[dconant]

Hello, Been working on a Philco 60 that needed to have a grid cap wire replaced coming out of an IF can. I removed the coil assembly and cut the grid wire close to the staple that held it. Done this before on another 60. I was just going to solder the new wire on and go but when I went do that I could not get the original solder to melt even with a Weller 325 watt gun. Oh no now what? I did manage to scrap enough insulation off the wire and solder on the new wire. Whew! What was that original solder or wasn't it solder? 

What would you guys have done? Maybe just remove the grid cap clamp and put shrink tube over the wire and then solder that clamp back on (ugly)? The rest of my grid cap wires were replaced.

[morzh]

It is weird it did not melt off. Yes I've heard (and seen) wire welding, but that was in Soviet radios, and I've never seen welding in the civilian radios in the US, let alone to the coil solder tab.
I still think it is solder, but it could be oxidized, and I often see that oxidized solder is not easily melted by even a very hot soldering gun.
If I need to melt that kind of solder, I apply molten solder with flux (rosin core solder wire) right to the spot with hot enough solder tip.

This said, I rarely (if ever) try to desolder wires at the solder tabs on coils: the coils are easily damaged.

In your situation, what I would do:

- take a scalpel, scrape the solder tab (solder or the metal where there is no solder, but which would be accessible to the solder tip) and see what color it is. You should be able to see if it is copper/phosphor bronze or something that is yellow/reddish, or it stays greyish white, which would indicate solder.
If it is metal contact, scrape it well down to bare metal, and solder to it with usual tin-led solder. If it is solder, scrape well until shiny, and try to solder with tin-let-rosin core, at somewhat higher (not too high) temperature, making a bead; then solder wire to it.

I do not claim to have seen everything; there are folks here who have seen tons more than I have; so maybe they will have more ideas about what your contact is, though this being a 60 (have just finished one and worked on another one before, with coild rewinding), I doubt it is anything other than regular contact with regular solder.

[dconant]

Yep Mike I was puzzled. I did work with a dab of solder on the tip with flux. No go so I scrapped what little wire I had to work with and that did the job. I didn't want to mess around too much and wind up with a broken coil wire. Anyway it is back in the radio and playing nicely. Thanks for the info. Did have to mess with one of the wires to get the radio to stop squealing. Little bit touchy in that area. On your 60 I just can't imagine how you managed to get all those wires back without having squealing issues.

[morzh]

Dunno. I tried to have all wires more or less where they originally belonged, and have shields installed with the one grid wire inside the shield.

[Chas]

Weller 325 watt gun.

Try an iron not much more than 100 watts with a large copper tip so heat is stored in the tip. If still reluctant, try using SMD low temperature rework solder. The low temp alloys will amalgamate with the higher temp alloy and lower the temperature of the original and melt the joint.

Chas