Claude fixed a 1969 Wurlitzer's hum by diagnosing capacitors from noise frequency

johanze · reddit · 2026-10-21

A Reddit user used Claude to diagnose and fix the hum and crackle in his 1969 Wurlitzer Model 200 electric piano — a great example of AI for hands-on hardware repair:

Audio stethoscope: record a few seconds of noise and Claude identifies the hum type and likely source.
Step-by-step multimeter guidance: which setting, where to probe, what a good reading looks like.
Frequency-based diagnosis: 50 Hz hum meant ripple from the pickup's high-voltage supply; 100 Hz meant main power supply ripple from dried-out capacitors leaking into audio.
Test before soldering: since parallel capacitors add, clip a new cap across the old one with croc leads, record, and only replace if the noise drops. Two small film caps cut 50 Hz hum by 8 dB; of three electrolytics, only one mattered, so only that one was soldered.
Claude read the 1969 service manual and schematics against board photos, picked modern replacement parts, and found them locally ($40 order, $20 actually used). When Claude erred, the next measurement caught it.

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Claude fixed a 1969 Wurlitzer's hum by diagnosing capacitors from noise frequency

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