -5v for RAM, but some do use it for the sound as mention earlier in this thread.
Yes, ATX 2.0 and 2.2 don't use -5V. That's one reason why people used to prefer AT PSUs for SGs. And they were easier to turn on! $25 is a lot for a cheap PSU. I would have bought a proper arcade PSU for that, personally! http://web.happcontrols.com/powersupplies/80006400.htm As for which games, you'll find several games that use -5V for sound. Yes, CPS2, I think several Midway games did, and yes Williams. Some (older) games (e.g. Williams) require -12V as well, of course, but your PSU should do that. Umm, why would you spend $20 on that when you could get a PROPER arcade PSU for $20? And you could certainly get an old ATX PSU for less than that!
I used an ATX PSU, shorted the green wire to ground and use the kill switch on the back to turn it on and off as you would an AT. It has -5v too.
wow this +5 to -5v converter looks awesome. *edit* oops it's 20$....yeah that's pointless. Well keep in mind people I'm talking 25$ canadian. And yeah....I just got some atx extension cables off of ebay. The vogatek automatically shorts the on switch so I just use the switch at the back to power on the psu. And I just shorted the on wire on the cheap extension cord so when I disconnect the psu from the vogatek (for using it just for rgb to s-video but not supergun) it still turns on using the switch at the back. But last I checked AT power supplies don't have -5v....they do have a switch that turns it on without you having to connect 2 wires together (2 seconds of soldering fixes that problem on an ATX). And the reason I didn't get a proper arcade power supply is my vogatek uses an ATX port for power. Maybe because I live in the city things are more expensive. *edit* I'm so glad r-type doesn't use -5v that's a sweet game (if you can find the pcb). I was recently watching the bidding on a 1941 counter attack cps1 pcb. It went for 150$.....damn......it's fun but I'm surprised it went for so much.....(and yes I just dropped 900$ on a ketsui so no I'm not just being cheap). I guess that was because of the rarity.....
im drunk so it wont sound right but u can use a regular opamp to generate -5V see the input as an infinite resistor and the output as an infinite source put a resistor (R0) between input (v0) and inverting input (- signed input) and a resistor (R1) from inverting input (- signed input) to output you then have an inverting amplifier wow!!!!!!!!!! but wait a second? what if you use a negative resistor? then you'll have + voltages again omgomgomgomg since we don't really have negative resistors in real life (except using a negative immitance converter) you can worry less about that crap so bottom line: Vout = -(R0/R1) * Vin put V0 = 5V R0 = 1kOhm R1 = 1kOhm do the maths and you'll get to -5V hooray for boobies!!!!
.....boy.....maybe I should have made the title of this thread more obvious. I don't really care how to make +5v into -5v. Honestly another 25$ or so for an ATX 1.0 psu isn't a problem. I was just curious which games actually use -5v. I was surprised to hear that some games use -12v. I don't think I've found -12v on any computer psu pinout chart I've looked up.
I would check your facts more carefully and use a more reliable source, then! At has -5V AND -12V. ATX had both up until 2.0, when -5V was removed. -12V IS STILL THERE. (from http://www.smpspowersupply.com/connectors-pinouts.html) -12V is often blue, -5V was often white. Of course, the ATX form factor was the creation of Intel. You can find the specifications on their site if you're interested. See also: http://en.wikipedia.org/wiki/ATX http://en.wikipedia.org/wiki/AT_form_factor http://www.formfactors.org/developer/specs/ATX12V_PSDG_2_2_public_br2.pdf If you're feeling lazy, just look here: http://pinouts.ru/Power/MotherboardPower_pinout.shtml http://pinouts.ru/Power/atx12v_pinout.shtml
wow that's weird atx does have -12v I never noticed. Guess I didn't care since every jamma pinout chart I saw doesn't show -12v. So which arcade pcbs use -12v?
None, as it's not part of the JAMMA spec, the older you go with arcade boards the more likely it is you will find odd voltages. -5V is used on a lot of pre JAMMA boards for the sound as well as powering RAM and CPUs (the 8080 used -5V). Atari System 1 boards used -15V and +15V for audio. Basically if you want to buy boards that you may require to wire up a loom then you will need -5V more often then not. The -12V could be tapped into a -5V with a 7905 and two external components.
Err, you need to read the question more carefully! He said what ARCADE boards use -12V, not which JAMMA boards use it ;-) Williams boards use -12V and some others - most of them will be very old (70s/early 80s). I can't think offhand of anything other than Williams boards. And yes, there are games that have completely different voltages and can't be (easily) used on a JAMMA rig. Basically, you want a decent PSU that gives -5V, and it should then do -12V by default, too. Then you should be able to play any JAMMA game and some other things (e.g. MVS) with relative ease and a harness.
ahh thanks for clearing this up. Yeah I already have a mvs. I got the mv-1f since it's 100% jamma compatible when you set the sound switch to mono. It also has stereo headphone pins on the pcb. Luckily a 3 and 1/2 inch fd power plug fit the pins. So I just hacked the plug off of an old psu I had sitting around and wired it into a female stereo headphone jack. So I get glorious stereo sound out of it. And the sound on the jamma harness works as well but that's just mono since my supergun runs on standard jamma pinout (except I wired usb ports into the 4th neo geo button pins). It's good to know that all these boards with obscure voltages are older than the stuff I'm interested in. And I'm definitely not a williams fan (sorry mortal kombat).
