Can a JAMMA Harness go bad?

spmahn

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So I turned on my machine, a 4 player Konami cabinet, tonight and it booted up no problem. Then I turn it off and switch out the board, no problem, then I turn it back on and I get nothing. Monitor appears to turn on fine, speakers sound like they're on, marquee lights up, power brick is on, but the board doesn't seem to boot, and for some odd reason no coin door lights. I tried swapping boards, and I'm getting the same thing no matter what. I will be back tomorrow with more specific details, but just based on these symptoms, does this sound like a bad JAMMA Harness? Are they easily replaced?
 
I would check the Jamma connector carefully -- everything look good in it? If you probe it with a DMM do you get the correct voltages at the correct places?
 
It's rare for the harness itself to fail - especially since it was just working. That said, I've seen plenty of faulty harnesses - usually the connector just gets worn and corroded, and the wires start to break off. It's rare for one to fail such that nothing happens - usually things just get intermittent, or you'll have a switch or a color not working.

Based on your description - I'd say the power supply died. That's a lot more likely. Especially since your coin door lights went out. If this cabinet has it's coin door lights powered off the switcher (common only in newer games), then there's your answer.

Check for 5v at the board, I'm willing to guess you're not getting anything.

-Ian
 
I'll check the connector a bit more carefully tomorrow. A multimeter right now would probably be a bit beyond my technical skills, but I'll keep that in mind as a possibility too. Thanks.
 
It's rare for the harness itself to fail - especially since it was just working. That said, I've seen plenty of faulty harnesses - usually the connector just gets worn and corroded, and the wires start to break off. It's rare for one to fail such that nothing happens - usually things just get intermittent, or you'll have a switch or a color not working.

Based on your description - I'd say the power supply died. That's a lot more likely. Especially since your coin door lights went out. If this cabinet has it's coin door lights powered off the switcher (common only in newer games), then there's your answer.

Check for 5v at the board, I'm willing to guess you're not getting anything.

-Ian

Looks like replacement power supplies are pretty cheap, is replacing one an easy switch, just replacing the wires? I have no electrical skills whatsoever, but I'm learning. Thanks.
 
Looks like replacement power supplies are pretty cheap, is replacing one an easy switch, just replacing the wires? I have no electrical skills whatsoever, but I'm learning. Thanks.

Replacing a power supply is really easy. But before you buy parts, you should verify that the power supply is your problem. You really should own a multimeter - if you don't have one, buy one. Even a cheapie $5 meter from Harbor Freight is good enough for basic stuff. I recommend a digital meter for people getting started. That way you don't have to think to read it :)

Set the dial to DC volts - on a non auto-ranging meter, select the 20v scale. Look at the power supply - there are screw terminals on the back of it. Find the one labeled COM and the one labeled 5V. Turn on the game (with a board connected, you need load for a power supply to regulate). Put the black lead from your meter on the COM terminal, and the red lead on the 5V terminal. You should be getting around five volts, give or take a tenth of a volt. Now move the red lead over to the 12V terminal. You should be getting twelve volts, give or take a tenth of a volt.

If either of these give you no reading, or a very low reading, then you have a power supply problem. Assuming of course that your board is good - a shorted board can shut down the supply.

Actually changing the supply is really easy, just loosen the screws holding the wires in and slide them out, and move them over to the same marked terminal on the new supply. Do one terminal at a time if you're unsure, that way you don't get the wires mixed up.

-Ian
 
Just yesterday I had a problem where a wire broke internally. Insulation was intact, but a quick continuity check between the connector and the endpoint quickly found the offending wire. I then stripped small areas (starting halfway) until i found the break. Cut all the way thru there, put heat shrink over my prior strips, and soldered/heat-shrank the break back together....
 
And be aware (if it comes to that) that there are different styles of power supplies. If you're doing it for the first time you'd make your life easier if you bought the same style as what you've got in there now.
 
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