On-Call Welcome again to festive On-Call, in which we delve into the mailbag of not-quite-worthy-as-standalone contributions to keep the site busy as the world runs out of tech news before Christmas.
Today: Sparky tales of electrical issues.
Such as one from reader "Zeke", a sysadmin for a fleet of a few hundred PCs.
One of Zeke's flock complained that it was no longer possible to remote into her main machine.
"The main computer had just recently been shared and I was confident it should be working," Zeke told On-Call. "So I went to the user's desk and sure enough her shared computer was not online.
"Together we walked upstairs to the main machine and I quickly surmised that it was not turned on."
The user "got a puzzled look and asked: 'So I have to turn it on before I can use it from my other computer?'"
Zeke kept it together: he didn't roll his eyes or sadly, slowly, shake his head.
"Yes" was all that he could muster.
Chipping away at a problem
"Russell" read the On-Call about the elevator that crashed servers and sent a similar tale of working for a bank that had one branch "where nearly every day the server would crash around 2 or 3pm."
Russell told us that after several visits, replacement motherboard and power supplies, he and his team were stumped.
"Until one day a switched-on service engineer was on site, and realised that the branch was in fact next to a chip shop.
"When the deep fat fryer in said shop was switched on the EM spike knocked out our server!"
Good excuse to eat some chips, no?
Solving problems with sound
"Jonah" from New Zealand had a similar problem: he worked for a telco that ran a network of Wi-Fi hotspots, one of which was located in a cafe and kept rebooting.
So Jonah and colleagues visited the cafe, looked around and could see nothing wrong.
But after a while they noticed that the router's reboots seemed to coincide with some humming.
"We looked around and identified the source of the noise – the compressor on an industrial fridge where the cafe kept their food supplies had kicked into life. Curious, we waited for the fridge to cycle off, and then back on again, and each time it started the router would restart."
Jonah once worked "for an appliance manufacturer so I knew that compressors could cause nasty power spikes. We made a quick trip back to the office to collect a UPS, and installed that on the power supply for the router.
"Both of us held our breath as the compressor kicked into life, and this time the router continued to truck along without rebooting."
It later turned out that the manufacturer had become aware of the problem and shipped a better power supply with later batches of the Wi-Fi access points.
That's forked up
"Genevieve" sent us a similar story about "a DEC PDP-11 being used as some sort of controller in a warehouse operation". The computer sat on a small mezzanine above the warehouse floor, to keep it out of the ruck.
Said computer would also "crash from time to time for no apparent reason".
"Tech after tech spent months running diagnostics and poring over log files," to no avail, Genevieve told us. "Until one day day someone noticed that the crashes occurred when a particular forklift passed underneath the mezzanine.
"It turned out that this forklift had some sort of fault that caused its ignition coil to radiate excessive RF noise. The problem was corrected on the forklift and the crashes stopped."
Mind the Gap
"Ashley" had a story for us too, from the time he worked on AS/400s and a user called the hell desk to complain that his computer wasn't working.
"Normal diagnosis methods included asking about the location of block cursors and X and horizontal lines to determine the communications status of the twinax-attached smart terminals," Ashely told On-Call.
He also "asked the user to confirm that the cables were plugged in, and they immediately said yes".
"I explained that he must not have just checked the cables, because he didn't pause but answered straight away, and could he please check properly." So the user put Ashley on hold, seemed to do something and 20 seconds later "came back to say all was well".
Sigh. There was nothing for it but a visit, so Ashley came downstairs to the user's cubicle.
"From three meters away I could see that the power cable was slightly jutting out from the outlet," he told On-Call. "I said nothing, squatted down and pushed the cable in firmly and heard the terminal start up."
He then "walked away without saying a word to him".
"Two minutes later he called and apologised," Ashley told us, with perhaps the hint of not having had many apologies before or since!
What weird faults or bleeding obvious power outages have you diagnosed? Share them with On-Call and it could be you cheering up far-off peers in 2018. ®