On New Year's Eve, I was cooking fillet steak for a party with some friends. I first put it in the pan to sear it and then in a hot oven for a few minutes to finish it. As I was pulling it out, a beeper in the oven control panel started screeching. As the steaks were done and there was nothing obviously wrong with the oven, I simply turned it off at the fuse box and went on to eat the steak and ring in the New Year. I switched the oven on again prior to going to bed, but about two hours later it started beeping. I crawled out of bed and switched it off.
In the morning light, I switched the oven on again. Sure enough, a couple of hours later, it started beeping and none of the buttons would quiet it. I deduced that if the beep started with a cold oven after a couple of hours then it was unlikely to be an over temperature alarm and was most probably a time out -- i.e., the timer had counted down to zero. I switched it on again to observe pre-beep performance.
This time I noticed that the clock button, which was a plastic sheet over contacts on the faceplate, did not set the clock mode but did activate the timer in the same manner as the timer button. Then I perceived a slight bump in the plastic over the clock button icon. At this point I could deduce that something, possibly to do with the bump, had somehow jammed the clock button and set the timer counting down.
I then removed the front panel of the control unit. The plastic sheet covering the front panel had a transparent area over a slot behind it, which was where the clock display was mounted. And the slot was just over the row of push buttons. Just at the edge, where the plastic covered the slot, I saw the dessicated cadavers of some tiny insects.
I shook those out, inverted the faceplate, banged it on the table, and for good measure, ran a piece of paper between the plastic and the faceplate. Several bits of exoskeleton showered out.
After reassembly, the oven worked perfectly, and I now know what debugging means!
This entry was submitted by Phil Hughes and edited by Lauren Muskett.
Phil Hughes is CEO of Clustered Systems Company Inc.
Tell us your experience in solving a knotty engineering problem. Send stories to Jennifer Campbell for Sherlock Ohms.
Sometimes the "bugs" have hair and a hearbeat. A grain dryer I repaired years ago... was reported, strangely, to have all the insulation missing from its wiring inside a control module. When I arrived and removed the cover, the report was correct, but failed to mention the skeleton of a mouse laying in the bottom of the box, along with a pile of colored PVC fragments located, more or less, where the little critter's stomach would have been at the moment of death. The little dude had eaten all the insulation off the wiring with his little chisel teeth, probably could not crawl out due to his increased girth from a belly full of nondigestibles, and simply expired there in the box. When the farmer came out to "power up" the console weeks later, arcing immediately kicked the controller off, and he called me. I rewired the box with XLPE wire [mice don't like XLPE] and it ran great after that.
I could rant for hours about how the current generation of appliance designers are completely out-of-touch with the actual useage of their products. My experience with an Amana range has sworn me off that brand forever. Within months of purchase, the plastic trim at the oven vent had become so embrittled that it literally crumbled away. Gee, you think the designer considered that it might get hot there? Duh ... try 400+ degrees! Of course, letters to them went unanswered ... and even worse, replacement parts were not available from the "factory".
My experience with bugs takes me back to working in the radio-TV repair shop for a huge department store in Florida (remember when radios could actually be repaired?). Opening the cabinet would often release a half-dozen huge cockroaches that would scurry across my workbench (they seemed to especially like to feed on paper speaker cones) to be "re-discovered" another day. I always kept a can of aerosol contact cleaner (in those days, TV tuners contained big multi-wafer rotary switches that, especially in Florida's climate, required periodic cleaning) on the bench at the ready ... it killed the critters pretty quick! I now live in California ... you couldn't pay me enough to live in Florida again! Bugs are just one reason ...
I have a microwave that has a fly stuck between the front window and the metal screen. It was alive for about 3 or 4 days and died. Its carcass is visible in the bottom ledge. For the life of me, I cannot figure out how it got there and will not take apart the door to get it out. I figure this is way to important to mess up the door and get overexposure to microwaves.
At least I did not have teko's experience. I think I would have tossed the control out the door if the surface was moving!
Gross. But interesting. I have heard of similar experiences with other appliances. Buttons getting stuck. Why do I need so darn many options. I don't need water in my fridge. I don't need 15 different cooking cycles and I really only want to have one washer and dryer cycle. Quit giving averything so much extra stuff that can break and design me a dependable appliance that lasts a long time so I can buy it.
When I lived on some acreage in the country, I discovered fire ants are extremely attracted to voltage. Telephone stopped working; telephone box outside packed with them. Air conditioning contactor would occassionally have to be sprayed as well. I learned something new every day.
Bugs do seem to get in the most inopportune places. I am sure the original design review for the stove didi not include "How do we stop bugs from getting in the controls?" Good sluething and not just throwing out the stove for a new one.
History repeats itself. Here's an explanation of where the term "bug" came from in the computer world (from Wikipedia): "Operators traced an error in the Mark II (computer) to a moth trapped in a relay, coining the term 'bug.' This bug was carefully removed and taped to the log book. Stemming from the first bug, today we call errors or glitches in a program a bug." The orginal incident occurred in 1946.
That indeed is a true case of debugging. I don't think I would have imagined that could be the source of the problem, so that's some pretty good sleuthing on your part! What a small thing to cause such a racket. At least the constant beeping didn't ruin your New Year's Eve.
I used to design agricultural electronics and the goods would come back from the field covered in grain dust and, shall we say, other barnyard commodities. One day I was pulling a keypad off of a unit and I noticed that the grain dust was moving in-mass like the tide rolling in on the beach. It turned out that the dust was really very small insects all moving together. From that day on I kept a can of Raid on bench right next to my soldering iron and used it time and time again.
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