Let the new guy crash once. Eggtimer lessons and success!

Discussion in 'Rocketry Electronics and Software' started by TimothyG, Dec 6, 2018.

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  1. Dec 6, 2018 #1

    TimothyG

    TimothyG

    TimothyG

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    During the holiday sale I managed to get our school to help us arrange a large group purchase of eggtimer products. Thankfully the electronics store lady decided I was polite enough to help us make this happen without having to go up the chain of bureaucracy. If you happen to see this thank you H. To start off I screwed up so badly on my LCD receiver that I had to spend two hours going over my board with a multi-meter checking for continuity of the board structure after burning off multiple pads using improper settings on the soldering iron.

    I used to be a machinist and one thing I learned is whenever you get a new guy in the shop you should keep them on cheap simple products until they crash once. Either the machinist will be overly confident or overly nervous at their new job and needs a good scare to settle the nerves. I'm the overly nervous type myself and so it was with my Eggtimer products.

    I started off with the wifi switch for a practice run and I didn't read as much into the directions as I probably should have. I lifted one pad during desoldering with a wick but the wifi switch managed to keep working despite my screw up. Unfortunately this led me to believe I was ready to tackle a bigger project in my receiver. What I failed to pick up on with the wifi switch was that I had been running the soldering iron at 450 f after reading that this was low temp solder thinking it was the safer option. While soldering I ended up with many cold joints on anything with any size to it, as a result of this improper guesstimate. While soldering the 50V 10uf (micro not u) capacitor I managed to cold joint the inner pad that is on the bottom going through the board to the input side of the capacitor. In trying to get this joint fixed I cranked up the iron to 550 and kept trying to make things work. This resulted in me loosing track of what I was doing and cooking the pad till it came off with the solder blob that resulted from my screwing up.

    The fix at this point was to consider ordering new board and components from Eggtimer to replace the screwed up assembly. But I made the ingenious decision of .... Asking for help!!! Another engineering student working on his senior design project was willing to look over my work and let me watch him fix a few things. During this process he noted I was running the iron way to cold being "bashful" with the temp. He cranked it back up to 680 f and fixed the majority of my cold joints. After this happened he showed me how to use the multi-meter to check all my connections after soldering them and some methods for getting around my screw ups. Thanks to him I was able to determine that all my pulled pads were present on the side of a contact that allowed me to use the bottom of the board to get around these screw ups. I managed to source a 50V 10uf electrolytic capacitor from the ECE store and mount it on bottom so I had two good pads still and fix all my other cold joints.

    The payoff was tonight I got everything tested and 100% function on everything so far. Plus now I got my confidence back and soldering takes 1/4 the time it was taking me

    So far I've completed two wifi modules one with no flaws. A tracker a receiver and gps module and half a proton. (Although secretly I think I may have screwed up on the proton but won't know till I test it.)
    chip2.jpg chip1.jpg chip3.jpg chip4.jpg chip5.jpg .
     
  2. Dec 6, 2018 #2

    SteveThatcher

    SteveThatcher

    SteveThatcher

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    glad you found someone who could help out. For the EggTimer boards (and in general), 680 degrees is just fine. I do all of my work at 650 for printed circuit boards and crank it up to 750 when I have to do larger parts that have more thermal mass like heavier gauge wire (18, 16, and on down). One thing to always remember is that a solder connection should always be shiny. When you attach wires to a board, you can create a bad solder joint just by moving the wire before the solder solidifies by cooling down.
     
  3. Dec 6, 2018 #3

    Charles_McG

    Charles_McG

    Charles_McG

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    I also started off by listening to (but not understanding) all the points about low temp solder and using low wattage irons - and turned the temp down (when I finally bought a controlled iron).

    Eventually, I noticed a recommended temperature in one set or another of Cris' instructions. I've forgotten which. Much higher than I was using, and it works much better.

    As a chemist, I should have remembered that heat flow is proportional to delta Temp. Combine that with a fine tip, and there just wasn't enough heat transfer.
     
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