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I need to replace the C219 of the following SM design:

enter image description here

Is it possible to accomplish this task using regular soldering iron (used for through the hole design soldering) and some solder? Can I use a regular legged capacitor to replace the capacitor with, or does it have to be SMT? I have extra set of hands available, so holding it in place should not be an issue.

Are there any precautions I should take as to not damage the board (very expensive)? There is some PSU wires next to the part (can be seen on the right) that apparently can't withstand a lot of heat. What temperature should I keep the iron at?

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  • \$\begingroup\$ What vibration and shock limits is the PCB designed for or subject to? \$\endgroup\$ – Andy aka Feb 3 '17 at 16:26
  • \$\begingroup\$ It would be easiest to use two irins, so you can heat both terminals at once, and pick the capacitor up using the irons as tweezers. \$\endgroup\$ – Peter Bennett Feb 3 '17 at 16:33
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    \$\begingroup\$ What makes you think C219 needs to be replaced? \$\endgroup\$ – pericynthion Feb 3 '17 at 16:34
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    \$\begingroup\$ @pericynthion I read that it's a common issue with the unit, and the faults match the description. \$\endgroup\$ – Tony Feb 3 '17 at 16:58
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    \$\begingroup\$ Roland JP8000. Seems to be a common problem. \$\endgroup\$ – JRE Feb 3 '17 at 20:02
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Yes it is quite easy. If you have no experience in this sort of thing, either get someone else to do it or practice on boards that are trash.

With that kind of part you can suck most of the solder off each pad with some fresh solder wick and then melt one lead and gently tilt the part away from th pad, freeing that end, then melt the other side and it should come right off.

Clean the pads up with solder wick (so the part will sit down flat), solder one lead then the other to center the part on the pads.

enter image description here

Strongly suggest getting a proper SMT part. If you must hack something in, there are techniques to do it safely, but I doubt that is desirable.

Try about 320°C for the iron tip temperature. Obviously you want to use a nice thin tapered tip that is small enough that it is suited to the job and avoid melting that wire you mentioned. (both photo credits to Digikey)

enter image description here

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    \$\begingroup\$ By observation I would believe it to be electrolytic - 16V / 22 microfarad. \$\endgroup\$ – Adam Lawrence Feb 3 '17 at 17:35
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    \$\begingroup\$ Super-thin soldering iron tips are terrible in practice. they don't heat the pad to the temperature of the iron, so it is really easy to get bad joints or tear the pad off. A small chisel is a much better shape for this kind of work. Trust flux to keep solder from bridging. (if you have an adjustable-temperature iron you can crank the heat up and use a small tip. But this is not beginner technique.) \$\endgroup\$ – markrages Feb 3 '17 at 17:53
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    \$\begingroup\$ Agree 100% with Adam. SMT aluminum electrolytic. Get a low impedance type if you are not sure. \$\endgroup\$ – Spehro Pefhany Feb 3 '17 at 18:46
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    \$\begingroup\$ This pictured tip is too small for this job and will make it unnecessarily difficulty. As SMT components go this is a fairly large one (it's basically a through-hole component with leads bent through a little carrier-base), so you want effectively the largest tip you can fit in there, especially if one side of the capacitor is connected to a copper pour or heavy trace that might pull heat out of the joint. \$\endgroup\$ – Chris Stratton Feb 3 '17 at 19:01
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    \$\begingroup\$ Yes, a small chisel or spade tip will suit your needs just fine. Avoid pencil tips like alternative facts. \$\endgroup\$ – Doktor J Feb 3 '17 at 19:04
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Yes, you can do that.

  1. Add solder to the pads.

  2. Use a pair of tweezers to hold the capacitor and pull gently.

  3. Heat one pad until the solder flows

  4. Switch to the other pad and heat it until the solder flows

  5. The capacitor should come up off of the board.

  6. If it doesn't come off entirely, don't force it. Repeat the heating of the pads until it comes off all the way.

  7. Remove the excess solder with solder wick. Be careful because this can easily pull the pads off the board.

  8. Tin one pad

  9. Place the new part on the pads - watch the polarity since you are replacing an electrolytic capacitor.

  10. Push down on the capacitor (gently) with the tweezers.

  11. Heat the tinned pad until the solder liquifies

  12. The capacitor will pop down solidly onto both pads.

  13. Remove the heat from the pad

  14. Place the tip of the iron against the junction of the capacitor's free connection and the pad under it

  15. Feed in fine solder (I use 0.5mm solder) to the junction

  16. The solder will melt and wick itself in between the capacitor and the pad

  17. Remove the solder wire from the junction

  18. Remove the soldering iron from the junction

  19. Solder cools, job done

Then follows step 20:

Cuss because the problem is really something else.

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1 - Yes, you can replace it using a regular soldering iron. It has to be thin enough to fit in the space between the targeted component and the neighbooring ones. I've seen technicians adding more tin to the pins, then heating them back and forth until the component moves out of its place. If you have 2 irons, you could do it without this technique.

2 - I do not recommend using a through-hole component on SMD pads, considering that board, according to you, is very expensive. (I've seen pads come off boards because someone soldered wires on them for testing, then accidentally pulled on one of the wires)

3 - Unless you don't really have a choice you can use the a TH component and secure it with some fixating material.

4 - Iron temperature depends on the soldering material you're using, you have to reach a high enough temperature to melt it.

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For removing, consider using chipquick. It is a special type of solder you add to the pads to help remove the old SMD.

Clean all the chipquick off with wick.

You really do not need to have much solder on the pads when added the SMD. You do need the pads to be tinned, and you need to have flux on the pad. Then the solder will flow under. Press the iron tip to the edge of the cap and add the solder. It should flow. Do one side at a time, for the first side you will need to hold cap in place with a tweezers. You can also you a paste of solder and flux that hold the cap in place before you touch it with the iron. You can buy this paste.

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