Archive for February 6th, 2009
Not that anybody pays attention to these things, but NOAA’s N-Prime earth observatory had a successful launch today.
There’s a bit of backstory to this bird: Lockheed-Martin manged to drop the satellite during the final phase of its assembly, causing all manner of damage. Basically, they forgot to bolt the booster adapter down before trying to tilt the satellite over.
It seems L-M ate the rebuild costs, which was a nice gesture on their part.
I wrote about the event in my Dr Dobb’s Journal column some years back, in the context of how we do error checking in our projects. Bottom line: no matter how good you think your development process might be, alas, you’ll always miss something. The trick is to miss only small problems, not project-killers.
Now, if only the bird works correctly…
This type of switch is a nice alternative to the ordinary pin-header option jumpers: pull the white plunger up to open the switch, push it down to close. Nothing to lose or (worse) drop into the machinery.
Being that sort of bear, I test most components, particularly surface-mount parts, before soldering them onto the board. Switches, however… well, what could go wrong?
Unfortunately, both of these switches were defective.
The gutted switch at the top of the pictures stuck open after I soldered it in place: pushing the plunger down didn’t do anything at all. Leaning rather hard on it didn’t get its attention, so I unsoldered and tore it apart. The parts looked OK: no obvious corrosion or deformity.
I tested the second switch, found it worked perfectly, and soldered it in place, whereupon it failed just like the first: stuck open.
Perhaps the soldering iron’s heat (immeasurably) reshaped the plastic or (invisibly) oxidized the contact point? Maybe the design is close enough to not working that installing it pushes the tolerances over the edge? I’ll never know.
These were surplus parts, so there’s no recourse, but I’m pretty sure they’d misbehave the same way if I’d paid full retail for them. If you see any inside your widgets, this may be why you can’t select an option… or why the widget suddenly enters a mysterious new mode.
I tossed the rest of my supply in the trash.