27 V Zener — the scorch mark tells you
The 1N6010B is a 27 V Zener diode rated for 500 mW continuous dissipation in a DO-35 axial package — the sort of part that clamps a rail or provides a local reference on a board that sees temperature swings from -65°C to 175°C. Reverse leakage is spec'd at 100 nA max at 21 V reverse voltage, and the impedance (Zzt) is 70 Ohms at the Zener test current — numbers that matter when the diode is holding a bias rail for an op-amp or ADC reference.
Obsolete — what that means on the bench
For a repair bench that sees a dead rail and traces it to a shorted Zener, this means the replacement comes through independent surplus channels, not the factory. Quantity and pricing confirmed at RFQ.