MK 2 help

smitymike11

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My son wanted to show his friends the games today. Everything powered up expect the MK2. The marque lit up but I did not see anything else no sound even. I switched the game off and the screen flickered and turned off. I am going to take a look tomorrow and see what I can see. What should I look for? Does this sound like a board issue? When I bought this game it worked fine. I did notice I had it to close to the garage door and when it rained it was getting a little damp. Since then I have moved it away from the door and have had it working. The plan tomorrow is to take off the back and see if the leds on the board light up. Is there anything to look for?
 
Do you have a voltmeter by chance? How about the sound, any hint or buzzing? Does the tube on the bottom of the rear side of the monitor glow? Im no expert but these are clues to start somewhere.
 
I do have a voltmeter. No sound at all, at least from what I could hear. Not sure about the tube yet, I'll have to pull the back off and see.
 
most likely you're looking at a failing power supply. the grey Peter Chou units frequently do this where it's like the game doesn't get power. it goes into a shutdown mode due to any number of reasons that simply put translate to "it's time for a new power supply"

though I have had luck resurrecting power supplies that did that.

I would rule out the monitor if you saw anything on the screen. you can rule out the line fuse too, since the marquee lit and the monitor is apparently working.
 
mine does the exact same thing. I noticed that when I unplug and replug the jamma harness this normally gets it to work. I was told mine is a bad power supply as well. I havent gotten around to fixing it yet as I have other projects and it works 9 outta 10 times when I power it on.
 
I hope it is just the power supply. Where do I get a replacement? What ones will work? I would rather buy one that is a direct plug in with nothing to mod.
 
commonly the problem is from oxidation or whatever forming on the +5V adjustment pot. easiest way to attempt to fix that is to "wipe" the +5V adjustment pot, which effectively means you turn it back and forth between its extremities a few times and in most instances it can "clean" itself. the only problem with that is you won't know where the voltage setting is at when you're done.

it's frowned upon to power a switching mode power supply on with no load (meaning you unplug the JAMMA harness) because it can damage the unit. you can however get away with running it without a load for a few seconds, so you would have to be rapid fire in adjusting it back to about 5.2V and powering it back off again -- easiest thing you can do is use alligator clips running from your meter to the power supply lugs (red probe goes to the +5V lug, black probe to the GND/COM lug) so your hands will be free.

I concocted a tool that puts a load on the power supply so I can do that kind of test without risking toasting one of my games. :D

I suppose you could do the same by pulling one of your working coin door lamp fixtures (the bulb must be good) and attaching alligator clips to the terminals and hooking one to the +5 lug and the other to the GND/COM lug on your power supply, then you can meter where you're at.

if none of this makes sense, please tell me. lol. I think today might be a good day to do a new pictorial guide...
 
I think today might be a good day to do a new pictorial guide...

Just do it.

Doo%20it.gif
 
Power supply Voltage isn't really something that can be preset, the main reason being that different JAMMA harnesses have different resistances in the wiring.
 
IMO use a cheap "Test" board for initial power up and make adjustments off that, then power up your MK2 (unless you don't care about it). now i'm not saying that it wouldn't be ok new out of the box but your safest bet is to power up with a cheap board first and adjust accordingly.
 
every power supply I've bought new came preset to exactly 5.00V. it's a safe starting point, it won't damage anything. I still don't know if you're running a dedicated cab or what, but I know the dedicated MK2's come with a massive jungle of wiring, so you'll probably wind up setting the power supply at 5.2V and it should be fine.

make note of my hundreds of other posts about cleaning your JAMMA edge. then you won't have to run your power supply so high, or risk damage down the road.
 
every power supply I've bought new came preset to exactly 5.00V. it's a safe starting point, it won't damage anything. I still don't know if you're running a dedicated cab or what, but I know the dedicated MK2's come with a massive jungle of wiring, so you'll probably wind up setting the power supply at 5.2V and it should be fine.

make note of my hundreds of other posts about cleaning your JAMMA edge. then you won't have to run your power supply so high, or risk damage down the road.

It is a dedicated MK2. I don't have a lot of time right now to mess with it, I do not live in the house since it is gutted, so I was thinking try replacing the power supply and go from there. If I buy a new power supply and hook it up right out of the box and the voltage is at 5v will everything work or will I need to turn it up? Can I not just hook up my meter to the power supply and turn it in for a sec to check the volts with nothing else hooked up?
 
Can I not just hook up my meter to the power supply and turn it in for a sec to check the volts with nothing else hooked up?
Absolutely, be quick though. Then once you've connected your board, measure again (at the board, NOT at the power supply) and increase the voltage to an acceptable level if necessary.
 
Absolutely, be quick though. Then once you've connected your board, measure again (at the board, NOT at the power supply) and increase the voltage to an acceptable level if necessary.

Good, I don't have any spare boards to test with. I think for $20 I'll start with the power supply and hope that is all it is.
 
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