Punked Eggtimer Quantum

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BDB

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I really like Eggtimer products. I've enjoyed building a few of them so far, but I think I just screwed my first one up. I have two Quantums. I just completed the build for the second one a couple weeks ago, and, at the time, it powered up and I was able to connect to it via wifi. I just set down to program it tonight, and it won't even start up. I know the issue isn't my LiPo because my other Quantum works just fine. I looked at every joint and they look ok (at least my my crappy soldering standards). The only joint that I suspect could be problematic is on the backside of the unit (pictured below). It's nearly impossible to keep the two solder joints separate, so I did my best. Honestly, the soldering job on my other unit looks a little worse.

Has anyone else experienced anything like this?
 

Tonimus

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Deleted- double post
 
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Tonimus

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That 4700 ohm resistor does look like it is shunting those other two connections. I would recommend desoldering the resistor, probably with a vacuum. Then use some desoldering wick to clean up the pads and the neighboring offending pads. Then try again. I've had good luck with soldering paste with close proximity connections.

I would also reflow all of the circled connections. The single connections on the left look especially suspect.

ImageUploadedByRocketry Forum1502337881.959439.jpg
 

OverTheTop

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Hi BDB. Some of the joints look like they have not wet properly with solder (although it is hard to tell in photographs sometimes). Were you perhaps using a very small soldering iron, or rushing the joints?

Make sure you inspect all your soldering with at least a x10 magnification after you have done it. If you have cut any legs off with sidecutters, make sure you inspect the joint after you have cut the legs.

Hope you get it going.
 

BDB

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You guys are right that this build seemed wonky at times. The solder didn't seem to flow like it did on my other quantum. And I may have been rushing some if the joints.

I just thought I'd ask you guys if you'd seen anything like this before. I'm happy to chalk this one up to a learning experience. I'm a chemist by day, so this EE stuff is new to me. But I'm having fun figuring it out.
 
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snrkl

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FWIW: I used to have trouble like this soldering - I found a neat video from adafriut that was very helpful: [video=youtube;QKbJxytERvg]https://www.youtube.com/watch?v=QKbJxytERvg[/video]

The changes I ended up made to my technique were simple and I haven't had an issue since...
 

ttabbal

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Since it's a power problem, I would check the power supply areas. The bridge rectifier, the regulator and capacitors in particular. Ensure that you get 3.3v out of the regulator. Don't forget the input connections as well.
 

cerving

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That 4700 ohm resistor does look like it is shunting those other two connections. I would recommend desoldering the resistor, probably with a vacuum. Then use some desoldering wick to clean up the pads and the neighboring offending pads. Then try again. I've had good luck with soldering paste with close proximity connections.

I would also reflow all of the circled connections. The single connections on the left look especially suspect.

View attachment 325465
DO NOT cut that trace or remove that resistor. You will not get any continuity readings if you do. That resistor shunts the source & drain of the FET so that only a little bit of current can flow to the igniter for continuity checking. Right before firing, the FET is turned on to allow a low-resistance path to ground. This is part of the dual-ended deployment circuitry on the Quantum... there is a transistor on both ends of the igniter so there is no direct connection between either leg of the battery and the igniter (unlike other altimeters which always have one leg of the igniter "hot").
 

cerving

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That 4700 ohm resistor does look like it is shunting those other two connections. I would recommend desoldering the resistor, probably with a vacuum. Then use some desoldering wick to clean up the pads and the neighboring offending pads. Then try again. I've had good luck with soldering paste with close proximity connections.

I would also reflow all of the circled connections. The single connections on the left look especially suspect.

View attachment 325465
The Adafruit video is very good. The most important things are that you get the right temperature and tip size, and that you keep the tip clean. Use a cleaning/tinning block and a mesh "sponge".

FYI, DO NOT cut that trace or remove that 472 resistor (except to clean up the solder, of course). I've had a few people try to "fix" their problems by doing this. You will not get any continuity readings if you do. That resistor shunts the source & drain of the FET so that only a little bit of current can flow to the igniter for continuity checking. Right before firing, the FET is turned on to allow a low-resistance path to ground. This is part of the dual-ended deployment circuitry unique to the Quantum... there is a transistor on both ends of the igniter so there is no direct connection between either leg of the battery and the igniter (unlike other altimeters which always have one leg of the igniter "hot").
 

cerving

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Yes, I figured that out after I re-read your post. I was just warning anyone else reading it... I HAVE seen people cutting that trace.
 
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