This is a Halo light that came out of a fog lamp on my car. It had a few dead LEDs, 4 or 5 out of 50, all in a row. When I inspected the board, I found that it was badly corroded, and it looks like the original solder has been eaten away. Does this look salvageable? this is after I have scrubbed with a toothbrush, first with baking soda, then rinsed with distilled water, then isopropyl, then water again. I think I am capable of soldering it if I go out and buy a very fine tip for my iron, and this particular LED board costs about 100 bucks to replace.

Any advice on how best to repair/resolder these components would be helpful, thanks in advance!

 

Does this look salvageable?

Yes, I think so. Do you have a multimeter? It would be nice to identify where there are gaps in the trace. I'd probably take a thin piece of uninsulated wire and use the soldering iron to tack it down to the ring, to bridge any gaps. You might need a few new resistors and LEDs, depending on what you find with the meter.

 

hi JDR,
Welcome to AAC,
If you can clean the broken tracks so that the copper is visible, lightly flux the cleaned track.
Using lengths of bare solid/tinned copper wire, say 1mm OD, solder the wire along the broken track gaps, be generous with the cut lengths, ie: plenty of overlap wire to track. [DONT over heat so the copper track lifts off the board]
Once done , test the LED lamp panel, if OK, clean off any residual flux and varnish all the track and wire. [ borrow your GF's nail varnish if you have no other varnish on the shelf]
E

EDIT:
If there is corrosion the plated thru holes, insert a piece of 1mm solid wire, solder both ends

 

Yes, I think so. Do you have a multimeter? It would be nice to identify where there are gaps in the trace. I'd probably take a thin piece of uninsulated wire and use the soldering iron to tack it down to the ring, to bridge any gaps. You might need a few new resistors and LEDs, depending on what you find with the meter.

I do have a multimeter, the copper trace seems to be unbroken all the way around, if a bit scratched up. I think you may be right about the resistors, they read as 0/open when i tried to ohm them out, but i may not have been getting good contact because there was so much corrosion. I will try again now that I cleaned it up a bit.

 

hi JDR,
Welcome to AAC,
If you can clean the broken tracks so that the copper is visible, lightly flux the cleaned track.
Using lengths of bare solid/tinned copper wire, say 1mm OD, solder the wire along the broken track gaps, be generous with the cut lengths, ie: plenty of overlap wire to track. [DONT over heat so the copper track lifts off the board]
Once done , test the LED lamp panel, if OK, clean off any residual flux and varnish all the track and wire. [ borrow your GF's nail varnish if you have no other varnish on the shelf]
E

The track was covered by a white film, that was gone/eroded when I removed it from the lamp housing, exposing just the section you can see. I believe it is unbroken.

 

I do have a multimeter, the copper trace seems to be unbroken all the way around, if a bit scratched up. I think you may be right about the resistors, they read as 0/open when i tried to ohm them out, but i may not have been getting good contact because there was so much corrosion. I will try again now that I cleaned it up a bit.

That one in your photo looks like it was poorly placed. It may have been damaged by the corrosion and subsequent cleaning. I normally wouldn't be suspicious of a resistor unless there is physical damage such as this.

You could also make yourself an LED tester. A 9V battery with a 470Ω resistor and test leads works pretty well. Just try to observe the correct polarity. A 5V USB supply with a resistor in the range of 100-330Ω should be fine also.

 

The track was covered by a white film, that was gone/eroded when I removed it from the lamp housing, exposing just the section you can see. I believe it is unbroken.

hi,
Now the white protective film has been scraped off, its important that you varnish the bare areas.
E

 

hi,
Now the white protective film has been scraped off, its important that you varnish the bare areas.
E

For sure, before reinstalling and after repair, I intended to seal it in silicone.

 

For sure, before reinstalling and after repair, I intended to seal it in silicone.

Be sure to use the kind that does not off-gas acetic acid (vinegar smell).

 

Be sure to use the kind that does not off-gas acetic acid (vinegar smell).

I have some automotive grade silicone sealant that I have used before to seal up LED projects, does not smell of vinegar like aquarium sealant silicone does, i figured that would work ok. I suppose I could varnish with nail polish first just to be safe.

 

I believe that all you need to do is to resolder the resistors to the board. They look originally solder starved.

+1 on covering the copper once repairs are completed.

 

Thanks everyone for your help, I will try repairs tonight and post results!

 

Question: are both of those components pictured resistors? Because the ones labeled 301 show a resistance matching that number. But the other one, even ones on a known good board read 0. Also, the lights work if I just short around that one. I fixed the one labeled 301, but its messy and I almost ruined it because the finest tip I could buy wasn't fine enough. If there are a bunch of the same resistors already in that ring circuit, will losing one be that detreimental? I accidentally desoldered it from the board,and getting it back on may be beyond my skills and equipment.

 

Both are resistors. One is 300Ω and one is 510Ω.

What kind of an iron are you using? It should be a breeze to resolder.

The board is more than one circuits, so leaving out one will possibly damage that circuit. Best to scrounge around for another 510Ω and replace the one on the board.

 

25 watt with a 3mm pointed tip. I got two pieces of copper soldered in as replacement pads, the old ones were just too corroded and would not take solder. Now I just have to get a new resistor and it will work! The old one had no metal left on one side, so its shot.

 

Also, am I correct on thinking any 510 ohm resistor will work? It doesn't have to be surface mount, resistance is resistance right? I dont care if its ugly. I'm wondering if I can scavenge one from an old junk bit of electronics.

 

Any 510Ω that you can fly in will do the job. Just be sure that you have the necessary clearances if you use something different than a SMT.