Soldering Fairies

Since I started putting up a Christmas tree at home each year, I always have some sort of decoration lights at my home. LED strings are cheap and very bright and work very well for Diwali lighting too. I got a new string recently – plain yellow and without any blinking pattern - to add to the red and green ones I had already. It seems these don't sell well as mostly people are more into multi-colored and blinking lights. The one I got was very cheaply made - it cost just Rs.30 for a length of 7 meter.  A slight hasty tug or two made many wires break at the LED contacts and I was left with a "dull" string. Of course no one would repair it, the cost of repairing was almost equal to buying a new string, so I was advised to chuck this and buy a new one; which I did, again after much hunting. The old string though wasn't beyond hope and it seemed like such a waste to trash a perfectly good thing.

So the following ensued:

Ingredients:

1. A soldering gun - 25W

2. A solder wire - gauge 20

3. A Swiss knife

4. An old sponge

5. A magnifying glass

6. A crystal bowl - for the gun stand
7. Youtube

The means.

Recipe:

1. Put on some good music. My chosen band was Kakkmaddafakka.

2. Remove the insulation from the LED contacts and expose them properly. Do same for the ends of the connecting wires so that the wire is exposed. An electrical wire-cutter is used but I just settled for the strong scissor in my wonderful Swiss knife. For the wires, make gentle cuts on the plastic sheath, being careful not to cut through the wire inside, and then pinch and pull off the plastic with your fingers.[To the naked eye, the LED contacts were of the same length and I couldn't spot the flat edge of the kathode inside the LED, so I spent some time examining the them carefully under the magnifying glass, to figure out which was the positive and which was the negative. Irritatingly enough, both the contacts were exactly the same. So I just decided to trust my luck and solder them as I thought. I still do not know why these didn't have the kathode/anode differentiation. Do serial light LEDs work if connected any which way ?]

3. Dampen the sponge. Don't go overboard and make it soaking wet.

4. Plug in the gun and place it on the stand. [I used a glass bowl for this as I didn't get a stand with my gun.] Let it heat for about 2 minutes.

5. To see if it is ready to work with, touch the tip of the solder wire on the tip of the gun. It should melt and form a tiny, shiny blob on the gun tip. This is "tinning" the gun tip.

6. The solder blob on the tip can be wiped off easily with the damp sponge. Try it. Re-tin the tip.

7. Now place the two parts to be joined together - the led contact and the connecting wire end - and keep this on the tinned gun tip. Now from the other side, touch the solder wire slightly to the join and melt it. The join is totally covered by the melted solder now (From the solder on the gun tip, on one side, and the solder wire, from the other).Remove the solder wire. Remove the gun. A small blob of solder should remain on the join and it will immediately solidify in place, thereby making the join as desired.

8. If the join breaks or the solder doesn't stick, clean off the contacts and the wire, clean the gun tip and try the same process again. Try to "swipe off" the gun when removing so that at least some solder sticks and remains on the join. 

9. If there are many breaks in the string to be fixed, fix them all as you cannot test until all of them are joined properly to form the complete circuit.

10. Clean the gun tip and unplug the gun. Plug in the string and make sure it lights up. If not, re-check the string for any breaks.

11. Secure the fixed joins by wrapping some insulating tape strongly around the contacts. I think it’s a good idea to separate the two contacts by placing a small piece of rubber or plastic between them so they don't touch each other, and then wrap the tape around them tightly. Either way is fine. I forgot to buy this tape so I used normal cello-tape.

12. Your LED string is done and ready to serve [you].

It's alive!

PS:

> Soldering isn't that risky.  Just be careful not to touch the hot gun and not to drop the molten solder on yourself.

> The Internet has instructions to do almost anything! Thanks to the "Internet soldering teachers".

> A kind friend assured me that this plan of mine to solder for first time without any help or supervision was not a stupid idea [unlike scores of other ideas I have every day]. He will get a cool Mickey Mouse painting in return for his help.

> The shorter contact out of the LED is the kathode, the negative end. The longer one is the positive end, the anode. [HOW could I forget this?]

> They are called "serial" lights as the LED lights are all connected in serial. So if just one blows, it breaks the circuit and the whole string refuses to light up.

> Soldering iron does burn like hell if you touch it. Not just the tip but the whole metal part. Temperature is around 400°C I think.

> The solder can have some lead, so make sure you don't inhale the poisonous fumes.

> Soldering is actually pronounced as "soddering" in USA! Who knew? Stupid silent letters. L, in this case.

> Yellow fairies always beat the others in prettiness!

The end.