My MsPacman/Galaga upright has power but screen is black(blank)

I'm assuming this game cabinet was built in the 80's. More than likely, the monitor is an Electrohome GO-7. If this is the case, replace capacitor C511 on the monitor board. It has baked open due to old age. Usually, capacitor kits can be purchased for around 10 bucks, so you might want to replace all the caps on the board at ths time. Worst case scenario would be that the Flyback transformer has smoked (usually you'll see a crack on the side of the transformer), causing the horizontal output transistor to cook and also the smaller of the two pigtail fuses to blow. In this case, you would have to replace the Flyback transformer, the horizontal output transistor, and the small pigtail fuse associated with it. Remember to always discharge the second anode( the suction cup thingy on the side of the tube). It will hold a substantial charge on it. Also, if the small pigtail fuse is blown, you will need to discharge the large cap on the monitor board, or else it will knock you on your rear-end when you try to replace the blown fuse. Hopefully, you'll will only have to replace one cap. C511. If your game does not have an electrohome monitor, I can still help, if you provide the manufacturers info, such as Well Gardner model 7204, or something like that. Good luck!