On Jan 13, 6:55*pm, tony sayer wrote:
Recently I have needed to recap a few motherboards (not usually an
economic exercise - but these were custom form factor jobbies where
replacements are not readily available), and they were a right PITA to
work on. Obviously multilayer, and since the caps are on the power
regulation sections, probably connected to fairly heavy power plane
traces in the board. Component removal was very difficult - often taking
excessive time for the joint to reflow. Tight pins in close holes with a
small annulus. However cleaning the holes for reuse proved impossible
with any of my normal irons. In the end I had to resort to using a hot
air paint stripper with small nozzle on the end to get enough heat into
the area to be able to suck the holes clear!

I was wondering what suggestions those of you who do this daily had to
offer?

We had a similar problem on a Harris VHF/FM broadcast transmitter where
they recommend you break the cap off and solder to the wires that are
left behind;!..

That's it. The other problem with desoldering TH parts from multilayer
boards is its liable to damage connection between buried layers of the
pcb, which is then a nightmare to repair.


I see a couple of potential problems with tackling electronic repairs
in one page on a wiki - or anywhere else, aimed at the inexperienced.

First, no matter how long the page, a beginner simply isnt going to
end up competent after reading it. So to enable a newb to get a repair
done requires skipping key info, which will inevitably result in
problems and unsuitable advice.

The other issue is that popular myths have a habit of coming into
discussions about electronics in largely non-expert forums.


NT