Supergun power wiring questions

E

ericb

NEST Puppet
Joined
Nov 1, 2004
Posts
177
I'm finally getting around to building a Gun and I got a quick couple of questions.

First off, just to give you an idea, I'm using a PC power supply... AT as it should be.

1. When soldering up connections, I've got a 2 amp fuse on a +5 line and a 10 amp fuse on a +12 line. Would I be able to connect every +5 jamma connection to this one +5 line, or would I need more than one? Same question about the +12. I can't see any reason why I wouldn't be able to split off all the necessary connections from the one +5, but I just want to be absolutely sure about that.

2. I need the gun to be CPS2 compatable (along with other PCBs), so I'm wiring up a -5v line as well. I read somewhere (forgot where) that it was OK to leave this wired up (without a switch) when hooking it up to an MVS board, because there simply is no contact on the MVS board for where the -5 line goes... is this true? I don't want to wire this up without a switch and then realize after I get an MVS board that it was the wrong thing to do, and have to add one afterwards.

As always, thanks in advance... the community really pulls through for each other on this board, and it's good to see.
 
A

Amano Jacu

Charles Barkley
Joined
Sep 11, 2001
Posts
8,594
I'm no expert in 1), but in 2), yes, connecting -5V is perfectly OK for all boards even if they don't need it. Notice that CPS2 doesn't need -5V anyway.
 
Yodd

Yodd

Iori's Flame
20 Year Member
Joined
Feb 7, 2002
Posts
8,214
ericb said:
I'm finally getting around to building a Gun and I got a quick couple of questions.

First off, just to give you an idea, I'm using a PC power supply... AT as it should be.

1. When soldering up connections, I've got a 2 amp fuse on a +5 line and a 10 amp fuse on a +12 line. Would I be able to connect every +5 jamma connection to this one +5 line, or would I need more than one? Same question about the +12. I can't see any reason why I wouldn't be able to split off all the necessary connections from the one +5, but I just want to be absolutely sure about that.

2. I need the gun to be CPS2 compatable (along with other PCBs), so I'm wiring up a -5v line as well. I read somewhere (forgot where) that it was OK to leave this wired up (without a switch) when hooking it up to an MVS board, because there simply is no contact on the MVS board for where the -5 line goes... is this true? I don't want to wire this up without a switch and then realize after I get an MVS board that it was the wrong thing to do, and have to add one afterwards.

As always, thanks in advance... the community really pulls through for each other on this board, and it's good to see.
Click to expand...

1. Unless I misunderstand what you are saying, you are going to want to reverse those fuses. A 2 amp fuse on the +5 volt is gonna blow probably as soon as you power the first PCB up. And 10 amp on the +12 is totally overkill. Probably want something closer to a 2 amp on it. This is of course if you use them at all.

2. CPS2 does NOT require the -5 volt rail. Its true that there is nothing present where the -5 volt would be on a MVS pcb.

If you are using an AT style supply, why not just use the switch thats built into it or the external one that usually is supplied with it?
 
norton9478

norton9478

So Many Posts
No Time
For Games.
20 Year Member
Joined
Oct 30, 2003
Posts
34,074
Ok, Ok,

So many issues.

2 Amps seems a little low on the +5v line.... I would go with a minimum of 6 amps. 10 amps on the +12 seems to be unessacary. Can your PSU even output 10 amps on that line. 2 amps should be enough.

Wire up the -5. You might need it for a handfull of games. You don't need a switch. If a jamma board doesn't require -5v, then the -5v line just wont go to anything.



ericb said:
I'm finally getting around to building a Gun and I got a quick couple of questions.

First off, just to give you an idea, I'm using a PC power supply... AT as it should be.

1. When soldering up connections, I've got a 2 amp fuse on a +5 line and a 10 amp fuse on a +12 line. Would I be able to connect every +5 jamma connection to this one +5 line, or would I need more than one? Same question about the +12. I can't see any reason why I wouldn't be able to split off all the necessary connections from the one +5, but I just want to be absolutely sure about that.

2. I need the gun to be CPS2 compatable (along with other PCBs), so I'm wiring up a -5v line as well. I read somewhere (forgot where) that it was OK to leave this wired up (without a switch) when hooking it up to an MVS board, because there simply is no contact on the MVS board for where the -5 line goes... is this true? I don't want to wire this up without a switch and then realize after I get an MVS board that it was the wrong thing to do, and have to add one afterwards.

As always, thanks in advance... the community really pulls through for each other on this board, and it's good to see.
Click to expand...
 
E

ericb

NEST Puppet
Joined
Nov 1, 2004
Posts
177
Goddamn, I'm embarassed. Yeah, I just re-read my first post and realized that I mixed the two up... I would be putting a 10 amp on the +5 line and a 2 amp on the +12 line.... I really gotta get more sleep.

The answer to #2 was perfect, so thanks guys. I was under the impression that the CPS2 used the -5v line (never trust any board aside from this one...), so I had some concern for it, but I might as well hook it up anyways.

Again, for the first question... just want to make sure that it's OK to hook up all the power connectors from the jamma to that one fuse holder for each +5 and +12 from the PSU...

Thanks again, guys.
 
R

RiotoftheBlood

Chin's Drinking Partner
Joined
Jan 10, 2001
Posts
2,779
ericb said:
Again, for the first question... just want to make sure that it's OK to hook up all the power connectors from the jamma to that one fuse holder for each +5 and +12 from the PSU...

Thanks again, guys.
Click to expand...

Yes, it's OK... however, for the main power line from the power supply to the fuse, use wire that will be able to handle that much current safely.

Here's a reference:

http://www.powerstream.com/Wire_Size.htm

From my experience a CPS-II supergun will draw roughly 4 A from +5 VDC and roughly 0.5 A from +12 VDC. For my main power lines to the fuses I used 16 AWG and 22 AWG, respectively. However, since it appears you're striving for general JAMMA compatibility you may want to conisder using even thicker wire. Using thicker wire is always electrically better (although thicker wire is more unwieldly).

Also keep in mind that your ground wires must also be able to handle the total current going out (the sum of the +5 VDC, +12 VDC, and -5 VDC currents). That's is based on Kirchoff's Current Law; current in = current out.

You may want to do a little studying on electrical basics before you begin. At the very least you should know Ohm's Law and Kirchoff's Current Law, and you should also know electrical safety especially considering you're using an AT power supply, which is quite powerful.

Good luck with your project! :glee:
 
You must log in or register to reply here.
Top