Tuesday, February 15, 2011

A quick and easy guide to house wiring

Ever get confused about which wire goes where on a light switch? An outlet? Two outlets linked together. Two switches that turn on the same light?

I stumbled on an amazingly easy-to-follow explanation at The Circuit Detective website.

It includes an all-purpose diagram showing how your home is wired (or should be) and a great explanation of how 3-way light switches work.

The site also includes some easy-to-follow troubleshooting steps and, um, some poetry.

The stuff about electricity is really good.

Monday, January 10, 2011

Flush your problems away, literally

Thomas Crapper, who did not invent
the flush toilet.
The biggest fallacy in toilet technology has been the erroneousness concept that "one flush fits all."  It doesn't.  Never has.  You know it.  I know it.  The venerable Thomas Crapper knew it.  Venerable, really, see the logo below.

Actually I'm not certain that he knew the fallacy.  I'm conjecturing it based on his false claim to have invented "Crapper's Valveless Water Waste Preventer (Patent #4,990)."  The patent wasn't his.

Speaking of erroneous information surrounding the venerable Mr. Crapper, it turns out that he didn't really invent the flush toilet.  He just "popularized," it.  Don't even try to picture that.

More improbably, he also, it turns out, isn't the origin of the word "crap."  Wikipedia notes that it's in the Oxford English Dictionary of 1846, more than a decade before he founded his company and several decades before he became famous.

Was he familiar with the OED entry?  Did it steer him toward his career?  Did it inspire his famous 165 mile walk to London to apprentice with a master plumber?

Ever notice how fascinating Wikipedia becomes when you're facing a household project?

The project I'm onto, and the inspiration for this crap, is fixing a toilet that in turn, doesn't flush, overflushes and overflows, doesn't fill, fills constantly or otherwise disturbs the harmony of our home.

It's even cost us a demerit from the municipal water utility.  Seriously.  We got a notice that our "pattern of water usage" indicates a leaking faucet or possibly defective toilet valve.  That's absolutely true. I didn't know they were watching.  Or that they had the technology to detect that.

If the Dept. of Homeland Security ever teams up with our city utilities division, terrorists will throw in the towel.

It's not that I've ignored the problem.  I never did, and I moved from not ignoring it to becoming obsessed with it after one toilet-related incident forced me to patch the ceiling in the room below.

The trouble is, nothing seemed to work.  I'd fixed the mechanism many times and even replaced the entire innards.

Now I've moved to an advanced technological solution that promises to solve multiple problems all at once.

It's called the HydroRight dual-flush system.

I'm going to jump right to the "dual-flush" part because it's so exciting. The term (dual-flush) is a little vague, so I'll explain it.

It doesn't flush twice, if that's how you interpreted it.  It makes your first flush more accurate.  Yes, it moves us beyond the "one-flush-fits-all" era.

The dual-flush system has two flushes: flush number one and flush number two which, conveniently align with another number one and number two, which gets to the point of the system.

Sometimes when you use the toilet you don't really need a full flush.  Other times you do (need a full flush).  I can never remember which is No. 1 and which is No. 2, but you get the point.

The dual-flush flush button, which replaces your current lever, lets you pick your flush.  The bulbous button on top releases the mini, water-saving, flush.  The rest unleashes the full torrent.

The key to its operation is the tube.  It has two ports for releasing water from the tank into the bowl.  The upper port releases just a little bit of water.  The lower one releases it all.

The dual buttons control which port gets used and they do it all mechanically, with cables that run inside a sheath from the button to the flusher, like the cable that tightens the brakes on a bicycle.

Yes, it can be a bit confusing to visitors who may not be up on the latest toilet technology.  We don't put on airs (e.g. "Oh, are you still using a single-flush system?), we just let them figure it out for themselves.

Sunday, December 19, 2010

Singer Serger Repair

My wife's Singer Sewing Serger stopped starting.  Weird way to put it, I know, but when you have three s's in a row, how can you stop?

A serger is like a sewing machine, except that instead of sewing it, well, serges, I guess.  Whatever it does, it stopped doing it just as my wife was finishing off a Christmas gift she was making.  And mailing, after it was finished.

The trouble, it turns out, wasn't the machine itself, but the foot pedal that turns it on and adjusts the speed.  And the serger hadn't completely stopped working, it was just coming on and shutting off randomly after she depressed the pedal.

Taking Apart the Pedal
The pedal is easy enough to take apart.  The top slides over the bottom.  On on end there are two bars that hook together and keep the pieces from springing apart.  On the other end, it's held together by two protrusions on the bottom that snap into holes on the top.  I just pried next to the protrusions to pop them out of the holes.

Yeah, it did seem like it could break, but it didn't.

Inside there's a printed circuit board with a lever switch, a potentiometer and a few other parts.  It's a pretty simple mechanism.

How it Works
As you push down the pedal, a wedge (see last picture) on the top part pushes down on a roller attached to the slider of the potentiometer, which moves the slider up.

The pressure from your foot, via the wedge, is acting against resistance from a spring pushing the opposite direction. As the potentiometer moves, the resistance goes down causing the machine to go faster.

I suspected the potentiometer because it was all gunked up.  It's heavily greased to keep it moving smoothly and, since the pedal sits on the floor, the grease had picked up a lot of carpet fibers and other stuff.

The two contacts for the potentiometer are at the top end. An ohm meter showed it was OK; it's an open circuit until the slider hits about the halfway point, then the resistance starts high (I didn't write down how high) and drops down to a short as the slider reaches the far end.

The spring arm pushes on the
slider and holds down the lever switch.
The pedal doesn't rely on the potentiometer to turn the machine on and off.  Right next to the potentiometer there's a lever switch with an arch at the end of the lever.

The end of the spring that pushes against the potentiometer slider crosses over the switch lever.  When the pedal is in the "off" position, the spring wire pushes down on the lever (at the bump) and keeps the switch off.

As you push on the pedal, the wire from the spring moves off the bump, the lever pops up and the switch turns the serger on.

It doesn't immediately start serging because the potentiometer is still too far down to let any current through.

The Problem
Turns out that switch was broken.  The same ohm meter proved that.
It wasn't the contacts, they were soldered on securely.  The switch was just bad.

The desoldering tool sucks
away the molten solder.
I melted the solder with an iron, then sucked it off with a handy desoldering tool.

You cock it by pushing down a plunger through a cylinder.  When you press a button to release the plunger, it springs up, creating a suction in the cylinder and sucking the molten solder in through a nozzle.

The Fix
I found a reasonable replacement for the switch at Radio Shack.  It's a SPDT (single pole, double throw) Submini Lever Switch.  "Reasonable replacement" was the best I could do on a Sunday.

The replacement switch
has a shorter lever.
The replacement switch had two salient differences from the original: the contacts were perpendicular to the switch and the lever was both shorter and lacked the bump.

With a pair of longnose pliers I twisted the contacts so they would fit through the circuit board.  They bent easily enough and didn't break.  There was just enough contact after the twist to fit through the board.
Old lever glued to new lever.

It soldered in just fine.

I couldn't figure out a decent way to get the new lever to work, so I cut the old lever off the broken switch and glued it on top of the new lever.  It worked fine.

The Putting-It-Back-Together Glitch
Yeah, there's one of those, but it's not bad.

The ramp on the top of the pedal that moves the slider is like a hill; it goes up, peaks, then goes down.  To work right, the roller on the slider has to be on the back side of the ramp.  If you just lay the top of the pedal over the bottom, the roller lines up on the wrong side of the ramp.

All you have to do is push the slider forward with a screwdriver while you align the top of the pedal over the bottom.  Once they're kind of together, you might peek inside with a flashlight to make sure.  Then you just pry the protrusions back into the holes and pray that it all holds together long enough for you to take credit for fixing it.