have been trying to replace a capicitor on this inherited pcb. Sadly the negative pad for C6 (Orange circle) seems to be missing. Can anyone advise how best to get a capitor seated here?


PS no idea what’s going in the with the blue circle....

enter image description here

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    \$\begingroup\$ Stand the cap up on end (tombstone) on the good (?) pad, and solder a small wire (like a #30 solid) from the other end of the cap to where ever the connection is supposed to go. What a mess. \$\endgroup\$ Commented Jun 10, 2020 at 20:43
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    \$\begingroup\$ start by cleaning the area throughly ... use isopropyl alcohol and a toothbrush ... do not use rubbing alcohol, because it contains oil \$\endgroup\$
    – jsotola
    Commented Jun 11, 2020 at 2:30
  • \$\begingroup\$ And also remove the old solder remains. You can then probably scratch away the solder mask with a scalpel around the via next to the pad and then solder onto the exposed copper. \$\endgroup\$
    – Lundin
    Commented Jun 11, 2020 at 13:09
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    \$\begingroup\$ If I had to bet, I would say that this failed capacitor was connect to the via in the lower left of the orange circle. There seems to be a copper piece exposed and even the shadow of the trace. \$\endgroup\$
    – mguima
    Commented Jun 12, 2020 at 20:58

1 Answer 1


Good luck man. It's doable, and I've done far trickier things, but I've been at it for a long time.

What I would do is this:

Obtain the following: A single strand of copper wire - Like a little scrap from a multi-strand cut-off. THis is not going to be 'high current' - Even a very thin wire will do

Good tweezers

A 'fine tip' soldering pencil (like <1mm width at the tip)

Very thin solder - Thinner than whatever you have on hand. They sell stuff that's like a 40 AWG wire or so. That's what you want here.

A microscope or other magnification means if possible

Start by scraping the solder mask (the green covering) off that via that's located below and to the left of the missing pad. Use an exacto-knife, but scrape in the OPPOSITE direction of "cutting"... i.e. drag the tip a few times, and the green-stuff will sorta crack & break up. DON'T CUT INTO THE COPPER!!! Use a fresh blade if possible, makes the work much cleaner and faster.

Solder your wire to that via. Bonus points if it fits INSIDE the via (but it might be clogged with solder-mask)

Clean that cr*p solder off the good pad with a piece of solder-wick (cut it down to a thin strip if you need - Don't use a huge wide piece - It'll act like a heatsink and stop your process)

Put a small blob of solder on the 'good' pad, let it cool.

Hold the new capacitor down on top of the solder blob, and hit the blob with your soldering tip - THe solder will 'reflow" and pull the capacitor down (guide it gently with your tweezers).

Now it'll be easy to solder that wire to the other side of the cap

If you dwell on the cap for more than a second or two, throw it away and get another one. It's super-easy to fracture a ceramic cap with too much heat.

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    \$\begingroup\$ Thanks man, that kinda confirmed what I was thinking but the recommendation of soldering pencil and solder size is great. Thanks again. \$\endgroup\$
    – Adam
    Commented Jun 10, 2020 at 21:04
  • \$\begingroup\$ @Adam I have a spool of the stuff that'll probably last me 17 lifetimes ;) If you wanna send me a self-addressed stamped envelope, I'll drop a few inches of it in the mail for you "free". PM me if interested. \$\endgroup\$
    – Kyle B
    Commented Jun 10, 2020 at 21:06
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    \$\begingroup\$ Very kind, thanks. Think there may be some similar stuff at my parents place, I remember seeing a box full of various soldering stuff - I’ll be raiding it I think! \$\endgroup\$
    – Adam
    Commented Jun 10, 2020 at 21:13
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    \$\begingroup\$ @Adam I forgot the most important part ---- PRACTICE ON A SCRAP BOARD FIRST!!! ;) \$\endgroup\$
    – Kyle B
    Commented Jun 10, 2020 at 21:15

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