I'll reply here as we have futzed up your other thread (apologies for my part in that).
FWIW, I don't expect a normal arcade PCB to require more than 150W, but I do not have, nor have I seen, an MK4 PCB. Maybe one of the operator-type folks can chime in and let us know if I am off-base here.
After you clean the edge connectors (I use contact cleaner or alcohol first and, if still dirty, a pencil eraser), if you still have problems, I, like BobA, would suspect voltage problems (which is different from not having a big enough power supply). As BobA points out, some boards like just a little more voltage (not wattage) ... my Galaga likes to run at 5.15V (instead of 5V).
Many arcade switching supplies have a little knob (potentiometer) with which you can tweak the voltage level. Some even have an LED that provides a rough indication of the output voltage. And then some have neither.
HOWEVER, it is always best to use a multimeter and measure the voltages coming off of the power supply and the voltages reaching the board. I STRONGLY suggest that you do this before adjusting any power supply (if you don't have a multimeter, perhaps you can borrow one). There is a sticky post on
How to use a multimeter to troubleshoot that may be useful.
This may seem like a pain, but, if you are going to work with CoinOp machines, it is 100% necessary equipment (and once you have measured voltages a few times, it is just second nature).
If you can provide a picture of your power supply, one of us may recognize it and be able to advise you on adjustment.