What I Learned About Garage Door Openers

A friend's garage door opener wasn't opening the door although the motor was running. I offered to try and repair it. After all, it already wasn't working; what was the harm?

After opening the cover the problem was obvious. The nylon gear which drove the shaft that drove the sprocket (which is a gear that is driven by or drives a chain), was split in half. I looked up the manufacturer on the 'Net, then the model number and ordered a replacement kit. I was so relieved that it came with a detailed instruction book!

Here's what I learned about this garage door opener:

Limit Switches

The limit switches are very simple. As the drive shaft turns, it drives a screw upon which is mounted a moving contact. As the screw turns, it moves the contact to one end or the other. One screw on each side of the moving contact has the other end of the contact. As soon as the moving contact meets the end contacts -- the door stops. Simple!

Rate Sensor
There is a rate sensor that measures the rate at which the motor is spinning. This was also simple. A cap on the motor shaft had a series of four slots and openings, which passed through a sensor with a tiny emitter and sensor. If the door gets blocked, the motor can't turn. If the motor can't turn and the unit has not hit one of the limit switches, and the door is moving down, the controller reverses direction. If the door is moving up, it stops. Simple!

Retaining Pins
There isn't any other way to get a retaining pin out other than with a hammer. The sprocket drive shaft holds the drive gear in place with two retaining pins. These fit tightly into place. I had to drive the lower pin out in order to slide the new drive gear into place and the only way to do that was with a hammer. As soon as the pin was flush with the shaft, I used a punch to continue driving the pin through the shaft. After the new drive gear was in place, it was hammering once again to get the pin back into position.

Disassembly & Reassembly

Check the orientation of things as you disassemble them. I made two good choice and missed one opportunity. Before unplugging drive motor power connectors, I confirmed that the diagram in the instruction booklet was accurate and took a picture of the setup with my phone. When re-assembling the unit, I had all the documentation that I needed. However, I didn't notice the tabs in the top plate that holds the drive shaft in position and ended up re-installing that plate rotated 1/3 around. I didn't notice the mistake until nearly the very last step of re-installing the protective plastic cap over the sprocket and drive chain. It didn't make sense to disassemble the entire unit at that point, so we're living with my error. Had I taken a picture of that unit before disassembling it, I would have had the necessary reference.

Clean Grease

Clean grease isn't so bad. Dirty grease is wicked icky, but the new clean grease was easy to put on and I didn't mind cleaning up afterwards.

End of the story: the garage door works perfectly now. And I had a lot of fun taking the durn thing apart and putting it together!

Fixing the Kenmore washing machine

My beloved wife said that the washer wasn't working.

"Typical", I thought, "the extended warranty expired about a month ago."

The washer wasn't draining water during the spin cycle. But, hey, my friends had this problem with their front loader a year or so ago. The repair man said that they were using way too much soap; that the front loader needs about half the volume of soap the top loader needs. Detergent bottles and measure are still assuming a top-loading washer (I haven't seen any detergent boxes that talk about the volume needed for your front-loader -- post a comment if you have). The extra soap clogs the outlet valve and prevents the water from getting out. So, armed with this completely inadequate knowledge, I grab a screw driver and start looking for screws.

We have a Kenmore 3.1 Cubic Foot Front Loader. There is a lower front panel with two screws holding it in place; so that's where I started. The outlet from the drum as visible on the right side of the machine when facing it. A rubber tube that connected to two drain points from the drum ran to a small impeller pump and then to the outlet line. Everything was held in place with pinch-clamps. So I pull it all apart. Some soap, hair, coins, pebbles and a few tiny toys, but it really didn't look like enough to stop the machine from draining. Put everything back together and test it. Water in; start the spin cycle, water drains, no spin. Damn; I have to pull off the back panel.

That's about 40,000 screws that don't want to come out. Most of them need some Liquid Wrench and a Vise Grip to get them started. Last thing I want are 30,000 stripped screws. Um; you do know that I'm exaggerating here, right? There were only 4,o00 screws.

The drum looks fine. The belt looks fine, but I pull it off to double check. The drum spins without any catching, grinding or stiffness. The belt has no wear at all. I pull off the motor. That spins with a purr. Back-tracking the wires from the motor, I get to the control unit. That's held in with two screws and has two power and control connectors.

I pull out the control unit and, well, damn. The plastic protective sheet that covers the circuit board has a brown spot in the center. Off come two more screws, so I can lift the sheet and sure enough, something burned out some transistors.

Off to Sears.com to look up the model & buy a new control board for $150 + $20 in enhanced shipping.

Slapped that puppy in and we have clean clothes!

You know what? There is no need for that extended warranty. There is nothing in that machine that I can't fix. Darn that feels good.

Replacing a 1st Gen iPod Nano headphone jack

A few years back, I was lucky enough to win an iPod Nano from the Clock Tower Law Group (because I returned a data sheet at the right time). It was pretty cutting-edge at the time and I really enjoyed listening to podcasts on a variety of subjects during morning runs. For about three months. At that point, it was "borrowed" by kit and kin and I've barely used it since. C'est la vie.

My wife, who is studying voice, relied upon the iPod heavily. She listened to music she was studying, new songs, recordings of her voice lessons, and warm-up routines. She would use the iPod to get her voice work in where ever possible; no small challenge while raising five children. So, when the iPod stopped working reliably, she was at a loss.

The symptoms were that the sound was not coming reliably through both headphone ear buds. I tried swapping headphones, listening to different music and as many other diagnostic comparisons as I could manage. I wish I knew how to put the iPod into diagnostic mode then. (Press and hold the center Activate button + the Menu button until the phone reboots. Then move your finger from the Menu button to the Left Arrow button and press and hold the Activate and Left Arrow button until the diagnostic menu appears. Press Activate + Menu to reboot when done).

Nonetheless, I determined that the headphone jack was defective. I despaired at the thought of trying to pry open the iPod and replace the headphone jack, but since the darn thing didn't work anyway, what did I have to loose?

I googled around for a 1st Generation iPod Nano headphone jack and purchased one for $6 from Binh An at bureenz@gmail.com through eBay. He was very helpful even when I initially purchased the wrong generation headphone jack. I also picked up a replacement battery since I knew I would have the unit open. Mr. Binh included an iPod tool for opening the unit at no cost.

I followed the directions at www.ifixit.com to open the unit and remove the motherboard. The headphone jack is held to the motherboard by a screw and there is a small nipple under the motherboard that fits into a hole in the headphone jack unit. I used a pencil tip on my soldering iron and removed the old headphone jack. I then stripped off as much old solder as possible with some solder braid and cleaned up the entire area by scraping away the solder paste that appeared.

Finally, I put the new headphone jack in place and carefully soldered the four leads to the motherboard. Keep your soldering iron hot and touch the tip to the leads one at a time. Wait a moment before moving to the next lead to let the board cool down.

Then I replaced the battery -- very straight forward compared to soldering the leads of the headphone jack. I used a tiny drop of cryanoacrylate to re-attach the grounding strap before closing up the unit. Make sure the ground strap runs from the headphone jack screw to the back plate.

Check that the little tabs on the metal back plate are all in the proper position before closing up the unit. They're easy to bend when opening the unit.

I charged up the battery and ran the unit through the diagnostics. Everything works perfectly and my wife has her iPod back for less than $20 in materials.

Fixing a Mortise and Tenon Joint

The mortise and tenon joint is a strong and reliable way to keep two pieces of wood together. The Stokke Tripp Trapp chair uses them to keep the angled side pieces connected to the foot pieces.  All of our kids have used Tripp Trapps, or similar, chairs from the time they could sit up right long enough to eat (and were interested in solid food).  From toddler through third grade or so, the chairs brought every one to the table without high chair trays and other barriers.

However, as the kids got older, that mortise and tenon joint would loosen on each chair. Inevitably, I would have to disassemble the chair, glue up that joint and clamp it together.

Well, now we don't need most of those chairs and so we're passing them along. One of the chairs has a pretty loose joint so I bring it down to my shop.  I pull the foot plate off and take a look. Well, now, I had already glued up this puppy quite a few years ago and remembered it well.  

It was the first time that I had seen a tenon that broke off such that part of the tenon remained inside the mortise.  I don't find it a problem to fix a split piece of wood.  All those funny cracks and angles are extra surface area with which to make good contact between the two pieces. Frankly, I was rather surprised that it had failed again.  All that extra wear from folks much older than 8 years old using the chair took its toll and the chair needed to be re-glued.  I rasped off (most) of the old glue, filled it up and jammed the pieces back together.

After the glue set, I put the chair together and noticed that it wobbled pretty badly.  That glue job stank.  The foot board, which has the tenon, wasn't even close to fitting to the vertical with the mortise.  The whole thing needed to be pulled apart and redone.  Back down to the shop.

It took some time and care to chip away the glue and carefully loosen the joint.  

Now I took a close look at that joint.  I fit the pieces together and measured a 3/16" gap.  Oh boy, that's a big gap.

I scraped off more old glue, rasped off a bit of wood that had swollen and tried again.  Nope.  I repeated the process for quite a while.  I got the gap down to 1/16", but no matter what I tried, I wasn't getting a flush joint.  This time, though, I was determined to get a flush joint.

Somehow I needed to figure out why the tenon wasn't going flush into the mortise.  There were doubtlessly high spots on both mortise and tenon that were keeping things apart.

I remembered something my dad, a dentist, did when he was fitting a new bridge or cap onto a patient.  He had these nifty pieces of red and blue paper and he would have the patient bite down of the paper.  Where red or blue was left was where the new tooth was too high and needed to be ground down.  I needed something similar; some way of marking the mortise so that I could see where material needed to be removed.

I took out my shop pencil and generously colored the tenon.  Then, I pushed it back into the mortise and tapped it into place.  The picture below shows the tenon covered with graphite where I first thought the problem may have been.  I later covered the entire tenon with graphite.

Sure enough, when I pulled the pieces apart, inside the mortise and rubbed away from the tenon were the areas that were making contact.  In the picture to the left, you can see the dark marks where the graphite was rubbed off the tenon onto the mortise.  I got out my dremel and rifling files and got to work.

It took a few repeats to find all the offending surfaces and then so smooth everything down to nice finishes.  I would take out the tenon, cover it with graphite from the pencil, tap it into place, pull it out and look for the marks.  Then, using dremel, rasps and sand paper, work down the offending area.  I worked the both the mortise and the tenon in alternating turns so that I wouldn't introduce too much of a gap.  I would rather repeat the process a few times than have a joint with too much space.  No matter how much glue I would then use, the joint would never be satisfactory.

After I repeated the process a half dozen times or so, I was satisfied with the way the two pieces fit together.  It looks like the way it belonged and should have been in the first place.  The final joint is on the right.  Nice and tight.  I cleaned off all the graphite and used Gorilla Glue to fasten everything permenantly and bound the foot board to the riser with to band clamps, one along the bottom of the foot and the other making a right angle with the riser.

Now that will be a nice joint that will take full advantage of the structural strength of the tight mortise and tenon joint and will let the next users of the chair raise their kids on it.