Fix-it stories
Odd projects around the house
正文
Background
Modern life depends on various gadgets that offer convenience and save time. It's easy to take it for granted until something breaks. It happened to me the other day. I was ready for dinner after heating some leftover food in the microwave. When I tried to shut the door, it popped open and came back right at me. No big deal, I gave it another shove, and it popped open again. It was then that I realized the thing broke. The timing could not have been worse. Having just flown back from a vacation, I had a week all to myself before my wife and daughter returned. My plans included watching movies on DVD, working out, and catching Red Sox games without interruption! To save time, I was prepared to eat leftovers for dinner the entire week and I was heavily relying on the microwave to cook my meals.
The microwave, made by Sharp, was one of the built-in types and is located above my range stove. It provides light over the cooking area while doubling as a hood exhaust system. Having it replaced would mean scheduling an appointment with a technician and wasting precious time. Besides time and money, the microwave would end up in a landfill or worse.
All this because of a broken door?! It was time to roll up my sleeves and do some fixing.
Troubleshooting & Diagnosis
After some reading on the Internet and physically examining the door, I realized that the mechanism is centered on two hooks (Image A) on the door and two slots on the oven (Image B). The hooks can slide up and down but are held down to the bottom by tension. The surface inside the slots has an upward slope like a right triangle lying on its side. As the door closes, the hooks are inserted by the force into the slots, pushed up by the incline, and snapped into place by the tension after reaching the end. The bottom hook also functions as a trigger to turn off the interior light and activate the heating tube as it makes contact with an interlock switch. Once I understood how it all worked, I determined that a loss of tension on the hooks prevented the door from closing.
Repair Procedure
Step 1 I pried open the plastic cover with a flat-head screw driver around the edge of the door until it lifted up enough for me to insert a second screw driver (Image C). Using the additional leverage, I pried carefully until it unsnapped and popped out. At that point, a space opened up enough for me to reach in and I pulled the whole cover off with my hand.
Step 2 As soon as the cover came off, this little plastic piece (Image D) fell to the floor. With the door assembly in plain view, it wasn't hard to tell the piece was originally fused to the base of the door structure to hold down the lower end of the spring. The other end of the spring was latched on the body of the hook piece, spring-loading it to create tension.
Step 3 Initially I was thinking super glue all the way. I dismissed the idea because I didn't have any super glue handy, and I doubted that it would withstand the force even if it would hold initially.
Step 4 (An Aha moment) I was desperately looking for ideas when I came across a piece of leftover wire in the garage. What about having a piece of insulated copper wire in the microwave? I was concerned but I took a leap of faith and the wire became a central part of the repair work. I made a small loop on one end of the wire, threaded through the ring on the spring to form a connection, and wrapped the other end around a sturdy metal part on the base of the door. I adjusted the tension by bending the wire in different places for the wrap around until, well, it felt just about right (Image E). I determined that the piece of insulated copper wire which I inserted is actually located outside of the heating chamber, safely away from the action. Before putting the cover back on, I bench-tested the repair by heating a glass of water and it warmed up in no time.
Final thoughts
What were the design engineers at Sharp thinking when they decided to use a flimsy piece of plastic the size of a pinky fingernail to hold down a tension-loaded spring that expands and contrasts multiple times a day? This is arguably the component that experiences the most wear and tear in the whole oven. Were they trying to set us up so they would sell more? I am just glad that, with the “wire” fix, the door is the last thing that will ever break in this oven. While Googling for information, I realized it is not uncommon for microwave oven doors to fail. Hopefully this repair log can help some else.
Modern life depends on various gadgets that offer convenience and save time. It's easy to take it for granted until something breaks. It happened to me the other day. I was ready for dinner after heating some leftover food in the microwave. When I tried to shut the door, it popped open and came back right at me. No big deal, I gave it another shove, and it popped open again. It was then that I realized the thing broke. The timing could not have been worse. Having just flown back from a vacation, I had a week all to myself before my wife and daughter returned. My plans included watching movies on DVD, working out, and catching Red Sox games without interruption! To save time, I was prepared to eat leftovers for dinner the entire week and I was heavily relying on the microwave to cook my meals.
The microwave, made by Sharp, was one of the built-in types and is located above my range stove. It provides light over the cooking area while doubling as a hood exhaust system. Having it replaced would mean scheduling an appointment with a technician and wasting precious time. Besides time and money, the microwave would end up in a landfill or worse.
All this because of a broken door?! It was time to roll up my sleeves and do some fixing.
Troubleshooting & Diagnosis
After some reading on the Internet and physically examining the door, I realized that the mechanism is centered on two hooks (Image A) on the door and two slots on the oven (Image B). The hooks can slide up and down but are held down to the bottom by tension. The surface inside the slots has an upward slope like a right triangle lying on its side. As the door closes, the hooks are inserted by the force into the slots, pushed up by the incline, and snapped into place by the tension after reaching the end. The bottom hook also functions as a trigger to turn off the interior light and activate the heating tube as it makes contact with an interlock switch. Once I understood how it all worked, I determined that a loss of tension on the hooks prevented the door from closing.
Repair Procedure
Step 1 I pried open the plastic cover with a flat-head screw driver around the edge of the door until it lifted up enough for me to insert a second screw driver (Image C). Using the additional leverage, I pried carefully until it unsnapped and popped out. At that point, a space opened up enough for me to reach in and I pulled the whole cover off with my hand.
Step 2 As soon as the cover came off, this little plastic piece (Image D) fell to the floor. With the door assembly in plain view, it wasn't hard to tell the piece was originally fused to the base of the door structure to hold down the lower end of the spring. The other end of the spring was latched on the body of the hook piece, spring-loading it to create tension.
Step 3 Initially I was thinking super glue all the way. I dismissed the idea because I didn't have any super glue handy, and I doubted that it would withstand the force even if it would hold initially.
Step 4 (An Aha moment) I was desperately looking for ideas when I came across a piece of leftover wire in the garage. What about having a piece of insulated copper wire in the microwave? I was concerned but I took a leap of faith and the wire became a central part of the repair work. I made a small loop on one end of the wire, threaded through the ring on the spring to form a connection, and wrapped the other end around a sturdy metal part on the base of the door. I adjusted the tension by bending the wire in different places for the wrap around until, well, it felt just about right (Image E). I determined that the piece of insulated copper wire which I inserted is actually located outside of the heating chamber, safely away from the action. Before putting the cover back on, I bench-tested the repair by heating a glass of water and it warmed up in no time.
Final thoughts
What were the design engineers at Sharp thinking when they decided to use a flimsy piece of plastic the size of a pinky fingernail to hold down a tension-loaded spring that expands and contrasts multiple times a day? This is arguably the component that experiences the most wear and tear in the whole oven. Were they trying to set us up so they would sell more? I am just glad that, with the “wire” fix, the door is the last thing that will ever break in this oven. While Googling for information, I realized it is not uncommon for microwave oven doors to fail. Hopefully this repair log can help some else.
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