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Arcade PCB issue

kinooshi823

kinooshi823

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I was testing a jamma harness to possibly build a mini arcade. I hooked all the wires up and then used my UMK3 board to test. The board powers on but when it is on diagnostics, it stops at "at checking scratch rams". I then plugged the board into my supergun and it works fine. What could have caused the issue? is it an arcade power supply issue or?
 
I’d guess power yeah. Check loaded voltage in the cab at the jamma edge and adjust to 5v while powered
 
ekorz said:
I’d guess power yeah. Check loaded voltage in the cab at the jamma edge and adjust to 5v while powered
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this is how it is setup now. I don't know if there is something I did wrong here or the psu isn't good enough. I don't want to fry my board either.
 

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you need a multimeter or voltage monitor to confirm that your power supply is properly calibrated
 
Yes there’s a little knob at the top of the PSU that says “+5V ADJ” and shows a counter clockwise arc. It will increase voltage if you turn it CC. But you need a multimeter set to DC touching pins 1 and 4 on the jamma edge, while the whole system is on. My guess is the 5v power is too low.

Do you have a multimeter?
 
ekorz said:
Yes there’s a little knob at the top of the PSU that says “+5V ADJ” and shows a counter clockwise arc. It will increase voltage if you turn it CC. But you need a multimeter set to DC touching pins 1 and 4 on the jamma edge, while the whole system is on. My guess is the 5v power is too low.

Do you have a multimeter?
Click to expand...
I went and bought a multimeter and calibrated it. I tried 5.00 and 5.01 and the umk3 board stays on scratch ram. I raised the voltage, same thing. 5.18 is the highest I went.

I then lowered it once more and tried an mv1b and it worked. I am stumped here. I then hook the umk3 board to my supergun and it worked fine. I was debating on just buying another arcade power supply. But I don't know if it will solve my problem. I checked the jamma edge too and same reading. I even went and pulled out my mk2 board and the same thing happened as well.
 
5.0 at the jamma edge is the desired spot. Never a need to raise it to 5.18 or whatever.

Anyway that’s kinda bizarre. When you say mk2 did the same thing, do you mean it also fails?
 
ekorz said:
5.0 at the jamma edge is the desired spot. Never a need to raise it to 5.18 or whatever.

Anyway that’s kinda bizarre. When you say mk2 did the same thing, do you mean it also fails?
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Yes. It gets stuck at checking scratch rams. I put on my tekken 1 pcb, and it loaded. mv1b with 161-1 and it worked. 2 out of the 4 MK boards I have tested stops at scratch ram. The other 2 mk boards are still stored but the one I wanted my cab to host (umk3) doesn't boot.

I went and bought a mean well LRS-350-24 for $30 on amazon earlier and another jamma harness. I don't know why this is happening but the multimeter reads correct and I for sure checked over and over the connections. I haven't found no info and nothing I do is fixing this issue.
 
ekorz said:
That’s a good one!
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I bought it from mouser a couple of hours ago.

I received a new jamma harness that I purchased a few days ago early. I wired it and tried my umk3 board and same result.

Even after I had calibrated the power supply.

I hope this one works, as this is so weird. And I would be bummed that I can't make a mini cab because the one game I want to play is being like this.
 
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