What the 1500W rating means on the bench
The 1.5KE120A A0G: This is a Zener-type TVS diode, not a voltage-reference Zener — it clamps transients, not regulates rails. At 165V clamping, the peak pulse current is 9.5A — that's the current the diode carries during the clamp event, not continuous load. Above that, breakdown starts at 114V minimum. For a 100V nominal rail, this part sits just under the threshold and only wakes up when a spike pushes past 114V.
Package and rework — DO-201 axial
DO-201AA / DO-27 axial, through-hole. The leads are thick enough to handle a hot-air rework cycle without the part walking off the board — just pre-tin the pads, place it, and hit it with hot air from the lead side. The body is large enough that you can grip it with tweezers while the solder is molten; no risk of lifting a pad like you get with a small SMD package. Operating junction temperature range is -55°C to 175°C, so it survives the thermal shock of a soldering iron or hot-air station without cracking the die attach.