What is a jamma harness?

[HOTR6]

Alright I am not to knowledgeable about the whole arcade thing. I have built the cabinet and bought a computer for gaming. Broke the tube on my monitor and was looking around for a way to fix this prob. I found a guy getting rid of 2 cabinets, they both have jamma harnesses and 1 has a monitor. So what is a jamma harness and would it be a good idea for me to get one? Sorry for the lame questions but I am just learning.
Thanks

[Spaz Monkey]

A Jamma harness is the connection from the control panel (joysticks & buttons) to the PCB (printed circut board) of the game.  Or, in computer terms, it's the connection between drives (cd/dvd, hard/floppy) to the motherboard.  It's also determines how may buttons are available.  The default connection is like 3 buttons per person.  You might hear something called a "kick harness".  That allows you to use the kick buttons on Street Fighter type games.  That's a quick overview of JAMMA.  Here a link that can help you out...

http://homearcade.org/BBBB/plus.html

[TravistyOJ]

Man, ive been spending a lot of time over at the neo geo forums trying to get my number of posts up, and i must say that the atmosphere here at BYOAC is much nicer.  There is a very elitist mentality there.
Kudos to you Spaz Monkey for helping out a new person, we all gotta start some time .

[Q*Bert_OP]

JAMMA is the general wiring standard since about 1987, but some games don't use this wiring system...

[HOTR6]

Yes thank you spaz. I am glad I did not get flamed, though I am sure there are peoplewho would like to. So the jamma harness is what you hook to the buttons and joy sticks to. I thought that is what it was. So knowing that......Can you hook that up to a computer OR do you have to have a special arcade? I was looking and thought that I had to buy an Ipac in order to hookup the buttons. Is jamma harness the same thing?

[TravistyOJ]

If you want to keep the JAMMA wiring in tact, you will need a J-PAC (its like a PC to JAMMA converter), i would recommend this if you plan on playing any JAMMA games, if you are putting a computer in there and only a computer, u can rewire everything yourself.   Then u can use a Mini pac or ipac or any keyboard encoder. Just out of curiousity, what are the games/cabinets you would be MAMEing?

[HOTR6]

I bought a computer and then got all the roms for like 400+ games. I need to figure out how it all works. I loaded the ROMS and have an emulator, I can't remember right now. I do remember that the ROMS did not load right and the games did not show up in the emulator. I need to fix the monitor prob in order to work on the rest. I would really like to get this done soon!

Here is what I have done so far.......

I built the cabinet!
I have the computer
I got the ROMS (but there MAY be something wrong with them because they didn't load  properly)
I have the buttons and the joysticks ( have not mounted them in the control box, I was waiting for my husband to design the pannel the way he wanted th buttons set for his hands. He is taking to long so I am going to do it!)
I had the monitor but the tube broke so now I have a chasis (I don't know what kind) and a mounting box

There it is.... Nice maple cabinet with a gaping hole where the monitor goes and a control pannell with nothing on it!!

So I figure I need to get the Ipaq and then wire all the buttons to that and that is plug n play!
I need to figure what I am going to do for a monitor. Will I scavange the tube from a tv I have and get the chasis from 8liners (maybe I should figure out what kind of chasis I have maybe it already is the kind I need)
Then I need to get the computer running and try to figure where I went wrong on the ROMs and emulator
After that MAYBE I will have a working arcade cabinet!!
What do you think?

[RayB]

One step at a time there. I would hook up a PC monitor and get all your software 100% working before you go and switch over to an arcade monitor setup. Otherwise you're lumping all potential problems into one giant heap that you'll have to sort out.

Also, Spaz over-simplified the JAMMA harness explanation. It's not just for buttons. All arcade game machines have a few parts in common:

- Monitor
- controls
- coin switches
- power supply
- speaker

A JAMMA harness is one standard connector that hooks up to the game's circuit board. From that connector are wires that go off to all those things mentioned above (video signals, power voltage, control input, etc).

So what happens is you can take a JAMMA circuit board and swap it with another JAMMA circuit board and then play a whole different game in the machine, usually without doing anything else.

So there you go. Get the emulator software working first (you have ALOT of reading ahead of you, on this site). Next, the simplest thing to do with a cabinet that already has a JAMMA harness is to use a JPAC (not the IPAC) and an ArcadeVGA video card.

~Ray B.

[TravistyOJ]

I'm a little confused, on some posts you ask questions like a newb, but now you are talking about a chasis-tube swap.  I just want to make sure you realzie that monitors can be very dangerous if not handled correctly.  I dont want to sound condescending since im somehwat of a newb, but i didnt want to risk overlooking that. 

BTW, what do you mean by ROMs didnt load properly?

You should post some pics up at the project announcements page so we all can see

[Spaz Monkey]

RayB: thanks, I know I was missing some of the detailed items.

I think another deciding factor is what you will use for a monitor; arcade, pc, or tv?

[HOTR6]

Okay, I am a newb/sophmore! I have read A LOT! I know monitors are dangerous yes. I was going to see if I coould take the tube and chasis to a tv reapir place and have them help me. I dodn't want them to do it for me persay I just want them to "help" me with the whole thing so it is done right.
Now on the note of monitors......I had a monitor (well I still have it but the tube is broke!) I bought it from a guy in Long Beach off Ebay. It worked when I bought it and was totally cool. It hooked right up to the computer and worked properly and EVERYTHING! He even tossed in a switcher so I could hook up the PS2 and game cube and stuff if I wanted. I do not know what kind it is. The tube had a sticker on the back and it is a Philips components. I can't figure where to get a new tube. So I have this tv that is about the same size I was gong to just try to "swap" them but I haven't figured out if the non broken tube will work with the chasis I have. I will probably need to post some pics of the chasis and try to get some help with that. If it wont work my thought was to contact 8liners and get a chasis from them for that tube.
I guess I will try to get an extra computer monitor to hook up to the computer and fix the problems with the games.
After that I will get the Ipaq and stuff.
Here is a question..... why do I need the ArcadeVGA card? Wont the chasis work on the computer like the other one did?
Well that is about it. I will see about putting some pics of it in the projects page.

OH and about the ROMs on a bunch of them, while they were loading it would show some sort of error load failed or something. I can't remember exactly what. I will try to solve that problem in the next day or so so watch out for me to be asking a bunch of lame questions. Once I understand how it all works I can figure things out but I need everything explained to me dummy style!

[pointdablame]

Okay, I am a newb/sophmore! I have read A LOT! I know monitors are dangerous yes. I was going to see if I coould take the tube and chasis to a tv reapir place and have them help me. I dodn't want them to do it for me persay I just want them to "help" me with the whole thing so it is done right.
Now on the note of monitors......I had a monitor (well I still have it but the tube is broke!) I bought it from a guy in Long Beach off Ebay. It worked when I bought it and was totally cool. It hooked right up to the computer and worked properly and EVERYTHING! He even tossed in a switcher so I could hook up the PS2 and game cube and stuff if I wanted. I do not know what kind it is. The tube had a sticker on the back and it is a Philips components. I can't figure where to get a new tube. So I have this tv that is about the same size I was gong to just try to "swap" them but I haven't figured out if the non broken tube will work with the chasis I have. I will probably need to post some pics of the chasis and try to get some help with that. If it wont work my thought was to contact 8liners and get a chasis from them for that tube.
I guess I will try to get an extra computer monitor to hook up to the computer and fix the problems with the games.
After that I will get the Ipaq and stuff.
Here is a question..... why do I need the ArcadeVGA card? Wont the chasis work on the computer like the other one did?
Well that is about it. I will see about putting some pics of it in the projects page.

OH and about the ROMs on a bunch of them, while they were loading it would show some sort of error load failed or something. I can't remember exactly what. I will try to solve that problem in the next day or so so watch out for me to be asking a bunch of lame questions. Once I understand how it all works I can figure things out but I need everything explained to me dummy style!

A few very important notes:

- Unless you know a TV repair guy well, as in he is a good friend of yours, don't expect anyone to "help" you do a swap.  I obviously can't speak for every TV repair guy in the world, but most either do the work, or don't want to be bothered.  Don't expect a walk through, or cheaper prices if you just want "help"

- You say you know monitors are dangerous, but to be blunt... you don't seem like you shoudl be touching one.  It could just be text on the internet, but you don't seem confident and/or knowledgeable enough to do this.  Monitors aren't just dangerous.  They carry enough current to KILL you....  And to swap a tube, you need to play around with the anode, which is the big ol' wire that carries all that juice.  Unless you are 100% certain you know EXACTLY what you are doing... pay someone to do it for you.  Seriously... you don't want to end up dead... its very hard to play your new MAME machine that way.

- I know it's possible to use a TV tube in an arcade monitor, so its a good idea.  I dont' know the specifics as I'm not very good with monitors myself, but it is a possibility.  Worth looking into.

- You don't "need" an ArcadeVGA.  You can hook up your machine without one using an older video card and some hacks.  However, if there is any way you can get one... get it.  It is fool proof and worth every single cent.  It just makes the whole process easier, and it works totally seamlessly with a JPAC.

- on the roms... if you're using MAME, you might be using a set of roms for one version and a mame install of another version.  It's possible that's where your problems are.

Good luck.