I picked up a 5.8 cu ft Danby keg cooler at a liquidation warehouse for half price. It fits a full size commercial keg, has reinforced steel floor and rack to support it with keg coupler, which I cut off and installed ball lock fittings. I can fit 3 corny kegs at 19 liters each and some bottles at once. The Evaporator coil is a self contained plate at back sealed in anti corrosion coating. I also have an old frigidaire upright fridge that fits carboys and kegs and used to be my front tapped kegerator with a shank through the front door. I keep yeast and bulk hops in there as well . Both work flawlessly.
The chest freezers to watch out for are the ones that have the evaporator coil, which is steel tubing, encased in foam behind the cabinet of the freezer. It wraps around inside the cabinet. You can't inspect it. It's sealed in there invisible to you. The only evidence of imminent failure is rusty water building up inside on the bottom of your kegerator. But even if you can't see it, over time the condensation is working against you because it cannot go anywhere it is trapped inside the foam insulation against the steel tubing. Corrosion is imminent. Steel tubing with trapped moisture against it constantly is not going to last. If you see a coil on the back or outside the unit, that is the CONDENSER coil . That is differrent and changes the gas freon back to liquid before it gets to the compressor.Thats why these units are cheap. There is no need for better materials or configuration as the original working design of these units has these coils constantly frozen; building up frost but not water. It is also very in-efficient to run a unit designed for sub zero temperatures above zero from a refrigeration design point of view. Changing the evaporator design temperature affects the way the freon changes state from a liquid to a gas, straining the system - i.e.- the compressor. If you study making a small refrigeration system from scratch, you will see how although similar to the casual observer,a freezer and a fridge are two very different animals.
A converted kegerator is not a permanent solution to keg cooling. I know it feels great to make one though,I've Been there; but this is a case of a little knowledge actually being worse than no knowledge.