Results 1 to 6 of 6
  1. #1
    mtbr member
    Reputation:
    Join Date
    Jan 2010
    Posts
    21

    Another Newbie Screw-up

    A few months ago I put together a light using Cutter's 3 XPG/bFlex kit. It worked great and then I decided to "improve" it... I was trying to add an LED indicator light to show when the unit is on ( I use it for a daylight running light). While futzing with it, the wiring to the LED PCB came loose. After re-soldering the light wouldn't work.

    I posted the problem and someone suggested carefully scraping away some of the insulation and trying to solder on the exposed wires. I did that and still nada.

    I test the circuit and and all is good from the battery to the bFlex and from the bFlex to the LED PCB. Did I scrape the right area? Have I totally screwed up the LED board? Would I be better off getting a new one?

    I've attached a close-up photo of the disaster area.
    Attached Thumbnails Attached Thumbnails Another Newbie Screw-up-led-board-001.jpg  


  2. #2
    mtbr member
    Reputation: troutie-mtb's Avatar
    Join Date
    Sep 2007
    Posts
    3,046
    those solder joints are not making contact I suggest redoing them after a good clean and flux
    Last edited by troutie-mtb; 08-14-2010 at 11:24 AM.

  3. #3
    mtbr member
    Reputation:
    Join Date
    Jan 2010
    Posts
    21
    Troutie,

    Thanks! Another Neewb question- what are Soler joints? What would be the best way to clean the PCB and what type of flux should I use?

  4. #4
    mtbr member
    Reputation: troutie-mtb's Avatar
    Join Date
    Sep 2007
    Posts
    3,046
    Quote Originally Posted by Dave T.
    Troutie,

    Thanks! Another Neewb question- what are Soler joints? What would be the best way to clean the PCB and what type of flux should I use?


    Sorry Dave

    Typo on my post I meant the solder joints you have done don't look like the solder has flowed onto the pad

  5. #5
    mtbr member
    Reputation:
    Join Date
    May 2010
    Posts
    333
    Yeah, looks like a bad joint - you are looking to warm up the pad, not just getting the solder to melt.

  6. #6
    mtbr member
    Reputation: HuffyPuffy's Avatar
    Join Date
    Jun 2008
    Posts
    890
    It is hard to tell, but when the wire broke loose, did it appear to pull some of the pad and trace with it? From what you posted it sounds like you had soldered to the + and - pads but it did not work, since there is nothing connected to them now I'd guess that you either removed the wires or they did not solder correctly and fell off? Have you tested the trace from the + and - connections to the LED's they attach to with a meter to verify that there is an electrical connection to the LED's?

    Also since this is on an aluminum board it will be tougher since the heat will dissipate and the solder will not flow as well, that is probably why the solder balled up as in your pic (or the copper trace/pad was removed and the solder had nothing to attach to). It should flow onto the pad and flatten out - though if the pads were lifted off when the wires broke off, then you will need to solder to the traces that are left which is what the scraping was all about. Alternatively you may be able to solder a jumper to the LED contacts themselves (pics appear to show a small solder bead on each side of the emitters that could be used to connect - and then solder the jumper wire to the wires from the driver - the jumpers would be very delicate though so I'd glue them down to the board once the connection was confirmed OK. Only solder to the LED's as a last resort since the connection would be very fragile and you may end up having to re-work them later after the light takes a hit (and since these are series LED's that would suck out on the trail - don't ask me how I konw). This board does looks salvageable, good luck! I would not use a lead free solder for this since they are more difficult to use normally.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •