600 W peak pulse, 150 V standoff — what the ratings mean for the board
The SMBJ150A-13: No power line protection (no internal TVS structure for AC mains), so this is a signal-rail or DC-bus protector, not an AC inlet suppressor.
DO-214AA SMB — field-swap note
DO-214AA (SMB) package, surface mount. The cathode band is marked on the body — orientation is unambiguous with a visual check, so a field swap without a microscope is doable if you have a hot-air station or a soldering iron with a fine tip. No exposed pad, no thermal-via requirement; the junction-to-ambient thermal path is through the solder pads and the PCB copper area. The SMB footprint is standard — same land pattern as other SMB-packaged TVS diodes, so a BOM swap to a different SMBJ voltage variant (e.g., SMBJ100A) is a direct PCB fit.