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Sherlock Ohms

Beeping Oven Called for a Debugging

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tekochip
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Ieeew
tekochip   1/31/2013 10:03:05 AM
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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.


Elizabeth M
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Re: Ieeew
Elizabeth M   1/31/2013 1:05:24 PM
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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.

Charles Murray
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Re: Ieeew
Charles Murray   1/31/2013 6:42:03 PM
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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.  

jmiller
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Re: Ieeew
jmiller   1/31/2013 9:52:28 PM
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.

GTOlover
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Re: Ieeew
GTOlover   2/1/2013 9:22:40 AM
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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!

Analog Bill
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Re: Ieeew
Analog Bill   2/1/2013 12:17:45 PM
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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 ...

Tim
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Re: Ieeew
Tim   2/2/2013 7:16:11 PM
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Buttons and options can be difficult. On our GE front loader, a certain button combination will lock the control panel. Unfortunately, this option is not shown in the manual and required a service call by a technician to show me how to reset the lock.

jmiller
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Re: Ieeew
jmiller   2/2/2013 11:41:41 PM
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I don't understand why the industry can't realize that the american consumer just wants something that is easy to run.  I really don't need 17 different cycles to wash my clothes in.  I do want to be able to lock it out so my child doesn't accidently run the cat through the wash, but I don't have a PHD in unlocking my washing machine.  Is it really that tough.

Ann R. Thryft
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Re: Ieeew
Ann R. Thryft   2/4/2013 12:52:22 PM
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I agree with jmiller. And doesn't anyone who designs user interfaces on appliances ever use them? If they did, how could these interfaces (aka buttons, touchpads, knobs, etc) be so bad?

tekochip
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Re: Ieeew
tekochip   2/4/2013 2:34:04 PM
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Ann, when I was designing appliances I would sit down with the marketing guys and have them press buttons on a sheet of paper.  I would have them step through the keystrokes needed to implement what they had specified, and often times their fingers were doing a dance that looked like a version of "Twister" made for hands.  If the feature they wanted proved too complicated they would sometimes add a special button or knob just for that feature.  From their standpoint, now the nifty new feature was advertised because the consumer would see that feature button right on the front panel.


Ann R. Thryft
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Re: Ieeew
Ann R. Thryft   2/5/2013 11:47:25 AM
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tekochip, sounds like you did a much more thorough job of designing--and testing--those interfaces than some of the examples we've heard about here. I like your "Twister" description--makes it easy to visualize.



jmiller
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Re: Ieeew
jmiller   3/26/2013 8:30:51 PM
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I was actually told by one of these "marketing" people that the American consumer will like what we tell them to like.  Therefore, they had the right to tell us what to make because the consumer would like it.  Funny how often the consumer doesn't necessarily like what they are told to like.

Ann R. Thryft
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Re: Ieeew
Ann R. Thryft   3/27/2013 12:22:44 PM
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jmiller, I remember being told exactly the same thing back in the 90s, but as a member of the press. What arrogance. Also, in many cases, how inaccurate. Also, thanks for the info about the touchpad. That's what my husband said. Of course, the answer is infuriating, because that means we can't fix it ourselves and basically, we've been given a poor design and told to live with it.

Cabe Atwell
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Re: Ieeew
Cabe Atwell   3/27/2013 5:42:08 PM
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On a related note, I have cut out the speaker on a few devices over the years. It started with removing the "pc speaker" some decades ago. Those were horrid when the PC would have issues.

C

Ann R. Thryft
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Re: Ieeew
Ann R. Thryft   3/28/2013 2:22:20 PM
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I'd love to be able to do that, in particular to get rid of car noises that tell me the door is open (duh) or the seatbelt isn't fastened (duh again since I'm OCD about that item). For PC noises, I've always just disabled the sound in the control panels. At least on the Mac you can easily do that, don't know about a Win machine.

jmiller
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Re: Ieeew
jmiller   3/31/2013 11:33:08 AM
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I will warn people because I'd hate for someone to try and fix something and not be able to get it back together.  However, often if you can get the touch pad out of any machine and then take it apart you will find the plastic parts, springs etc. inside the machine and these can be modified to solve the issue.  For instance if you are getting a stuck button error message you can shave off a little plastic to provide some clearance and prevent the stuck button.  Be careful not to shave to much.  You really can't glue plastic shavings back onto a spring.  If there is a button that will not push you can use a peice of tape or a sticky note as a shim by placing it on the bck side of the touch pad.  Just some of the tricks of the trade to get machines out the door when the parts aren't exactly what you ordered.

Ann R. Thryft
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Re: Ieeew
Ann R. Thryft   4/1/2013 3:09:50 PM
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Thanks, jmiller. I forwarded that info to my husband for dealing with our oven--maybe. He works in the paint department of a hardware store. He says the controls for his paint mixers have gone from standard toggle switches (and pot dials) over to touch pads. Where once he could change out a switch, he is now "stuck with the infernal pads." The springs weaken, but worse, the electronics board on which they rest stared to flex backward over the years. When the first repair tech came through to deal with this problem, his "solution" to an inoperable pad was to cut a hole in the plastic which overlays the button to grant the switch more travel. Eventually, my husband says he glued little plastic bumpers to the buttons to be able to use them at all.



Cabe Atwell
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Re: Ieeew
Cabe Atwell   2/8/2013 4:58:03 PM
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On another note, the "beeping" sound of common appliances need to be toned down. I once took apart a microwave and removed the speaker for that reason. A volume control is a must. Also, remove the last beep of the warning cycle is key.

Just Like Father Guido Sarducci said about the birthday song, it's too long. Remove the second "happy birthday to you," and it's tolerable.

 

C

Charles Murray
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Re: Ieeew
Charles Murray   2/8/2013 6:09:42 PM
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I'm quite confident that you're the first person to cite Father Guido Sarducci as a source of insight on Design News blogs, Cabe. Great point.

Cabe Atwell
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Re: Ieeew
Cabe Atwell   2/14/2013 11:28:17 PM
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It is an honor and a privilege to site Father Guido Sarducci. I am glad to be the first.

However, beeping appliances need to go. Our cell phones do not have annoying beep ringtones at defaults anymore, why not the microwave?

C

jmiller
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Re: Ieeew
jmiller   3/26/2013 8:52:01 PM
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I agree.  There has to be someone out there that can make the microwave, washer/dryer, dishwasher not beep so darn loud or with such an annoying chime.

Ann R. Thryft
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Re: Ieeew
Ann R. Thryft   3/27/2013 12:22:00 PM
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I agree about the beeping appliance volume control. However, I need to point out that annoying cell phone beeps have now been replaced by someone else's annoying idea of "music."



Ann R. Thryft
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Re: Ieeew
Ann R. Thryft   2/6/2013 2:54:26 PM
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When I first got an oven with one of those touchpads, I was happy--thought it was cool. Now, 10 years later, it's failing--you have to push harder and harder to activate the contacts underneath. Sometimes the timer just doesn't work, since that's the function I use at least once a day.

jmiller
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Re: Ieeew
jmiller   3/26/2013 8:39:56 PM
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It's interesting how when you look underneath those touch pads it's just the same plastic pieces behind the membranes.  Unfortunately, the mechanical spring has been removed and without a good ole metal spring the plastic just can't handle the lifetime load.  I guess someone should have realized that plastic deforms when it gets a little warm and without a metal spring the buttons going to quit working.

Tool_maker
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Re: Ieeew
Tool_maker   2/6/2013 1:16:27 PM
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@Elizabeth: You find it hard to believe that a bug could be the source of the problem. I saw an ant colony bring an M-1 tank to a standstill. It had nothing to do with engineering and I hope the editors see fit to let this story fly.

  We were on an operation in the jungles of Vietnam and my Armored Personel Carrier was following behind a tank as it busted brush. It approached a tree with a large cluster of red/orange leaves, that appeared to be dead. When the tank hit the tree, the red/orange fell out of the tree and covered a good portion of the tank. It wasn't leaves at all, but a colony of army ants. The ants quickly began biting any warm body they contacted, which was about 6-8 soldiers in and on the tank. Now if you were dealing with just a few it was no big deal and you could swat them off, but when there were hundreds the pain was unbearable. They quickly got under your clothes and the only thing to do was get out of the area, get out of your clothes and start beating them off.

  So here sat the tank while the whole crew bailed out and off the tank pulling off their clothes while swatting ants off each other while jumping and screaming. You would be amazed at how fast those ants and their victoms can move. I saw one guy pull everything off without undoing a button or zipper. After the fuss had settled we poured diesel fuel around on the surface of the tank which seemed to solve most of the problem, but periodically for several hours we heard yelps and saw swats as the tankers discover ants not detered by the diesel fuel.

  So when someone tells me a bug can mess up the works, I remember  when I saw them stop a machine of war.

Ann R. Thryft
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Re: Ieeew
Ann R. Thryft   2/7/2013 12:14:43 PM
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Tool_maker's story made me sit up straight. The possibility of the "bug" in a system being an actual bug is an old joke in electronics. It's a joke because the actual occurrence is more than a pun, and has actually happened, according to my tech support friends back in the day.

Constitution_man
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Re: Ieeew
Constitution_man   2/1/2013 12:32:13 PM
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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.

garysxt
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Re: Ieeew
garysxt   2/5/2013 9:01:27 AM
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My uncle was in the Signal Corps in the Pacific in WWII. He used to tell me about how the rats would try to get into the transmitters to get warm and dry out. Of course the results of a rat getting across a several KV plate supply is somewhat more spectacular than an insect across a low voltage switch.

GV
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Re: Ieeew
GV   2/5/2013 5:09:45 PM
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what about fried snakes around a substation transformer in the jungle? that's priceless xD

MD17
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Re: Ieeew
MD17   2/1/2013 4:51:02 PM
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Having once worked repairing computers in the back woods of Papua New Guinea, I can attest to the fact that "Raid Kills Computers Dead!".  A client had a colony of ants take up residence in his computer, entering and exiting through the ventilation holes.  He gave them a shot of Raid through the vent holes and left it to air out.  The next time he powered up, all the magic smoke escaped from the computer.  In due course I received the remains (of both the computer and the ants).  At least this particular variety of Raid was both conductive and corrosive and did a real number on the PCB.

Cabe Atwell
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Re: Ieeew
Cabe Atwell   2/1/2013 5:30:28 PM
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Haha! A true bug in the system.

Most people would have just turned off the electronics of the stove to never use them again. Glad your went above and beyond. That isn't an obvious reason for failure either...



Charles Murray
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Re: Ieeew
Charles Murray   2/1/2013 7:15:41 PM
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I agree, Cabe. This author was impressively determined.

robatnorcross
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Re: Ieeew
robatnorcross   2/1/2013 8:18:06 PM
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A friend of mine was visiting another guy one saturday morning and his friend remarked that his power bill was about zero the month before. My friend (a EE) said they should check to see if the meter was turning. Sure enough a moth had expired and was stuck in the meter works. My friend banged his hand on the meter and the bug fell out as the home owner screemed "OH No".

Tim
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Bugs
Tim   1/31/2013 6:45:25 PM
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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.

notarboca
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Country Life
notarboca   1/31/2013 8:42:25 PM
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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.

Charles Murray
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Re: Country Life
Charles Murray   2/1/2013 7:14:27 PM
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I recall the issue of the fire ants, notarboca. Some time in the last 20 years, a linear accelerator was planned for Texas (I believe it was eventually built there), but it ended up getting bogged down in debate about fire ants. Apparently, some engineers believed that the accelerator's large magnets would attract ants.

Ratsky
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Re: Country Life
Ratsky   2/4/2013 4:07:44 PM
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I had a similar experience when I lived in the Dallas TX area.  My house had a LV lighting system (12VAC) around the exterior and walkways.  There was a 300VA or so transformer that fed the system, with 2 separate outputs (dual secondaries on the xfmr).  I started having intermittent outages on some lights, but the bulbs were OK.  There wasn't much voltage at any of the fixtures on one of the outputs.  I traced the apparent short down to a specific point (all wiring as buried so I really wanted to only have to excavate where the problem was likely to be) by locating the first fixture that had minimum VAC at it.  I started to dig, and was quickly attacked by a bunch of fire ants!  After I did away with them (took a full day for all to die), I dug down and found their nest had been located surrounding a splice insulated with some badly chewed away electrical tape.  Thus a short between the conductors was created.  Unfortunately, the long-term overload had weakened the one secondary; a couple of weeks after the wires were re-taped (very heavily!), that secondary winding opened up.  I sent it back to the manufacturer, who was amazed that the primary protection hadn't tripped, and so the fusible link inside the winding had opened.   The resistance of the wiring to the short location was apparently just enough to let the winding overheat without tripping the circuit breaker in the transformer primary.  They sent me a brand-new transformer at no charge!  When a similar outage occurred some time later, I concluded that the ants really loved the AC field (maybe got high on it!), and made future repairs with even more protection on the splices.

jnissen
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The bugs had little to do with the beeping
jnissen   2/1/2013 2:16:22 PM
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This is a known issue with GE branded ovens. I had the exact same beeping and strange issues a couple years ago. The fix is has become famous as many thousands of folks have fixed their oven with a couple simple pieces of paper. In my case the paper fix did not fix the errors and a new front panel was required to eliminate the beeping. The timer board was just fine - only the tactile feedback button assembly.

The fix in more detail

http://fp1.centurytel.net/Powerman/Dreaded%20F7%20Problem.pdf

 

In this case the bugs were likely just an additional added distraction. Normally bug bodies do not become conductive unless the voltage is high enough. I've had A/C units not start from wasp bodies shorting across the run cap!

Tool_maker
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Poor Mix
Tool_maker   2/5/2013 12:38:22 PM
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  Anytime one of these stories concerns food preparation and bug in the same story it gives me the crrep. I also do not like mebrane covered buttons and much prefer a keyboard type setup.

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Sherlock Ohms highlights stories told by engineers who have used their deductive reasoning and technical prowess to troubleshoot and solve the most perplexing engineering mysteries.
Sherlock Ohms highlights stories told by engineers who have used their deductive reasoning and technical prowess to troubleshoot and solve the most perplexing engineering mysteries.
Sherlock Ohms highlights stories told by engineers who have used their deductive reasoning and technical prowess to troubleshoot and solve the most perplexing engineering mysteries.
Sherlock Ohms highlights stories told by engineers who have used their deductive reasoning and technical prowess to troubleshoot and solve the most perplexing engineering mysteries.
Sherlock Ohms highlights stories told by engineers who have used their deductive reasoning and technical prowess to troubleshoot and solve the most perplexing engineering mysteries.
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