Need Help With Korean A-One AM-0629 Chassis
 

I am fixing this chassis for a friend and am having trouble. I have deduced that the problem is most likely the voltage regulator however I have no idea which part or parts comprise the voltage regulator.

The chassis is the type that was used as a replacement chassis for 1980’s video arcade games. Unfortunately, no documentation seems to exist for this chassis. The closest schematic I have located can be found Here.

A larger image of the chassis can be found Here.

https://klovimg.com/images/2019/03/17/chas1.jpg

Any help would be greatly appreciated! :)