the little SMDs took my PCB's pads with them.

Discussion in 'General Electronics Chat' started by weezycarneezy, Feb 19, 2013.

  1. weezycarneezy

    Thread Starter New Member

    Feb 19, 2013
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    I'm rebuilding the boards on my old tv thanks to norcal715's 25 minute youtube video. but then this happened and I'm stuck.

    what's the best way to get these 2 new non-polar caps back into my circuit?
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    more or less "SOL"
    But with some through hole caps and jumper wires tied inserted in to the via holes you might be able to rig it back up.

    maybe a little sand paper to get the solder mask off giving you "clean" copper traces that you can tack wires to.
     
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  3. t06afre

    AAC Fanatic!

    May 11, 2009
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    Can you post a more close up picture. And perhaps also clean up somewhat. Technical Alcohol but not liquor:eek: is good for electronics cleaning, be gentle then cleaning
     
  4. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    Where did you get that from? All those caps are polarized aluminium electrolytic caps. Anyway you can see the traces going to those little vias, so you should be able to solder there small pieces of wire and then connect those to the new caps. Don´t forget to glue the new caps somehow to the rest of the board.
     
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  5. weezycarneezy

    Thread Starter New Member

    Feb 19, 2013
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    i think i understand WHAT i need to do. the HOW is what i need help with.

    i've cleaned up and exposed the one remaining trace for the lower cap so i think I'll be okay with that one.

    The top one however...it looks like i have to make holes where the little copper donuts used to be...2 for the left terminal and one for the right. those holes are TINY! what do you use? is there a dremel bit that small? and i don't have that fine a gauge of wire.

    and yes, these two i removed were definitely bipolar in the middle of polar caps.

    while i'm asking questions, what is the voltage rating of the 10uF caps marked CHA 4T3? i was just gonna use 16v


    THANK YOU ALL for your responses!!!
    Sincerely!
     
  6. t06afre

    AAC Fanatic!

    May 11, 2009
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    Here is how I think it may have been. But I will stress that I am not 100% sure. You can probably use some thin wire through the vias. and solder it on the opposite side of the board. As the copper on this side seems to be damaged. I am puzzled how you have managed to damage the board like that. I think you need to practice more on your solder skills. If I was you. I would gotten some scrap electronics and used that for training. Because your board can not take much more damage. After some training you can get back to your TV board. Remember dust and dirt is like poison then soldering. So I would recommend you to clean up even the training board before doing any work. The training board can be cleaned with hot water and a brush. But let them dry before you work on them.
     
  7. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    I would NOT drill thru the board. You can kill connections that way, especially if this is a multilayer board: you just can't get solder into the inner layers.

    Instead look at the board and see where the traces went, and find another component you can solder to.

    Small wire will help, and you may find some very tiny wire inside other wire: pull apart the strands and just use one. If you dress the lead carefully, and use a drop of hot melt glue you may get away without any other insulation.
     
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  8. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    How did you get them out??

    What tools are you using?

    Try a Q-Tip and 90% Isopropyl alcohol

    If that doesn't work, try some 600 grit sandpaper on the end of a Q-Tip GENTLY to see if you can get to copper.

    As ErnieM Stated: Do NOT Drill Through the board! It is most likely a multi-layer board and you'll never get the internal connections back.

    If these pads were ripped off while overheating the board, chalk it up as lesson learned and order a new board.
     
  9. weezycarneezy

    Thread Starter New Member

    Feb 19, 2013
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    see video at 11:00 minutes in.

    http://www.youtube.com/watch?v=p1zhfYHUIIY

    It's such a shame! I have replaced about 200 caps on 2 and a half boards with no problems until this.

    i cant find any copper on the upper cap. no trace of trace.

    i'm soldering at around 700F is that too hot? too cool?

    Also, What is the voltage of the 10uF marked 10 CHA 4T3?
     
  10. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Yes, your iron is way too hot.

    Typical temperature is 525ºF to 575ºF, (~260-300ºC)

    Best way to remove components is some good solder with flux, and maybe some extra liquid flux. Add a bit of solder (leaded, not lead-free) to each joint so the two solders mix, and end up melting at a lower temperature.

    I use either Chip-Quick 0.018" dia solder, or Multicore 0.015" dia solder. The chip-Quick is great for Surface mount rework, while the Multicore is great for assembly of Surface Mount and through hole.

    With the very thin diameters (26-28 gauge wire size), the solder doesn't wick away much heat before melting, and the exact amount can be precisely applied.
     
  11. t06afre

    AAC Fanatic!

    May 11, 2009
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    At least from my point of view. Any use of force is a no-no. Therefore the trick of bending the caps look quite dodgy to me. I also agree that your temprature is set to high. That may have caused the glue(that glue copper to the boad) to fail
     
  12. JMac3108

    Active Member

    Aug 16, 2010
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    I agree - do not drill the board. Unless you have the PCB documentation and can check what is on internal layers (if there are any) don't ever drill.

    Do you have the schematic? If so, you can sometimes find a nearby component that is the same net that you can just solder a jumper wire to. For example if a ground pad is lifted when you remove a cap, you can glue the replacement cap in place and solder it to the ground on an nearby cap.
     
  13. sheldons

    Active Member

    Oct 26, 2011
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    never never drill a plated thro board like that.....what you need to do is with the aid of the service manual find where the affected tracks made connection to and wire from the nearest accessible point to your replacement caps.....you may need to glue them in place first.....the reason why i say dont drill through the board is that you can easily damage connections on the underside of the board creating more faults ....give me the full model nr and make and ill see if ive got the manual for you .
    the original parts that were fitted are also glued in position then soldered-not by hand but by machine..... also if that was a plated through multi layer board drilling through will scrap it
     
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