Last summer, our refrigerator stopped working. Alarmed that the entire contents of the fridge may be lost, we moved everything from the freezer to another freezer that was in the pantry. But the contents of the refrigerator were more of a problem. A couple of picnic coolers would suffice for a couple of hours, but not for days.
My son (a student in a university EE program) and I disassembled the rear of the freezer section, and we found the condenser coils frozen, so they were working correctly. The actual cause of the failure was that the circulating fan had stopped. Without the circulating fan, the cold air from the coils does not chill either the freezer or the refrigerator section below. The appliance was crippled.
Thinking the motor bearings might be seized, we took out the motor to lubricate it, and we found that the fan turned easily. It was not the bearings. When we checked the continuity of the motor windings, we discovered that it was an open circuit.
At least now we knew we had to replace the motor. It would take two or three days for the new motor to arrive, and, in the meantime, we would have no refrigerator. This is a big deal when you have four boys living at home.
While I went online to find a replacement for the motor, my son, not knowing any better, decided to unwrap the insulation tape on the motor and see what he could do. The motor has hundreds of turns of fine enameled wire, about 32 gauge, on a plastic core. I figured an open circuit was probably buried under dozens of layers. However, upon removing the tape, my son found an obviously melted wire on the surface of the windings.
I thought this would be a great time to explain to him what happens when a transformer gets one shorted turn. Magnetically, this one turn shorted out the whole transformer, which is why there was enough energy to melt the copper wire into metal balls. The enameled insulation was so thin that the motor vibration must have been enough to chafe the insulation of two adjacent or overlapping wires, causing a shorted turn, which then melted to form an open circuit.
My son did not assume my belief that the motor was ruined, and proceeded to unwrap about two turns in each direction. He asked me to solder it back together. Finally, a light bulb went off. I realized that you can repair small motors if you can access the bad windings, so we soldered the wires back together, and voila! The motor worked again. It had three fewer windings, but out of, say, 300 windings, this is a miniscule change.
We were able to reassemble the refrigerator/freezer and get the food chilling. The lesson? Don’t assume it’s impossible just because you've never done it before. The spare motor arrived three days later. It’s in the shop now, waiting for the next (unfixable) failure.
This entry was submitted by Chris Kelly and edited by Rob Spiegel.
Chris Kelly holds a BS from the University of New Mexico and an MS in computer science from Colorado State University. He has served as a design engineer with Agilent Technology since 1983, and he designs small electronic instruments, such as function generators, and DMMs. He has been named on six US patents in the areas of data acquisition and conversion, instrument calibration, and signal generation.
Tell us your experience in solving a knotty engineering problem. Send stories to Rob Spiegel for Sherlock Ohms.
I just thought of a medical analogy that's apropos. It's like when doctors say, "The patient survived the surgery but died from complications." Sometimes, I admit, it's lack of patience (not "patient") on my part when attempting to repair stuff. But mostly, like you and I have both experienced, Jon, lots of things are designed to be put together and fit tightly, but not to be taken apart and put together again. Humpty Dumpty.
As my neighbors throw out their appliances, they are always so proud of the mountains of cardboard in their "recycle" bins. I, on the other hand, take more of your son's approach. Instead of recycling the box of my new appliance - I "recycle" the appliance - back into a working appliance.
In this day of micro electronics and planned obsolecence we have forgotten the true value of time saved "not shopping", things learned while fixing other things, experience gained by failure, perserverance and patience learned while overcoming the adversity of an un-repairable dishwasher.
Small wonder then that our nation begins to lose it's technological edge as there is no longer the necessity to learn these basic skills, fundimental concepts, and problem solving experience with the ease of a "just replace it" society. (Maybe our kids are just following our example?)
I am constantly amazed when people explain why they can't fix something. "I don't have the tools" (2 screw drivers, a wire cutter and a pliers? $5.99 @walmart) "I don't know anything about it" ( 5min + google). "I'm afraid I'll wreck it more." (said as it's being hauled out to the garbage). "Did you even try to fix it?" (Not really cause I want new model XYZ). "I don't have the time." (But I'll spend 3 hours talking to salespeople and shopping on line and 6 hours working to pay it off + gas and time to drive all over town for the best deal, paying income tax, paying sales tax, paying credit card fees, + supporting Overseas jobs. Oh sure most of my solutions involve 3 trips to my local hardware store - but I consider them more like friends.
We can blame our schools and government for the technological decline in America, but the core problem has to do with our society's attitude and how badly we want/ or need to know something. With the internet and all this country has to offer in libraries, senior citizens, and community education there is no reason anyone in this country cannot learn to do whatever their heart desires to learn, if you don't believe it just ask anyone who comes from just about any other country.
I applaud your article - this story used to be the norm, now it's so rare it merits an article. Thanks for showing us why we need to "keep our hands in it."
While it's great to be able to fix something, these days things aren't made to last and are made rather poorly, as the possibility that vibration may have been able to rub insulation off shows. Stuff like this makes me wary of everything produced these days, especially as price is king, and standards such as ISO 900X, mere window dressing to make people think that the Emporer is wearing clothes.
You're not alone, Alex. I had the same experience with a CD player that held three disks. The small plastic gears were fragile and difficult to get back together. It was easier to buy a new player. Back when cars had carburators I took one apart ro rebuild it and followed the instructions faithfully, but it never worked well. After a while I replaced it.
I've never been facile enough to repair/re-solder bad windings in either a motor or a transformer. The fact that you guys diagnosed the problem is great, but that's only half the problem. The other half is fixing it. I admit that there are many cases where I've figured out the problem, but in attempting to fix it, I've mucked things up worse. A VCR comes to mind, where the plastic gears inside were so touchy that when the thing was reassembled it just wouldn't cycle properly. Sometimes broke is broke.
Good thinking on the young man's part. You never know whether or not you can fix something until you at least take a look. The fans in refrigerators are notorious for premature deaths. A 9-year-old Kenmore at a friend's house has gone through three fans. After the last one went, the fridge got replaced with one that has a higher efficiency and smaller doors that make it easier to open in a small kitchen. Sometimes even though you can fix it, you might have a good reason not to.
Thanks for the note. I think you hit it on the head, impatience. I get driven by cost-effective, efficient use of time, etc, but sometimes the home solution has different parameters than at work. Saving the contents of the fridge was a happy event worth way more than any costs involved. As Beth pointed out, my son's tenacity was more effective than my experience and snap judgement. Maybe that comes from the time he spent watching bugs and enjoying the world through patient, curious eyes!
Great story. When I was younger I did something similar for a dishwasher. I ended up rebuilding the pump motor. It didn't really take too long. As I remember, my father was just too impatient, so my mother sent him outside while I finished the job.
I really do prefer to repair an appliance or machine if it can be done in a reliable way. We have a double oven which developed a problem. I isolated it to a part in the electronic control module. Frankly, I think I could have fixed that myself, but becuase of the high temperatures involved I wanted the module replaced or professionally repaired. We called in the GE (it is a GE oven) repair service. The guy came by, came to the same conclusion as I had, and then informed that the module was no longer made so he could not help me. They did not charge me. The options were to replace the oven or fix the module. Oh, and the replacement units were slightly larger, so we would have to modify the cabinetry. The cost would be about $2K or more. I opted to fix the module. I found that one of the companies that did this was located nearby. I took the unit in myself and they had it ready the next day. We reinstalled it and it works great.
I love the ingenuity and tenacity of your son and the way he choose to ride it out until the two of you could come up with a solution. No doubt a budding engineer! Hopefully, this was a great hands-on learning experience for both father and son, both from a technical standpoint as well as fostering broader problem-solving skills.
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