[Coco] Sort of OT: Recapping

[Arthur Flexser]

I'd suggest a variation on what you mentioned with a "fabric pin" (commonly
called a straight pin, I think).
I have had success in similar situations holding the straight pin with a
needle-nose pliers, grasping the pin with the thinnest part of the pliers
so as not to siphon off too much heat, and heating the pin while pushing on
it and pressing it into the hole.  You want to grasp the pin well away from
its point, again to avoid siphoning off too much heat into the pliers,
holding the soldering iron tip against the end of the straight pin, while
you push the point into the hole with the pliers.  Possibly cutting off the
point of the straight pin might be helpful, though I have not found this to
be necessary.

Art

On Fri, Nov 27, 2020 at 4:10 PM Salvador Garcia via Coco <
coco at maltedmedia.com> wrote:

> I am trying to recap a motherboard which is not from a CoCo, but I thought
> this subject might be of interest to the CoCo community since recapping
> seems to be a fairly common occurrence in the vintage computer community.
>
> I noticed three bad caps on the MB. I have done recapping before, so no
> big deal, or so I thought. My soldering irons, 25, 30 watts, would not melt
> the MB's solder.
> I got a Weller 1010 (70W) and this helped. I managed to remove the caps,
> but I still had a hard time melting the solder and two of them came apart
> and pieces of the pins (3 to be exact) are still in the through hole.
> Suggestions included applying clean solder and flux which I did. The clean
> solder helped, but the flux only left a dark stain on the PCB, so I
> discontinued its use.
> I can't melt the solder from three of the through holes where the pins are
> located. I've provided links to pictures. One of the cap's pins can clearly
> be seen sticking out of the MB for the cap in front of the choke (or
> inductor, not sure). The fat cap behind the choke is the one that I managed
> to successfully replace.
> I applied heat to the solder pad and tried to push the stuck pin with a
> fabric pin (the kind used in new clothing to hold the folds), was
> unsuccessful. I thought about grasping the protruding pin on the solder
> side, but did not because I figured that the pliers used would dissipate
> heat and make it harder for the solder to melt.
> In one case, I ended up using a very fine hand drill bit to remove the
> last remnants of solder from the through hole. This won't work where the
> cap's pins are still stuck in the through hole.
> At this point I've used up my options (and patience). Does anyone have any
> recommendations on how to get the stuck pins out? Hopefully this discussion
> will be fruitful to other recapping their CoCos and other computers.
> Links to pics follow, thanks much, Salvador
>
> Caps. I am replacing three caps. The fat one in the back (behind the choke
> or inductor), which is already replaced, the smaller one in front of the
> choke, and the front left. The MB did not have a cap at the front right
> location. Note the cap's pin still soldered to the MB (in front of choke).
> https://drive.google.com/file/d/1heHQ3TfpMVcubUvvcUYxxFCOvEn9woKl/view
> Solder side, The dark spots are from the flux that I applied to determine
> if this would help to melt the solder.
> https://drive.google.com/file/d/1bLeOGqPTrGhhm3Xiyt7DGKq3Av_4BZ9O/view
>
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