Cap leak cleanup - pad won’t take solder

[98pacecar]

I’m working through a dead MK1 sound board. Pulled the 3 caps that power the amp and found some minor leaking. Cleaned it up, doused it in flux, but I can’t get the top pads to take any solder. They are fairly heavy traces, so I bumped my temp to 750 from 650, but still no luck.

Any tricks to be sure I’ve gotten all the nasty stuff off?

 

[Stupid Dufus]

Not sure what type of caps are on on MK1, but guessing you're talking about surface mount?

Whenever I remove surface mount caps I clean the pads with isopropyl alcohol (90+%). If pads won't take solder after that, I'll clean again and then rub a fiberglass pen over them and clean again with IPA. Repeat as necessary.

After that it usually takes. Had to do this for some PC Engine Duo and Game Gear repairs.

But if you've tried that, not sure. With the above process I can keep my iron at 320 - 370°C (~600 - 700°F) without issue.

 

[98pacecar]

Nah, these are through hole. I didn’t think about using my fiberglass pen. I’ll dig it out and try it tomorrow. Thanks!

 

[GeekMan1222]

Yeah sounds like the copper is not clean enough for the solder to adhere properly.

You can use a fiberglass pen as mentioned before to scrape away some of the corrosion and gunk left on the pad. If your in a pinch you can take something sharp or that has an edge and VERY gently scrape at the pad a little. Make sure you don't scratch the pad off cause it sounds like you used a lot of heat on it already which will cause the pad's glue to loosen if too much is used. Rubbing alcohol to clean the pad more and flux might also help a lot too.
Also you should try to re-tin the pad and wick away the solder first before trying to solder the leg through if you can manage it, but its not a requirement its just something I like to do my self.

Its not the end of the world either if the pad does come off or gets loose due to all the heat and messing about with abrasion from the fiberglass pens or etc. You can just take the leg of the capacitor and solder it directly over the trace or to a near by component that is on the same circuit. There's videos online about that process so I wont write it all out here because it all depends on the situation.

 

[98pacecar]

The fiberglass pen did the trick. Didn’t take much scrubbing either. Thanks for the reminder!

Sound board still doesn’t work, but that’s another topic. Lol!