Windows Said Modem Worked Fine. That Unmistakable Scorched Electronics Smell Suggested Otherwise
The Register, Friday, October 23rd, 2026
On Call: Windows diagnostics gave a dial-up modem a clean bill of health, but a vaporized voltage regulator told the real story.
In this On Call column, a reader recalls supporting a senior executive whose email stopped working in the dial-up era.
Network settings, cables and the phone line all checked out, and low-level AT command tests in Windows Device Manager reported the modem was healthy.
When he opened the PC to replace it anyway, he smelled scorched circuitry and found a soot mark where the voltage regulator protecting the modem from the 70V phone line had been vaporized.
The executive confirmed his email had stopped during an impressive lightning storm, and the chip had sacrificed itself to save the rest of the machine.