Old solder and cloth insulation

I am restoring a pair of Mark III amps and am (mostly) enjoying the process. The chassis have been cleaned and polished with "okay" results, the new cap boards have worked out very well (thanks Sal) and the amps sound pretty good (when they aren't apart on the bench ... like now). I have added the forward diodes to the 5AR4 and I just finished pulling and repainting one set of transformers. Those cloth insulated wires have been soldered in place for 45-50 years and the original builder really did a good job of wrapping the wires onto the tube sockets before soldering... making my job less fun. Can any of you experts share some tips on desoldering these sorts of connections without burning the cloth, breaking the stripped portion of the wire off and getting them back in place so the underside of the amp looks reasonably undisturbed? Obviously building new from scratch is whole other kettle of capacitors versus reworking a half century old piece. I am looking for ideas on tools and techniques that have worked well for you.
...j

de-soldering is not much fun...

Do you have slack in the wire so you can sacrifice the ends?

dun know.. Not much I can add

Hi,
Ok as the tube newbe I take a stab at this, First I would think removing the wires from ther soldered terminals would be better than cutting and resoldering back in place. This said I would start by taking rosin and coating the old connections with a flux brush( plumbing flux would work not acid flux )this should help dissipate heat in the joint and if needed add some new fluxcore solder to it. You might find that doing this will make the solder connection look and be like new and be done with it. When I recently built my amp with vintage transformers I found the old wires after being stripped had surface corrosion and would not solder easy. I had to spread the strands out some and use " Scotch Brite " to clean them some and also added a small amount of rosin flux to the joint while soldering and that helped alot. Oh forgot that I tinned them before wraping the terminals, Makes for a neater job I think. If you are set on removing the wires the same advice above should help, you need to get the heat transferred to the joint evenly and there will be less chance of burning and over heating components, if all the solder is heated evenly and not oxidising you should be able to pull and twist the wires free. I hope this helps and your house does not burn down with this advice

Thanks, Dave

Of course cutting vintage transformer wires is not an option. I ended up using a set of stainless steel dentists tools (Harbor Freight) to help speed up the de-tangling process and avoid excessive heating. Some of the ~50 year old cloth insulation shows a bit of scorching as the cloth is old and dry, and some of the wires were just plain hard to extricate. Re-assembly was a pleasure. If someone reworks this amp again 50 years from now I hope they will find my re-wiring job easier to deal with! They may complain about having to sand through four layers of primer and enamel though I was surprised by how thin the factory gray paint was. No primer. It's no wonder why these things rust.

A "solder sucker" really works a treat! The kind that is spring-pump loaded. You can get cheap ones for $5; I've heard the Edsyn brand are good better ones.
Get that solder joint good and melted hot, put the tip right down on it, press the button and most of the solder is gone! If you're lucky, the wire will be loose; sometimes you have to reheat and try again, or use desoldering wick.

Blitzen wrote:A "solder sucker" really works a treat! The kind that is spring-pump loaded. You can get cheap ones for $5; I've heard the Edsyn brand are good better ones.
Get that solder joint good and melted hot, put the tip right down on it, press the button and most of the solder is gone! If you're lucky, the wire will be loose; sometimes you have to reheat and try again, or use desoldering wick.

I tried the suction pump but it requires more heating than I was comfortable with applying. The dentist's pick worked the best of all the things I tried. During reassembly I made the mistake of using flux removing spray on a few of the new joints. All it did was blow sticky rosin onto the previously clean underside of the chassis. This has been an enjoyable and educational journey in any case. Later tonight I will assemble the second Mark III and bask in some 6550 glow.

--when removing old solder, i often put solder on the joint as though i was resoldering it--it helps it flow-then use the solder sucker-also at times if the wire is loose while the joint is still fluid work the wire until it cools -sometimes this will "kill" the joint then you can work from there-i have saved the wire-only to have it break when reassembling-not having any extra length-sadly i had to splice-the dental pics are a big help

howardnair wrote:--when removing old solder, i often put solder on the joint as though i was resoldering it--it helps it flow-then use the solder sucker-also at times if the wire is loose while the joint is still fluid work the wire until it cools -sometimes this will "kill" the joint then you can work from there-i have saved the wire-only to have it break when reassembling-not having any extra length-sadly i had to splice-the dental pics are a big help

Yes, precisely my concern. I had the stripped portion of one wire break off during disassembly when I was too vigorous in trying to free it from the tube socket pin. Absolutely my error ...though I still mumbled curses at some unknown person who did the original assembly of this Mark III half a century ago--and who wrapped each wire SECURELY before soldering. Of course they were following Dyna's instructions in so doing. In this day and age of surface mounting and direst die-on-board manufacturing the Dynaco instructions seem like gross overkill. Especially to those of us who are trying to undo those joints 50 years later without scorching the cloth insulation or breaking precious bits of copper off the ends!
...j