[AH] Trim-pot debacle (ADVICE PLEASE!)

[Brett Duggan]

In my experience, any relatively cheap component that has more than 2
solder connections to a PCB should be sacrificed (i.e. destroyed) so that
you have access to both sides of the PCB. 

For example, let's say I need to replace a cheap 28-pin IC socket with a
higher quality one.  I destroy the cheap socket by cutting into pieces
with wire cutters (or a small saw, you get the picture), so that each
piece only has one PCB solder connection.  Then I grab the piece on the
top side of the PCB with a pair a pliers while I heat the solder 
connection on the trace side of the PCB with the iron.  The piece slides 
out easily.

Now, if leftover solder is still plugging up the hole on the PCB, I heat 
it once more on the trace side while I use a solder sucker on the top 
side to suck it out.

I do not know if this would be considered good procedure by any of the 
other DIY'ers, but I know that it works quite well for me.

Good luck,
Brett D

> Basically, I was having a hard time desoldering and removing the trim pots.
> VR3 and VR5, I believe.  I had gone through numerous passes of heating the 
> traces, applying the solder wick (or bulb -- I tried both), and then
> applying firm but gentle upward pressure on the trim pots from the
> other side.  Not the easiest task with only two hands, as most hardware
> techs probably already know.  No luck.  After yanking on one of the 
> trimmers just a little too hard, one of the legs broke off in the hole.
> 
> I couldn't believe it!  At this point, tired and resigned, I made 
> the decision which would start the real downhill slide:  I grabbed a pair
> of small wire snips and a pair of pliers, and used them to wrench the
> trimmers off the board.  If they wouldn't come through gentle persuasion,
> then force it would be!  It felt good at first, but soon afterward came
> the sinking feeling.
> 
> Fatal mistake?  No...I was able to tack solder three of the leads directly
> to the top board traces, surface-mount style.  (Only four leads were needed
> total
> because two leads of each pot were shorted to each other.  See archives for more
> detailed info on the mod itself.)  The fourth lead was more elusive, though.
> The solder joint just wouldn't take.  I don't know whether it was because the
> trimpot pin was leeching heat away, or whether existing heat damage from one
> of my other connections oxidized it, or what.  I tried using a little bit of
> steel wool to clean up the trace, but no luck.