Sunday, April 17, 2011

"No User Serviceable Parts Inside" Means Nothing To Me

So two guys pass each other in midair. The guy going down says "Hey, do you know anything about parachutes?" The guy going up says "No. Do you know anything about gas stoves?"

I was reminded of this slightly paraphrased joke during this weekend's hack. Meet my nemesis.
I Hate You
This is the control panel on our gas stove.  Lately it had decided to start fading out on us.  Pressing on the left side of the panel would bring the display back, but only temporarily.  Classic loose connection type of problem.  Since this was happening more frequently, and since I depend on this display's clock to keep an eye on how long I brush my teeth in the morning, I decided it was high time to tear my gas stove apart.

And tear it apart I did.  The burners came off first.  It takes about an 1/8th of a turn, but they basically just spin right off (once you get past the years of burned on crud sealing the burner to the stovetop, of course)  I left the wires for the igniters attached to the burners and just laid them on the stovetop.  Taking the burners off uncovered six screws that needed removing.  I took those out and then was able to slide the stovetop forward and then up to detach it from the rest of the appliance.  Six more screws held the front panel of the stove on, and they were easy to get at once the top was off.  The front cover on which the control panel was screwed to came off easily after removing the four knobs controlling the gas flow.

There are three connectors at the back of the control panel: two on the left and one on the right.  I pulled those off and and then took off the four screws holding the control panel to the front panel.  The control panel was now freed from its confines.

It turns out the control panel is actually a set of two circuit boards that were joined electrically by a couple flexible connectors, and mechanically by a couple of plastic clips that looked like they'd surely break if I tried to pry them open.  Hmmmm.....

Then I gave the control panel a shake and heard a rattle.  Not good:circuit boards don't rattle.  The rattle was coming from behind the keypad.  I pried away the six plastic clips holding the control panel to the keypad and was rewarded with a small piece of plastic dropping out.  I saw right away that this piece of plastic transferred a press on the up arrow of the keypad to a switch on the control board below.  Hmmmmm...

If I couldn't fix this, I was screwed.  So I first tried to glue the piece on with a bit of Krazy Glue.  They call it Krazy Glue because you must be batshit-crazy if you think that stuff will work on anything.  It did nothing besides make a mess and give me a headache.  Time to turn to Old Faithful.
Love This Stuff
Of course it wasn't quite this easy.  It seems that some of the epoxy had mixed together near the tip of the applicator and it was almost impossible to get the cap off.  But I prevailed.  I mixed up a bit of epoxy and put it on the plastic thingie, let it dry a bit, and put the keypad back on.  Seemed to work.  So far, so good.  Back to the problem at hand.

Like I mentioned, I didn't want to take a chance on breaking the plastic clips holding the two circuit boards together.  I figured the intermittent operation was just a poor contact on one of the three connectors at the back of the control panel anyway.  So I pushed them on and off a few times to clear the connectors of any crap, and pushed the pins off center a bit to ensure they'd make better contact when the connector was put back on.  I applied power back to the stove, wiggled the connectors, and everything looked solid.  Even my up arrow was working (thanks, LePage).  I put the stove back together and everything worked great.

For a couple hours.  FML.

So this morning, I took the damn thing apart again.  This time I'd have to dive into the circuit board sandwich held together by those plastic clips.  I held my breath, pryed the first one a bit, and it came off!  Without breaking in half!  Miracles can happen!  What about the second clip?  It came off cleanly too!  Time to buy a lottery ticket: I am on a freakin' roll here!

To make a long story less long, I saw the cracks around the solder joint on several connector pins within seconds of prying the two circuit boards apart.  It was just a few minutes work to rework these and the rest of the connector pins.  I put everything back together and so far, so good: I have been basking in the stove's green vacuum flourescent display for over ten hours now.  And I suspect it will be glowing just as brightly as I brush my teeth under its watchful eye tomorrow morning (I know you are having trouble wrapping your head around all this.  It might have helped to explain that I brush my teeth for ten minutes in the morning at the dining room table while surfing around from my laptop.  Don't you judge me.)

So what can we learn from all of this?
  1. Taking something apart goes quicker the second time around.
  2. You will always have to take something apart a second time because you won't find what was really wrong the first time.
  3. In general, I am cursed.  But sometimes I get lucky.
On the bright side, my spare time is pretty cheap.  Had I failed to find the problem, I'd have had to have gone to someplace like this and be out of pocket for $168.40.  Yay for ignoring those warning labels.

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