How to resolder a cold solder connection?

My last bottle is about 25 years old. I bought four quart bottles of it for $2.50 each from a surplus store in Dayton, Ohio. The others have been used up.

Right. I'm happy they know which part is bad, roughly how to fix it, and the write webpages for people like me.

I hate to say this but none of my solder is marked R, RMA, or RA. The labels says nothing except that they have rosin.

Radio Shack solder mostly. I've used up other things I had.

Also the Radio Shack flux paste doesn't have an R-rating. It says nothing about what kind of flux it is.

But the repair today was postponed, so I have time to go farther away and buy liquid flus. I have another errand to do nearby.

I can do that.

I can do that. It's still necessary with liquid, right?

Does that also have to be R, RMA, or RA?

Then it is very probably R (rosin only) RMA (rosin mildly activated) or RA (rosin activated). No worries.

If it is the SP-44 stuff, you are in luck because it is compatible:

As Smitty Two says, you *can* thin your paste with

Yes indeed. Extra points are rewarded for cleanliness.

Yup. Most specifically NOT 'acid' or 'plumbing' flux. Sorry for shouting but we don't want your relay to turn green and fall apart.

--Winston

Gotcha! You and Smitty Two.

I'd put in a plug for RA flux. I have a lot of old parts that I still use a lot (e.g. over 10,000 RN55C resistors), and RA flux makes them solder like new.

Cheers

Phil Hobbs

Okay, I'll see what they sell.

That'll work! My fave Kester 186 is RMA and it does a stellar job as well.

--Winston