Update: stopped trusting the schematic after a bad night in Tucson

Last month I rewired an old King radio in a Cessna 172 and trusted the wire diagram over my own continuity test. Turns out a previous tech had swapped pins 14 and 22, so I cooked a brand new audio panel. Now I verify every pin with my Fluke before I power anything up, even if the drawing looks clean. Anyone else run into a bogus diagram that cost them a part?

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josephl6722d ago

Tucson will humble you real quick, that's for sure. But you might have gotten lucky with the pin swap, because sometimes those old King diagrams are for a different dash layout than what's actually in the plane. I've seen a 172 with the 24-volt setup but a drawing that showed the 12-volt version, and that mismatch alone would have smoked your gear without any pin trickery. Good habit to always trust the meter over the paper, but also worth checking the drawing's revision date and the airplane's serial number range. Those older schematics got photocopied so many times that they ended up matching a hangar queen, not your bird.