Electronics Problem!!

[franz bolo]

I'm making an Alien tracker thing for my son's Halloween costume.

I bought a couple kists and tried to solder them today. I never soldered and only have a very basic knowledge of electronics.

Anyway, I have a few problems. Here's a video I just made. Notice it skips over numbers 5-33 at the top. It also reverses and does something odd between 1-31 when it slows down.

http://www.youtube.com/watch?v=-tVbB_3ZPHs

Here are some pics of the soldering.
http://i191.photobucket.com/albums/z60/j6studios/wiring.jpg

Any ideas?? I had solder between 2 LED's and tried to fixed it. It didn't fix the problem.

Thanks

FB

 

[NakedMoleRat]

1. Check you solder points and make certain that nothing is touching each other, or crossing onto another line.

 

[CessnaDriver]

Make sure the LEDs are not in backwards. You will have to look at the insides of the LED to see the difference in the leads, magnifying glass helps. Compare to ones that work.

Reflow the suspect connections, though they look good from what I can see, but perhaps what is called a cold solder joint is present.

Replace a bad LED with a known good one as a test.

 

[Zombie Killer]

Have you checked to make sure the LEDs are in the right orientation? ie + and -. Also Leds are easily damaged with too much heat. You might have fried them.

Edit Cessna beat me to it.

 

[Mr.Engineer]

Apart from checking the polarities of the LEDs, And without the picture of the upper part of the circuit board, I can only look at the soldering.

First thing first, the soldering skills must be improved. Take a spare/junk circuit board and practice on it, and you will soon know the difference between heat transfer when soldering and desoldering components. And don't worry about the burnt fingers. It'll heal. Well, it should.

This is because I see a lot of blobs forming on the LED legs and the track pads. If you look at the lower right, you can see one that was not soldered well. In this case, it might create a bad electrical joint.

The idea is to touch the tip of the solder to the pad, and then let the solder melt from the tip to flow onto it. Personally, I just touch the pad and the LED legs together and push a certain amount of solder to let it flow. If everything works well, you would have a mini mountain. Oh, the time limit (for me) per solder is about 5 seconds. Too long and it would kill the component or tracks.

From the picture, the circuit board (PCB) is the cheaper SRBP (something Resin Bonded Paper, if I am not mistaken) where the copper track comes off easily as compared to fibreglass version.

 

[tim]

^ Agree with all of the above. In the OP's photo, some of the solder blobs have a hazy gray color, which is a hallmark of a cold solder joint that will be prone to failure. Check and reflow as appropriate.

Make sure the LEDs are not in backwards. You will have to look at the insides of the LED to see the difference in the leads, magnifying glass helps. Compare to ones that work.

The LED housing will have a flat on one side to denote the cathode (which is the shorter lead).

 

[franz bolo]

From the picture, the circuit board (PCB) is the cheaper SRBP (something Resin Bonded Paper, if I am not mistaken) where the copper track comes off easily as compared to fibreglass version.

Thanks for all the suggestions!!!

Here is the kit I bought:
http://www.vellemanusa.com/us/enu/product/view/?id=351177

Here are the specs:
http://www.vellemanusa.com/downloads/0/manual_mk119.pdf

If I have to buy new LED's, how do I know what size? Also, how do I test them?

FB

 

[tim]

^ They look like T-1 LEDs. You can test them by connecting them to a 3 V power source (only briefly if you don't include a series current limiting resistor).

 

[hyperdyne]

If you had solder between the LED legs, you could of also blown out the output of whatever IC is driving the LEDs. You effectively shorted it out, which most ICs dont tolerate well.

 

[franz bolo]

Thanks for all the info!!

The device is now in the hands of someone more capable than me!!

FB