March 10, 2026
When Crystals Take a Spin Cycle
TCXO Failure Analysis
The $2 clock that broke a fancy scope — commenters blame the ultrasonic ‘carwash’
TLDR: A tiny $2 clock chip in an open oscilloscope died, throwing measurements off until it was replaced; commenters think an ultrasonic cleaning bath may have killed it. The thread exploded with shop-floor rules, from “never wash oscillators” to “don’t snip leads hard,” mixing TILs and memes with hard-won experience.
A two‑dollar clock part brought an open‑hardware oscilloscope to its knees, and the internet had opinions. In the write‑up, a lab test showed a 100 MHz signal showing up around 106 MHz, then a dead 10 MHz “TCXO” — a tiny temperature‑stabilized clock — was found and swapped, fixing everything. The likely culprit? An ultrasonic clean, a buzzy bath used to wash boards.
Veterans stormed the comments to say never dunk oscillators. One pro flatly warned, “you’re not supposed to sonic wash anything with an oscillator,” while another added it’s right there in the datasheets. Meanwhile, newcomers had a “today I learned” moment — and a price shock: the fragile hero costs about $2.
One engineer claimed even trimming leads before soldering can jolt a crystal to death. Another explained a neat design trick: divide the frequency by two so a smaller crystal fits the tiny can. And yes, everyone chuckled at the “sketchy” Back Room FA Lab name.
Comic relief bubbled up fast: commenters joked about giving crystals a “spa day” and putting clocks through a “spin cycle.” But beneath the memes, a clear message rang out: a cheap timekeeper can sink expensive gear — and cleaning habits matter.
Key Points
- •Testing a ThunderScope PCIe prototype revealed a 6.6% timebase error: a 100 MHz input appeared near 106 MHz and 10 MHz references read as 10.665 MHz.
- •The ADC clock generator’s PLL lock bit indicated it was not locked.
- •The 10 MHz TCXO (ECS‑TXO‑3225MV‑100) output was flatlined, causing the PLL’s VCO to free‑run and the 1 GHz ADC clock to hover around 938 MHz, unstable.
- •Reworking solder joints did not resolve the issue; replacing the TCXO restored normal operation.
- •The article explains TCXO function and notes ultrasonic cleaning of boards with oscillators as a known risk; deeper failure analysis is forthcoming.