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Learning To Fix Stuff, Part 2
Posted By Beth Terry On January 24, 2008 @ 11:47 pm In DIY,Electronics,Fixing things | 10 Comments
On January 2, I reported about my broken plastic hairdryer  and how I was hoping to fix it during my visit to my electronics technician (not “electrician,” there’s a difference I’m told) dad in Hawaii. Well, I’m happy to report that it’s fixed. He was able to figure out what part was bad and knew just where to go to get a replacement. Then, he also knew how to attach the replacement part once we found it. He’s my hero.
After using a screwdriver to take it apart (which I’d already done in the end of December), you need an ohmmeter or multimeter to test the circuitry. As I was attempting to write this post last night, I realized I didn’t know how to explain how my dad used his multimeter to test the wires. So I asked him to send me an explanation, and this is what he wrote:
Switch the multimeter to measure ohms. (Ω)
Two leads (a ‘hot’ and a ‘common’) attach to the plug, the common directly entering the dryer and attaching to one side of the heat coil, the hot connecting to the other side of heat coil thru the switch.
Test the continuity of each lead from the AC plug into the guts of the dryer, measuring the resistance (which should be close to zero) of each. A heat coil has zero resistance to DC but has some resistance to AC, which is why it gets hot, like a light bulb.
When the switch is operated to put the heat coil in series with the two leads from the plug, a resistance of near zero should be obtained on the meter. Finding, instead, a very high resistance (many ohms, over a million) means there is an open somewhere between the two lines. Resistance readings are then measured of each component which is in series with the 2 leads from the plug. This is how it was determined that the thermal fuse had operated (operation of a fuse means it has opened up, stopping current flow).
Basically, his tests revealed that the thermal fuse was blown. A thermal fuse (or thermal cutout) is used to prevent the dryer from catching on fire. If the temperature inside reaches a certain level, the fuse will break and the circuit will be broken so electricity can no longer flow. How does a dryer get that hot inside? If the user has allowed the air vents to completely clog up so that outside air can’t get in and cool it off. So, what I learned is that I need to maintain my appliances (like cleaning out air vents) so that they don’t break in the first place!
By looking really closely, we were able to decipher the specs printed on the outside of the old fuse: 10A, 250V, 113°C. My dad said a new thermal fuse needed to have at least those ratings, but could be rated for a slightly higher temperature as well, if we couldn’t find an exact replacement. Fortunately, having worked as an electronics technician for the phone company in Honolulu back in the 60′s, he knew exactly where to go to get a new one. Precision Radio Ltd.  at 1160 S. King Street has been operating since 1942 (20 years before my dad’s time on the island) and they had just the replacement fuse we needed.
Dad used a soldering iron to make a strong connection between the leads on the thermal fuse and the connectors on the appliance. Michael and I don’t own our own soldering iron, but I checked the offerings of the Oakland tool library , and they do, so if I had to do this again at home, I’d be able to without investing in a new soldering iron. The only plastic I ended up with was the small bag in which the thermal fuse was packaged.
And it worked! The hardest part for me was remembering how to put everything back together again. I’d taken the dryer apart in the end of December and didn’t write any notes about what went where. So it was a puzzle for me, but finally, I got it together and can use it again. (That’s me doing the head upside-down hair drying thing I’ve been doing since Junior High.) Now I can return my friend Mark’s dryer that he lent me until mine was fixed.
It feels so nice to be able to fix what I have instead of buying a new one. It feels like a responsible, adult thing to do. And the throw-away mentality that’s so prevalent these days seems kinda immature to me. Maybe we just need everyone to grow up a bit!
Anyway, the same day we were fixing the hair dryer, my dad got an email from his friend, Derek Hullinger, who was just able to fix his PDA. Now, there’s a challenge! I asked if I could reprint the email here, because I thought it was so cool how determined he was to fix it himself and not trash it for a new one. Here’s what he wrote:
Yesterday, I finally got Weston’s PDA fixed and returned to him! This was a big and exciting thing for me, so I’m going to tell you all about it. I had bought it for him on eBay on behalf of my parents for Christmas, and I felt really bad when it turned out the back light didn’t work. The person who shipped it to me claimed it had worked for her before she shipped it, which it probably did. It’s nearly the same as mine, except that it has a built-in mp3 player.
Weston and I both learned from online research that the back light problem is a common malady for this model, and it was caused by a cable inside being too long and clamping between two metal plates, causing it to break. I found a website (in Japanese) that showed how to repair it, but it required extreme care because there are four parallel wires in a very small cable that each had to be soldered.
Well, we quickly discovered that we couldn’t even get the thing open because it required a special screwdriver with three wings. I found an online company in Hong Kong that sold the screwdriver for 95 cents (including shipping–what a deal!), and we waited two weeks for it to arrive. Then I opened it up and enlisted the aid of a fellow I work with to see if the cable was the cause of the trouble and to fix it. It was indeed broken, but he had trouble with the tiny work and enlisted my boss to help.
So my boss soldered it on Friday and I I went in yesterday to put it back together, only to discover that it still didn’t work! So I opened it up and found that the joint had broken again (my boss had not quite soldered it right–he hadn’t been instructed properly), so I decided it was up to me. I’m not too confident in my own mechanical abilities–I’ve had some real trouble with simple car maintenance things before. But I went at it, and I managed to fix the cable myself. It took a few tries before the solder joints were quite right (I didn’t get a good connection on one of the wires the first time, and I accidentally shorted two of the wires the second time).
On the last try, I hooked everything up and turned the thing on, and it didn’t even go on! I thought, “oh no! I’ve broken it!” But I didn’t have any idea how I’d broken it, and the solder joint was kind of a mess and hard to tell whether one of them was not connected right, so I went ahead and put it the back on anyway, feeling dejected.
Then, when it was all back together, it worked, back light and all! I guess something needed to be in contact that hadn’t connected until it was all back together! Anyway, I was delighted, but I kept turning it on to make sure it was still working. As of this morning, it’s still working great, so I guess everything’s fine! Whew!
These are the kinds of stories we need to hear more of!
Article printed from My Plastic-free Life: http://myplasticfreelife.com
URL to article: http://myplasticfreelife.com/2008/01/learning-to-fix-stuff-part-2/
URLs in this post:
 I reported about my broken plastic hairdryer: http://myplasticfreelife.com/2008/01/learning-to-fix-stuff/
 Precision Radio Ltd.: http://services.worldweb.com/tourism-itinerary.html?mode=add&table_id=1&listing_id=235311&location_level=3:1681&category_level=1:890
 Oakland tool library: http://www.oaklandlibrary.org/Branches/tll_toolsched.html
 Image: https://plus.google.com/+BethTerry
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