In the mid to late 70s, I was one of three engineers at Children’s Hospital and Health Center in San Diego. Besides fulfilling my roll in supporting evoked potential research, I was often called upon to address high-tech issues and problems for the hospital/research facility at large.
One day, I was summoned to a lab that had apparently produced an electronic gender detector. It appeared the computers worked for all the men but not for the one woman in the lab. Her computer would just lock up and not respond to her input. None of the men experienced any trouble.
We looked at lots of possibilities, but none bore fruit, so she used another computer, with no problem. A few days later, I received a call from the lab where I was told that one of the male members of the staff was now having a problem with his computer. I visited the lab and asked what was different about that day. I got the stock unhelpful answer, “Nothing!”
I pressed, “Are you sure? Other than wearing different clothes from yesterday, there must be something?”
I had him remove his shoes and operate the computer in his cotton socks. It worked perfectly. I then asked the young woman to go to the ladies room and remove her stockings. When she returned she slipped off her shoes and was able to use the machine without difficulty.
At the time, all of the men in that lab wore leather-soled shoes. The man who had computer trouble had bought new shoes with an insulating, synthetic sole. Those shoes became sufficiently ungrounded. The woman was wearing stockings and shoes with synthetic soles, so she had the same problem.
Later that day, I tore into the machine and, with some effort, found and repaired a loose ground wire.
This entry was submitted by Dave Ussell and edited by Jennifer Campbell.
Dave Ussell is a graduate of San Diego State University with a degree in physics.
Tell us your experience in solving a knotty engineering problem. Send to Jennifer Campbell for Sherlock Ohms.
Wow, interesting problem to have! The first thought I had when I saw the headline was, "So, if you're in the Hell's Angels, you can use this particular computer?" Clever sleuthing on this one to figure out the problem!
Years ago an IBM typewriter field technician (so you KNOW it was years ago!), kept getting calls from an office where one machine seemed to malfuctioning. But when he tested it it worked fine. He even swapped out the machine, but still the one at a particular desk always seemed to malfunction.
So on one call, the secretary (so you KNOW it was years ago!). Showed him how it malfunctioned. She turned it on, put in a piece of paper, and the typewriter went into fits as her extremely full bosom rested on the typewriter keyboard.
My father was a shoe repairman in the San Diego area. He routinely added a braided ground strap to nurses shoes. They were required for individuals working in high oxygen areas to prevent sparks from igniting a fire.
He would simply take a flat braided wire and punch it through the sole and lay about a 1 inch length inside the shoe and outside the shoe and anchor the ends wth a flat rivet.
A secretary at a company I worked for several years ago would tell people not to walk by on the left side of her desk. One day it was me. When I asked why, she told me her computer would shut down. Not believing her, I asked her to save her work so that I could see if it was true. When I walked past on the left side of her desk, the computer did shut down. I checked to see why, and found an extension cord ran on that side, and the cord was losing connection with the receptacle.
Cabe - I had the same thought. Ground problems manifest in interesting ways. I once spent days chasing an ungrounded pin on an IC that produced a slight capacitive load with an 18 hour time constant that caused the output to exhibit a slight jump. If you need a ground - make sure it is a solid ground!
I was having a look at safety boots at our local work clothing store. apparently there are various specialties including high voltage insulated for electricians and anti-static for electronics techs. I asked if I could a combination of both. It took the guy about ten seconds to say no, that wasn't possible.
Jerry Weinberg (of IBM and "Psyc of Computer Programming" fame) tells a couple of stories:
The first one had to do with women operators having a high failure rate with early IBM mainframes. Remember, these were in carefully controlled computer rooms.
Turns out, the dress code required the women to wear wool skirts and nylon hose. The keyboards would happily conduct those big static charges right to the input boards. The dress code was changed && IBM later beefed up the static protection.
The other one was really weird. The mainframes would overheat in a random manner. Much wailing and nashing of teeth, because the AC and room design was IBM standard. Jerry gets sent to investigate. The operators were nuns, wearing full habits. He noticed a couple standing over the floor grates, then the system overheat warning going off. The nuns were just trying to get cool, but the full skirts were altering the airflow enough.
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