I Can't Sleep When Things Are Broken, a Dishwasher's StorySun 08 September 2013 by Cory Cross
One night, about a year ago, I started my dishwasher before going to bed. It has a few steps it goes through when you turn it on: pump out the old water, let frsh water in, then once the water is high enough, turn on the recirculating pump and start washing. So I hit start and lay down in bed. It's pretty noisy, but it's white noise. About one minute after laying down, I'm almost unconscious when I'm right back alert. No sound. Hmm, maybe I fell asleep and didn't notice. I check the dishwasher: everything's dirty. Okay, put more detergent in and start again; who knows, maybe I imagined the whole thing. I go back to bed, but listen this time. Silence again. Why?
This escalates to me having the dishwasher torn apart, parts and tools strewn about the kitchen. Screwdrivers, multimeter, and jumper wires at my disposal. I reverse-engineer the wash cycle, using the manual and the parts at hand to reason out what it is supposed to do. Water is everywhere while I'm wrapped around and probing 120V wires -- at least it's plugged into a GFCI outlet.
I eventually figure out the motor is supposed to be pumping the hot water -- crap, motors are expensive. It has a funny power arrangement, 3 power wires (ignoring starter/run stuff). One is neutral, of course, but the other two run to the control board. I jab a jumper wire and connect both to 120V hot. It makes horrible noise! That's better than silence. A few minutes later and I reason out you apply power to one wire when you want to discharge water to the sink and the other when you want to pump it into the sprayer. And the motor works perfectly when I do that! Now we're down to the control board, fortunately my expertise :).
So I'm not measuring any voltage coming out of the control board, so there are two choices: either the logic isn't requesting voltage (probably requiring replacement) or the output stage is broken, a transistor or relay most likely. I follow the traces back from the motor output to the relay. I figure out which traces control the relay, then I plug everything back in and hit start on the dishwasher, while I probe the signals. When it gets to the proper stage, 12V appears on the coil of the relay, but nothing on its output. Woohoo! Just a bad relay. Digikey even has a part. I add it to my Digikey parts list and can sleep, knowing just what needs to be done. (I could have used a spare of a different sort, but I was tired enough to sleep by that point).
But now that I've learned how all the clever little mechanisms work, it seemed a shame to hide them back under the sheet steel. So I resolved to cut out the side and add a window. I finally have.
The curves not so good
When I examined the curves of the boat as I began assembling it, I realized something was amiss. The front curved inward far too tightly. When I drew the lines on paper I realized I had done it so tightly the side would have been concave!
So real designers use ...read more
Built forms, mounted aft hull
When building a plywood stitch-and-glue boat, you don't need to build the boat on the traditional forms and strongback because the shape of the panels fully constrains the boat. However, since I have created my own plans, I don't have the shape of my panels. They could theoretically ...read more
Lines drawn, bulkheads cut
I got impatient waiting for the Piccup Pram plans to arrive, so Saturday I went down to the library and read 20-odd issues of Boat Design Quarterly. BDQ has a collection of about 6 plans varying from "study plans" to full dimensions for different boats in each issue. A "study ...read more
Change in plans
Been scraping off the old epoxy and finally put new fillets in. But as I've been planning the mast and sail plan, I didn't like the designs that I came up with. The amas (side floats) would be plenty strong, but I don't know if the center ...read more
Ruh-roh, screwed up the epoxy mix
I went to add more fillets today and noticed yesterday's were still squishy. Ruh-roh. I haven't used this epoxy before and thought maybe the cool temperature just makes it take a long time (though unlikely). So I carefully made up another batch, added more fillets, and it set ...read more
They aren't the prettiest fillets ever
Okay, next time I'm going to start with the fillets at the bottom of the boat. Because when reaching down to the bottom I wiped my arm across the ones at the top. Yuck!
They aren't pretty, but they're hopefully functional.read more
My airplane's last flight
As a kid I always wanted to have an r/c airplane. My dad and I bought one but never finished it.
We finally flew one a couple weeks ago. Every time the plane landed though, it broke a little more. We had a few layers of duck tape holding ...read more
Stitching the bottom in
Complex curves are hard.
As the bow curves upward, the bottom pieces slope upward (downward in these pictures since it is upside-down) in a complex 3-dimensional curve. I started trimming the front to match the curve, and I couldn't get them to bend or line up worth a damn ...read more
First Bow's Rear Bulkhead
So I glued up the reinforcing pieces of 3/4" (so-called 1") thick, 1.7" inch wide pieces of pine to the inside of the rear bulkhead. There'll be 1/2" holes through this where I'll bolt 1/2" SS bolts through to lock the hulls together.
The ...read more