Does anyone have any experience in fault finding and fixing circuit boards of LED's? I have several smoked Clear Alternatives tail lights which all have faulty or intermittent sections of LED's. As they are a sealed unit, I am going to try and cut a lens off clean from one, and a body from another so that I can make one working light. Can anyone tell me the best process for finding the fault and repairing it? This is what I'm looking at.

* Last updated by: sweetfa65 on 6/26/2014 @ 5:46 PM *

Its probobly broken solder joints or rivets. Its a simple setup. Positive and negative bus bars run horizontal and the leds are soldered or rivited in between.

You could also have a bad lead wire coming from the plug to the board.

If you use a fluke meter or any other meter that can read capacitance, you can test the leds with it. The leds are basically fuses in this arrangement. They will light up wvhen u go across them.

Biggest hassle is getting the lens off cleanly.

* Last updated by: fatsix on 6/26/2014 @ 7:14 PM *

Thanks fatsix. Yeh, I'm going to try and dremel a couple of lights so I end up with a clean lens and a clean body, and I'll just sacrifice one of each. I've got 3 lights that are f'd anyway, and one has a broken lens too, so I've got nothing to lose. I saw the work you did on yours. Good job. So with the LED board, am I just testing the LED for resistance (open or closed), or am I looking for a break in power on the printed CCT board? I've got a digital multimeter, but I'm not great with them. Or do I just go around the connections of all of the LED's in the faulty area with a soldering iron and re-melt the solder? I guess I'm better off to pick the light that has the least problems too?

* Last updated by: sweetfa65 on 6/26/2014 @ 8:25 PM *

You can check the resistance of each wire from the plug to each spot on the board. Can't do LEDs like that because you will always show closed because of the others that are connected in parallel. Need to apply voltage. 9v battery will work. You could power each section with it then use your probe to read across the and press them down to see if its the connection or what.

Im going to cut another one open to paint. I'll take a better look at how you can test it. Generally LEDs are used as fuses, so you would be looking for opens. Is that picture in the first post yours? All I have are stockers, so the boards are probably different, but the concept is the same.

Thanks fatsix, I appreciate you walking me through this. Yes, that's one of my faulty lights. I got a base off clean on the weekend by sacrificing the lens and using a rotary tool to tidy it up. Next is to get a lens off clean. Then I can start trying to fix the LED's out of one. I'll try to get a pic of the board. The stockers look much simpler, given that they only have a dozen or so LED's. These have 14 rows of about 8 LED's on the park side, and about the same on the brake side.

Yup. Need pics. I'm still betting on a cold solder joint. Especially if they are tested good and being delivered damaged. Hopefully this rumble concept unit is somewhat similar. Just picked it up off ebay to dick around with.

* Last updated by: fatsix on 6/30/2014 @ 10:56 AM *

I had a look at the board last night fatsix. I can see where the live tracks run and the LED's sit in-line. Like -O-O-O-0- kind of thing. As you said, like an inline fuse soldered onto the board with 2 legs. I should be able to work it out without too much trouble, as long as the CCT board is ok. I reckon it's most likely dry joints too. If not, I'll have a couple of boards that I can switch components around. I'll start with the main power wires and such where they connect to the boards, then move onto testing the first LED's in each section that are not working. I guess putting an iron on all the LED's is probably a good idea anyway. I'll let you know how I go once I get a clean lens and body sorted.

Remember positive wants to get back to ground/negative. Make sure you have positive at the tops of the led strings. Should be an Aha! moment when you do find it.