Windows said modem worked fine. That unmistakable scorched electronics smell suggested otherwise

Energy can be hard to find on Friday mornings, which is why The Register uses them to offer a fresh instalment of On Call – the reader-contributed column that shares your hopefully empowering tech support stories.

This week, meet a reader we’ll Regomize as “Lachlan,” who told us he once did tech support for a senior exec who had a side hustle writing essays for Japanese university students attending UK universities.

The exec asked Lachlan for help diagnosing a sudden inability to send or receive email, an obvious hindrance to the side hustle.

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This story took place in the dialup age, so Lachlan sensibly assumed that the exec’s modem was misbehaving.

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“I checked the network settings, nothing wrong there,” he told On Call. Next, he checked the cables, and if the line the modem used had a dial tone. Again, all was well.

“At this point I decided to make sure the device was correctly installed in Windows Device Manager,” Lachlan wrote. “I had a lot of experience in the dark arts of serial communications and there was an option in the advanced settings in Device Manager to send a series of low level AT commands to the modem, which would return responses.”

He ran the tests, and Windows reported that the modem was in the pink of health.

With all that done, Lachlan decided the time had come to replace the modem.

“When I opened the PC, I got a faint whiff of that unmistakable scorched PCB smell,” he wrote. “By looking at the modem you couldn’t normally see if any of the chips were faulty. In this case there was a black soot mark in the shape of the voltage regulator chip which sits between the phone line and the sensitive chips on the modem.”

“This was to protect the device from the 70V line voltage BT used to create a phone connection,” he explained. “However, in this instance the chip had been vaporized. That wasn’t just a slight over voltage – this was way higher.”

Lachlan asked the exec when his email had stopped working, and if he could recall any recent electrical storms.

He replied by saying his email stopped working while he watched a really impressive display of lightning.

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“That voltage regulator chip sacrificed itself for the greater good,” Lachlan wrote.

Has Windows failed to find an obvious fault? Or has lightning lightened your load? In either case, click here to send your story to On Call so we can electrify your fellow readers on a future Friday. ®