Changing Jamma Harness Question

Optimus Prime · 10-07-2012 02:26PM #1

Possible stupid question here..

I bought a new Jamma harness and want to stick it into a cab i have here. currently the crt in it displays no picture.

Can i change the Jamma harness in the cab without discharging the monitor??

I just dont want to electrocute myself, if the cab is switched off am i ok to change this?

LoGiE · 10-07-2012 08:50PM

Howdy!,

It's all just molex connectors for the monitor so no. The Jamma harness will connect to the video output of the monitor and speakers and you will need to wire it up for power, player buttons and coin door /credit button.

Take a look here for information on which wires go where.

Optimus Prime · 10-07-2012 08:55PM

so i cant change it without discharging?

LoGiE · 10-07-2012 09:17PM

You don't have to. Repairs that involve removing the chassis from the tube you discharge the montor.

If you want complete peace of mind just discharge it otherwise just plug it out and disconnect the molex connectors connected to the jamma harness and avoid touching the flyback obviously!

http://www.arcaderepairtips.com has some good info and videos you should check out.

Optimus Prime · 10-07-2012 09:28PM

ah cheers, ill give that a read thanks a lot! if you dont hear from me again... things went wrong. haha..

LoGiE · 10-07-2012 10:14PM

keithgeo wrote: »

ah cheers, ill give that a read thanks a lot! if you dont hear from me again... things went wrong. haha..

I've been shocked before, two hours after the cabinet had been powered down. I lived to tell the tale and was more concerned I'd broken the machine!

You'll be fine once you've invested in some rubber 'croc' shoes and don't have a pacemaker.

CathalDublin · 10-07-2012 10:27PM

Yes its fine, your only plugging a molex r,g,b,gr,sync into the chassis, noting live.
its perfectly safe, just don't go pulling the anode cap off the tube

and if your marque light bulb needs a test, give this a try.

https://www.youtube.com/watch?v=Rb6vMgurAH0

Optimus Prime · 11-07-2012 11:41AM

haha i think ill pass on doing that, that lads crazy!

Optimus Prime · 11-07-2012 10:13PM

So I removed the old Jamma harness from the cab i bought a couple of weeks ago. I bought a new one off ebay to replace it. The power and Video on the old Jamma harness was connected via molex connecters.

Video connected to a cable hanging from the back of the monitor

Power connected into the power supply.

My new Jamma harness is just wire for video and power.

How do i connect these in? How can i connect the power to powersupply with no connecter on it? Do i have to add one myself?

Here is an image of the new power wires and the old with the connecter on the end... Help!

CathalDublin · 12-07-2012 09:25AM

You can either buy pins for that molex connector in radionics or don't use it,
For the 5going into the back of the monitor either get new pins or cut and join the wires, I'd the heat shrink each wire

Optimus Prime · 12-07-2012 09:38AM

So i need to get 2 molex connecters (or use the old ones), one for video and one for the power?

Also do the wires have to go into the right sections in the molex connecter or can i put them anywhere? im guessing i have to find out what each one is from the jamma harness and put it in a certain hole in the molex connecter?

is there a special tool i need for putting these wires in?

Ive never done this before. thanks!

CathalDublin · 12-07-2012 05:36PM

keithgeo wrote: »

So i need to get 2 molex connecters (or use the old ones), one for video and one for the power?

Also do the wires have to go into the right sections in the molex connecter or can i put them anywhere? im guessing i have to find out what each one is from the jamma harness and put it in a certain hole in the molex connecter?

is there a special tool i need for putting these wires in?

Ive never done this before. thanks!

I think there is a special tool but its handy enough to just push them in by hand or the more stubborn ones with a small flat head screwdriver, its taking the old ones out that's difficult.
When I changed my harness I just wired everything directly without using molex connectors, I got a new molex plug for the monitor alright. But
I ran all my wires directly to the control panel/speaker.
If I ever want to put the molex connector back in I can just cut the loom and pop it in:eek:

Bob roberts has an excellent guide here

Optimus Prime · 12-07-2012 06:26PM

Its just so confusing, normally id have no problem installing this. the power supply has a connecter on it so it looks like i need to add a connecter onto the jamma harness. i dont think i can just wire it up. photo below.

The one on the right is the old jamma harness plugged into the power supply. so i need to take that, find out which wires are in which holes on that molex, and put the correct wires from the new jamma harness into the same holes?

CathalDublin · 12-07-2012 06:31PM

Ah, I see I've never seen a PSU like that before. That looks like it was originally specific to a game.
All my cabs have had something similar to this in them, best look up the manual for that PSU or dust off the multimeter and draw up a pinout diagram

Optimus Prime · 12-07-2012 06:33PM

yeh there is one of them in the other cab i have, they seem straight forward, unfortunatly this one is different..

LoGiE · 12-07-2012 07:30PM

Mitchmagic will have arcade power supplies which will make it a lot easier.

Changing Jamma Harness Question

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