Looking for a little help from someone who knows arcade machines.

I've got a dedicated MK4 cabinet. I've had it for 3-4 years and it's worked pretty well. In the past year or so, I would power the game on and the game wouldn't power up. The marquee would light up but that's it. I noticed the power supply wouldn't power on (no fan). So I would mess with the potentiometer on the side of it and eventually get the game to power up.

It would be fine for a month or so and then I'd have to do the same thing. I'd mess with the potentiometer a little and then it would work fine.

Well last month I couldn't get the game to fire up no matter how much I fiddled with it. The power supply would kick on, but no game. Some of the LEDs on the MK4 game board would light up too.
So I swapped in a multicade jamma board and that worked fine for a few weeks. Well now neither of them work. Do I have a fried power supply? Did my power supply fry both my boards? Did my monitor take shit? What should I test? I have a DVOM and am handy with it. I just need to know what to test.

Thanks in advance for any help!!!

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Thanks for the responses guys. Yeah I figured I shouldn't adjust the power supply voltage blindly. Thought it might bite me in the ass eventually, lol!

I cannot start a game or hear any sound, so I don't think it's the monitor. Seems like the game just isn't firing up. Board or power supply issue.

Where would I check this? On the PCB connector that plugs into the board? Or at the 9-pin connector coming off of the power supply directly?

If the board is fried, any idea who I could send it to for repairs?

Also, where could I find a power supply replacement? I've searched online and haven't come up with anything based off the part number.

I ordered the power supply. Found it on Amazon. Cost a little bit more but it's all good. I'll get that installed and dial in the voltage. I'll report back and go from there. Thank you all!

So I got the news power supply installed. Dialed in the voltage to 5.05-5.1 volts. Still no luck with either the Mk4 board or the multicade board. The screen comes on, but no fake starts up. I think I smoked these boards.

I may take the board out of my cocktail arcade and try that. Just don’t want to smoke that too.

Here is what the MK board looks like.

Any other thoughts?

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I think I’ve got it figured out. I smoked both the MK4 board and the 512-1 Hanna board when I cranked up the 5V blindly.

I plugged the 512 into my working cocktail arcade. Didn’t work. Plugged the cocktail arcade 60-1 into the MK4 cab and it worked. Of course the screen was all screwy and sideways, but I expected that.

So where is the best place to buy a 512-1?

Also where is the best place to send in the MK4 board for repairs?

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