What the 1500W rating means on the bench
The 1.5KE12C-E3/73: The bidirectional channel means it clamps both polarities with one device, saving board space over back-to-back zeners. The 10.8 V minimum breakdown voltage and 9.72 V reverse standoff put this squarely on a 12 V nominal rail — the TVS stays out of the circuit until a surge pushes the line above the standoff threshold.
Obsolete — sourcing reality for the 1.5KE12C-E3/73
No official successor order code is recorded from Vishay. When a TVS in this footprint goes obsolete, the practical move is to cross-reference the 1.5KE12C against other 1500 W bidirectional parts in the same DO-201AA package from Littelfuse, ST, or ON Semiconductor — the parametric match is the clamping voltage and the 10/1000 µs pulse rating, not the brand.
Board-fit and package note
The DO-201AA (also known as DO-27) axial-lead package is a through-hole part — the leads insert into plated through-holes on the PCB and are soldered on the opposite side. Lead spacing is typically 0.375 inches (9.5 mm) centre-to-centre, and the body diameter is about 0.210 inches (5.3 mm). The scorch mark on a dead board often points right at this package when a surge exceeded the clamping capacity. Tape and box (TB) packaging means the parts come in a box with the leads oriented in a tape carrier, not a reel — fine for hand assembly or low-volume rework but not for automated pick-and-place. The axial format is straightforward to hand-solder; just pre-form the leads to the hole spacing before insertion.