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.
My company once dispatched an engineer to solve an intermittenly working cell site issue. He soon figured out it worked when it was raining and stopped when it was dry again. Figuring it was a grounding issue, he rounded the corner outside the building to check the site's earth ground. What he found was a large copper cable stripped at the end lying in a puddle of water. The thing was, the site was mostly operational, as it was in the tropics of Bolivia. A good grounding rod and clamp solved the problem.
I saw a picture of my dad at work at GE in the 60's. I knew he was a manager when the picture was taken - he had a skinny black tie with LONG sleeved white shirt. Before, when he was an engineer, he wore a skinny black tie with a SHORT sleeve white shirt.
One of the things I like about being an engineer: I don't own a tie.
Dress codes; how quaint that sounds today. I must admit that I often long for the days when you could tell the office personel from the janitorial staff by the clothes they wore. Let me be clear, I am not putting down the janitorial staff. There is something disheartening when a man shows up for an interview as anything other than a lifeguard, wearing flip-flops and a T-shirt. It is equally disturbing to me when I see a teacher wearing the same styles as the students, ie torn & faded jeans and the like.
It is amazing what a difference grounding can make. Years ago I swapped out a changer in my console stereo and was shocked to hear a 60 cycle roar drown out any vinyl disc I tried to play. I had just paid big bucks for the changer so I decided to read the instructions (instructions are only for people who do not know what they are doing) and found a note about grounding and viola end of trouble. It seems the original changer had a gounding wire incorporated in the connection which was missing from the replacement.
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.
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.
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!
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.
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