[Coco] Desoldering tools

[Jim Veneskey]

Re: desoldering chips - assuming you don't want to preserve them, this is
the method I use.

I have a Weller soldering station that I've had since the early 90's, I
think the temp is set to 675F.
It has the same needle (conical) tip that I used when I was doing SMT board
repair for Telxon (long gone)
I also have a heavier non-temp controlled soldering Iron with a wedge tip
that I use for desoldering.

Assuming I don't care to preserve the chip, I will snip the leads as close
to the package as possible, this ensures sufficient mass for my
somewhat unorthodox method of extracting them.

Once the "body" of the chip has been removed, and just the leads remain, I
place something like a large pink eraser on my bench, and flip the board
over (solder side is now up) and lay it so the rows of leads are now close
to the eraser.

The eraser is to ensure the leads I left are now above the surface of the
bench and are not touching it.

It is then a simple matter of using my larger soldering iron to heat up 1-2
leads at a time (applying more solder if needed) while I am now slightly
lifting one end of the board up about an inch over the eraser.
I then simply allow the board drop back down onto the eraser, and inertia
causes the pin to be spat out onto my bench.
The longer the leads, the more mass for inertia to work with.
Once all pins have been ejected in this fashion, then it's usually a simple
task to clean up the holes with a spring loaded solder sucker.

I now put the heavier soldering iron away, and get out my finesse one and
solder a socket in place.
Finally, clean up the area on the board with toothbrush and rubbing alcohol
to get rid of any flux.

 Jim

On Thu, Oct 19, 2017 at 2:20 PM, Salvador Garcia via Coco <
coco at maltedmedia.com> wrote:

> Since desoldering was mentioned in the thread titled "I've killed my
> CoCo", I thought I'd ask about what tools are used to desolder chips.
>
> Ed mentioned that different techniques work for different people, so I am
> interested in hearing what others have to say.
>
> Lately, I had to desolder a bunch of electrolytic caps (not CoCo related)
> and I found that it took a while for the solder to melt and release the
> cap's lead.
>
> In the past, I've used a desoldering pump like this one:
>
> https://www.digikey.com/product-detail/en/17537/243-1184-ND/1992578
>
> While effective, I found that I needed to press it against the PCB because
> if I didn't, the "kickback" from the pump action would move the pump away
> from the PCB, not effectively sucking the solder. Also, I found that for
> me, this device worked best when I applied the heat on one side of the PCB
> while pressing the pump's tip to the other side and releasing it when the
> solder melted. However, this was not always possible and sometimes I found
> myself having to melt the solder (on the PCB''s solder side) then quickly
> pressing the pump's tip against the PCB and releasing it. This worked, but
> rather clumsily. Currently, the pump has seen better days because it no
> longer locks in position reliably.
>
> When I had to remove the 6809 from my non-functional CoCo 3 I used solder
> wick. This worked, as evidenced by the silvery finish on the wick, but I
> have taken too long to remove all the solder and I still have not been able
> to free all the pins.
>
> I saw a desoldering gun in action at a recent Maker event and was
> impressed.
>
> I don't desolder often, but when I do, I really need an effective way of
> doing this. I was looking into buying a desoldering gun, but the prices
> hover around $150 USD and this is too expensive for me for just occasional
> use.
>
> I hope other share their experiences and the tools that they use, perhaps
> recommending specific products.I certainly am interested in learning from
> others' expriences :-).
>
> Thanks, best wishes, Salvador
>
>
> --
> Coco mailing list
> Coco at maltedmedia.com
> https://pairlist5.pair.net/mailman/listinfo/coco
>