The Eggtimer Apogee - A Very Simple Apogee-Deployment Altimeter

[cerving]

Any chance that you could have shorted the screw switch head against something else on the board when you were trying to turn it on? That's a possibility with the earlier A7 version of the Apogee, we put out an advisory for it... we recommend that you cover the transistor terminals with epoxy after testing it. With the newer A9 version it's much harder to do that... but you can still do it if you use a small flat-bladed screwdriver and contact just the right spot. We recommend that you use a #2 Phillips screwdriver to prevent this (that's what size the screw wants anyway). If you have an Easy Mount, there's a guard around the screw... it's impossible to short the screw head to the board.

 

[boatgeek]

Any chance that you could have shorted the screw switch head against something else on the board when you were trying to turn it on? That's a possibility with the earlier A7 version of the Apogee, we put out an advisory for it... we recommend that you cover the transistor terminals with epoxy after testing it. With the newer A9 version it's much harder to do that... but you can still do it if you use a small flat-bladed screwdriver and contact just the right spot. We recommend that you use a #2 Phillips screwdriver to prevent this (that's what size the screw wants anyway). If you have an Easy Mount, there's a guard around the screw... it's impossible to short the screw head to the board.

I saw the advisory, and I have the A9 board. I've only used #1 or #2 Philips screwdrivers on it. I don't *think* I shorted it while turning it on, but it's possible. What was weird is that the E-match fired while the altimeter was turned off, not during altimeter startup. If I had to guess, I'd say that there was residual power left in the capacitor that somehow made it to the E-match.

 

[cerving]

There is no firing capacitor on the Apogee (or any other Eggtimer altimeter). I'll see if I can recreate this sequence.

 

[boatgeek]

There is no firing capacitor on the Apogee (or any other Eggtimer altimeter). I'll see if I can recreate this sequence.

OK, sounds good. I'll try to replicate it with a voltmeter to see if there's residual power after the screw switch is off.

 

[boatgeek]

Some very rudimentary testing:

Apogee on, no continuity: ~3.8V across the output terminals (assume this is the voltage for checking continuity and resistors would keep current from getting too high)
Apogee off immediately afterwards: ~1V across the output terminals, falling fairly quickly
I couldn't replicate firing the E-match after turning the unit on and off
I didn't have easy tools to check amperage through the outputs in the tests above

I'm guessing that I accidentally shorted something on startup/shutdown.