micky wrote:
http://www.tegger.com/hondafaq/mainrelayfix/index.html

Next to the fourth picture, it says:

"Removal of old solder As much of the old solder as possible was
removed in preparation for re-soldering. It is possible to simply
re-flow the old solder, but this method is better. "

Does anyone agree with that?

Yes. Re-flowing is *possible* but risky, because
it generally results in a oxide-polluted 'cold' joint.

In either event, it is critical to apply separate flux
to the joint to float oxides out during the soldering
process. The improvement in quality is substantial.

This ia an automotve electical device, a Honda main engine relay and
fuel pump relay, with a resistor and 3 diodes, and has 24 solder spots
on the circuti board. It seems to have a lot of cold solder problems
after a few years.

When you guys resolder, do you just heat it up and add a little more
solder, or do you clean off the old solder and start fresh?

Honestly, I dab flux on the joint and reheat. It is quick
and effective. For joints that appear cold after that operation,
I remove the old solder, re-flux and use good quality leaded
solder. (Then *always* clean with a 50/50 mix of alcohol and naphtha).
That hasn't failed yet.

Thrifty guy that I am, it never occurred to me that people would
routinely do the seocnd.

After your first 10 repairs it goes a lot faster.

He calls it dry solder. Maybe that's the automotive term.

He meant to say:
""Cold" solder joints (a frosted appearance),"

Here is a classic example. Note the frosted
appearance of the solder and the lack of 'wetting'
on the pin:
http://upload.wikimedia.org/wikipedi...lder_joint.jpg

--Winston