Detecting cold solder joints - favorite methods

[kgreene]

what are your favorite methods used for tracking down cold solder joints?

As everyone knows, this can be a huge problem particularly in older vintage amps.

I tend to do a visual inspection first, with a magnifier, then I push, pull, and tap my way through the amp. But I can't tell you how many times I end up finding more problems later, no matter how meticulously I examine the amp.

I'm curious to hear about other folks approaches to this part of servicing amps.

Thanks, Ken

[Markusv]

I tend to ask the customer if I may re- flow all solder joints on their amps
(It takes some time and adds to the cost but then you know your joints are not where the problem is)
Then I go and replace faulty stuff as I discover them along the way
Quite often the amp has previously been worked on and the gobs of solder you sometimes get just blows the mind

I also tap, and tug each joint once done

M

[xtian]

When you reflow solder, do you suck out the old stuff and reapply fresh, or just apply heat only?

[Markusv]

If is a neat joint with minimal solder I may just heat and add a dab
Normally I like to get the old stuff out first though

.edit...
And I realize that's more of a re- solder than just a re-flow

[kgreene]

Re-soldering an entire amp can be quite laborious. Plus, there are some problems you can create just by doing it, e.g. Fender amps that have the double layer eyelet material, solder can clump between the layers and cause problems - I have seen this from the factory many times, and it's a pain in the neck to deal with!

Removing the old solder is probably the best way to go, but if you just need a touch up, dabbing a tiny bit of flux on the connection before re-heating helps establish a good flow.