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mathewbeall

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Hi Folks,

Just picked up a UMK3 board off of ebay, and after hooking up the -5v rail - the sound is good (that was my first issue).

The next issue is a bit weird - I have to apply some pressure to the jamma connector for the board to stay in operation (or boot up). My Jamma connector isn't loose (as it works on every other board I have) and I even tried prying the pins out a bit to see if just maybe it was a connection issue, but that didn't help.

Any ideas on what to check?

Matt
 
I would guess some kind of cold solder joint if the JAMMA connector is good. Give it a close visual inspection, and check continuity with multi meter from the pcb edge pins for power to other components on the board
 
clean the board contacts with a pencil eraser or some IPA.
those solder-plated contacts leach out the lead and need cleaning eventually.

i dont know why they couldnt gold-plate them like konami does!
 
Midway boards flex way too much and it causes a lot of components to pop off the board as well as cold and broken solder joints as mentioned above. A bit of some flux and going over the ram chips as well as fixing the board to a flat piece of wood with some screws will keep it flat and avoid a lot of the flexing.
Try that.

Other things to keep in mind are if voltages arent right sometimes you will ge a U63 I believe thats the number Error. All that means is there isnt the correct power going to the board.

Hope that helps
 
I have umk3 that does this, could never really isolate what was the issue, one thing I noticed is if I undervolted it it would boot up.
 
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