Quoted from CrazyLevi:Fuses would be first. Especially the line fuse. Don't mess with these when plugged in obviously.
This could also be bad fuse holders. Bally's light sockets, Fuse holders, and jones plugs are all absolute shit - I believe because unlike other companies they made them in-house. Without exception, a Bally game of this age needs the fuse holders replaced.
I had a "no power" problem on a Gottlieb once, just turned out the cord/prong was bad (it looked absolutely fine). So you never know. Also make sure the outlet you are using actually works (plug in a lamp or something)
+1 Bally fuse holders suck. Here's mine on my Old Chicago before I replaced it:
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& after:
IMG_7048 (Medium) (resized).JPG
Also, the white/green wire connection on the jones plug that's mounted on the tilt board is ALWAYS toasted:
IMG_7040 (Medium) (resized).JPG
IMG_6936 (Medium) (resized).JPG
I simply bypassed the jones plug on this one wire & used a single heavy duty molex plug/socket to make the connection.
Also, ALL of the light sockets are garbage on this era of Bally pins, do yourself a favor & just replace them all to start with. Flickering bulbs suck.
Another thing, the "over the top" relay on the bottom board should have a # 455 flashing bulb, not a standard 44.