/diy/ - Do It Yourself

Been trying to fix this old AC voltage regulator, tl;dr already replaced some busted components but the thing is VERY sensitive to voltage changes (Supposedly it works 90-130v.)
It's got 3 variable resistors (10k), uppermost I have no idea what it controls, middle controls output (ranging from 110-130v) and lowermost controls the out of range protection mode (had to turn it all the way down, else the OR mode will kick in all the time.) I've messed with these to no avail, still finicky, can't turn any appliances on or else this thing will go into OR mode when the main goes a bit under 120v.