Todd Wolfson

Software Engineer

April 07, 2018

I've been slowly picking up electronics over the past year. At this year's Burning Man, 3 out of 5 EL wires broke on me. This time, instead of e-cycling them, I decided to use it as a learning opportunity.

If you've never done electronics before, SparkFun is a great resource. This video got me into it by finally understanding how to debug (like me learning about Firebug for the first time):

2017/10/11

The first step was isolating the problem. The EL wire I have is 1 circuit + battery holder and 1 wire which clips in.

EL wire setup

I took 1 broken blue set and 1 working red set and tried different mix and match combinations:

  • Red wire + red circuit - WORKS
  • Blue wire + red circuit - WORKS
  • Red wire + blue circuit - FAILURE
  • Blue wire + blue circuit - FAILURE

That made it definitive that something in the blue circuit/batteries was broken. It was possible it was the batteries so I double checked:

  • Blue circuit + blue batteries - FAILURE
  • Red circuit + blue batteries - WORKS

Okay, now it's definitely the circuit


Next, I wanted to keep on isolating the problem. I opened up both of the circuits and visually inspected them

There were no visually broken capacitors so maybe it was connectivity issue

I connected a multimeter to the ground terminal of where the circuit would be. Then poked around with the positive terminal on the rest of the board

Everything seemed connected on both boards

I couldn't figure out what was wrong

Then, I decided to connect to the button's solder points

Annotated circuit

Ah ha! It looked like the red circuit's button worked in any direction whereas blue's button only activated when pushed in a very specific corner

I put the blue circuit back together and pushed the blue button in its specific corner and it worked!

So the problem was most likely the broken button

I had only soldered once before this point and that was for jumper headers so I was taking things slow and stopped for the night

2017/10/22

The idea I had to verify the button truly was the problem was to replace it with wires as a proof of concept

As a result, I:

  • Verified wires would fit through button's casing hole
  • Desoldered the button
  • Soldered in wires
  • Reconstructured the chassis (so I could add batteries/power -- I don't have a power supply)
  • Touched wires together

It worked!!

For double sanity, I hooked up the button to the multimeter and confirmed it only worked in the specific corner

Some time between 2017/10/22 and 2017/12/20

Now that the issue was identified, I decided to order replacement buttons

However, clearly this wasn't going to future proof the device from it breaking again

At the time, I thought the issue was the buttons being too tall so my solution was to buy a shorter button, hot glue it to the top of the case, and run wires to the PCB's holes

I'm still a little doubtful that that was the problem (e.g. could have been dust from Burning Man getting into the button's internal circuits)

So I might wind up taking even more precautions in the future (e.g. taping over the button's hole)

Anyway, at this point I bought momentary buttons to get started

2017/12/20

The buttons had arrived and I did a simple placement test to verify it would fit

2017/12/31

I hot glued a button to the top of the case

I verified its connectivity afterwards (e.g. heat could damage circuit)

Don't worry, I still went out on NYE ;)

2018/02/14

Another delay, this one was caused by wanting to buy a fume extractor and personal life

I also purchased a new soldering iron for better temperature control (Hakko Fx888-D is wonderful). My old solder was a Weller with no knobs, only a plug for the wall outlet

After they arrived, I desoldered the EL test wires

2018/02/19

The following is directly from my notes:

  • Delay due to purchasing wire strippers and solid core wire (24 AWG from hardware store, couldn't find 22 AWG =(
  • Learned to "wet" wires before soldering
  • Soldered wire to button
  • Ran wires through holes
  • Tried to solder again but the traces weren't accessible (soo much wicked off or burned over)
    • I now know how to deal with this (see Adafruit troubleshooting later on)
  • Dropped temp to 650
  • Soldered into alternative holes but those weren't connected to the proper traces
  • Tried another board
  • Desoldered button partially as well as snipped ends as well as broke physically
    • I was trying to avoid ruining traces. Unfortunately, I still did
  • Soldered 1 wire fine but trouble with other one
    • Solder was getting onto wire but refusing to go on pad so it would stay on wire or iron
  • Got frustrated multiple times
  • Finally read through https://learn.adafruit.com/adafruit-guide-excellent-soldering/common-problems
  • First tried isopropyl alcohol then soldering again
  • No luck
  • Got frustrated and read some more
  • Tried scraping with knife and saw copper lead exposed as mentioned towards bottom of article
  • Exposed enough copper lead and soldered to it
  • Closed up case, inserted batteries, and pressed button
  • LED was displaced so could barely see it
  • Connected to EL wire
  • IT FUCKING WORKS!!

EL wire working

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