I bought the QA403 for the least romantic reason imaginable: I was tired of arguing with myself. Every amplifier I built or serviced, every phono stage I “improved,” every op-amp I swapped — all of it lived in the fog of subjective certainty. A real analyzer ends that argument. It doesn’t care what capacitors you like. It just prints the number.
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The usual first fault in mains-powered electronics is a dead short across the line — a shorted rectifier diode, a blown switching MOSFET, a punched-through mains filter capacitor, a shorted output transistor. Plug that straight into the wall and the only thing standing between the board and a 15 A branch circuit is the device’s own fuse. In the milliseconds before that fuse opens, tens of amps flow. That surge is what turns a one-part failure into a scorched trace, a cracked transformer, a vaporized bond wire in the part you just replaced, and a repair that is no longer worth doing.
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