Be super extra careful to avoid getting any tiny wire strands or solder balls down inside the sleeve! Also watch out for solder bridges between the pads.
There may be little bits of rubber stuck here and there. Peel them away with tweezers, or scrape them with the iron if they’re on the solder pads.
NeoPixel strips are all manufactured in half-meter lengths. These are joined at the factory to produce a complete reel. If you look along the strip, you can clearly see where the sections are joined…there are solder connections there.
Measure 2 meters down the strip. Or simply count four half-meter sections.
Normally you have to heat the three pads and gently twist the strip away (it may take several passes). Or if you’re lucky, you have an iron that they make these extra-wide tips for.
As with the end of the strip, watch out for solder balls and bridged pads.
Later steps will be easier and less error-prone if all of the strips (both the 2m and 1m varieties) are laid out flat, all oriented the same way. Don’t leave them in a heap of disarray.
Working with 10 reels of NeoPixels, there’s now 20 two-meter strips and 10 one-meter strips. The latter will be reconnected into 5 two-meter strips, for 25 two-meter strips total. 24 will be assembled into the curtain, one is left over as a spare (for future repairs). With better planning I’d have allowed for a few additional spares!
A straightedge is used as an alignment guide; this and the LED strip are taped down to the work surface.
Make sure you’re connecting DOUT to DIN. Don’t join strips back-to-back!
These strips are going to see a lot of abuse, and the solder connections better be bulletproof! If you’re having trouble successfully re-joining strips, you may need to remove the old solder from the pads (using solder wick) and start fresh. Old solder gets weird and sticky when all the flux has boiled away.
We’ll now add JST plugs to each strip. Wait…didn’t we just remove a bunch of JST plugs?
Using plugs (rather than hard-wiring the strips) makes maintenance much easier, if any strips need replacing later.
IMPORTANT: Set the female (socket) receptacles aside for later, use male (pin) plugs on the strips. This is the opposite of the factory connectors, but it’s safer (sticky-outy things on the power supply side is a bad idea).
JST plugs feature a polarity “key” so they don’t plug in backwards. Doesn’t matter which orientation you choose, just make sure every plug/strip is aligned the same way!
Not too much, not too little, and not “balled up” on the surface. It may work best to wick off any old solder and apply fresh.
And you know the drill by now: don’t let any solder bits get down inside the sleeve.
- Are all the JST plugs oriented the same way on every strip? With the “key” facing either up or down? Doesn’t matter which way, just be consistent.
- Did you connect to the DIN end?
- Use a multimeter to test for electrical shorts: GND to DIN, DIN to +5V, and GND to +5V.
- For the joined strips, confirm DOUT connects to DIN; arrows should point the same way down the whole strip.
Return to the Arduino code that was used for testing reels, and make one small change near the top:
#define N_LEDS 60 // 2 meter strip @ 30 LEDs/m
#define N_LEDS 60 // 2 meter strip @ 30 LEDs/m
Take one of the mating JST receptacles (female socket) and strip a little extra insulation from the wires. Plug it into one of the strips and trace the wires so you know exactly which is +5V, GND and DIN. Double check, then maybe even stick labels on them.
Connect the wires to the corresponding points on the Arduino: 5V, GND and pin 6. If possible, route DIN through a static-protection circuit as shown on the prior page.
Re-connect the USB cable. You should get the LED “chase” again, red, green and blue. Let it run for a couple minutes as you examine the entire length of the strip. If everything checks out, unplug USB first, then the JST connector, then reverse these steps as you connect the next strip for testing (we’re avoiding connecting the strips to a live circuit).
Troubleshooting is about the same as for reels. If there’s a problem, stop immediately and refer to the checklists on the prior page, and also look for the following:
- Confirm that 5V, GND and DIN are properly routed from the strip, through the JST connectors, to the Arduino.
- Confirm you’ve soldered the plug to the DIN end.
- Confirm all the JST plugs are oriented the same way. You can have all the “keys” on the NeoPixel side of the strip, or all on the back, but not a mix of the two.
- For joined strips, confirm you’ve soldered them DOUT to DIN (arrows all pointing the same way), not back-to-back.
Do not continue until every strip has been tested. Going forward, all those solder connections become inaccessible…if something was mis-wired, it might not be salvageable after this.
Set aside all the full 2m strips. This next part applies only to the joined (2X 1m) strips.
Lets fix those gaps in the sleeve, where the two pieces meet…
Wriggle the sleeves so the ends butt together close to the solder connection. You may need to hold the end of the strip with pliers and “inchworm” the sleeve down a few millimeters over several passes.
Squeeze some hot-melt glue or Permatex 66B under both sleeves, top and bottom (tested both…hot glue is cleaner). Re-butt them, slide the tubing over the gap and shrink it using a heat gun.
You really need to use a heat gun for this. Flame does not work well on large heat-shrink, and may be unsafe for certain glues!