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.
Click here to access the Sherlock archives.