Try scraping it clean with a sharp blade. Sometimes terminals get some sort of surface contamination that is really, really difficult to remove; I've just had to throw out some otherwise nice tube sockets because of that. With a wire, you might have a chance if the base metal is copper.
If all else fails, you could do a bit of surgery and replace that recalcitrant lead.
If all else fails, you could do a bit of surgery and replace that recalcitrant lead.
HipoFutura said:
If scraping doesn't work, try using flux with chloride in it (plumbers flux). Often recalcitant oxides can react with organic fluxes forming a tough burned on glop that's hard to remove. I've used scotchbrite and/or sandpaper to expose "virgin" metal on these older leads. If it stays silvery (not copper) you've got some other wire type that needs an aggresive flux.
hope this helps...
auplater
Good to hear you worked it out. 
Some thoughts. Naturally, you want to be careful with copper as it is easy to break. If you lay the stranded wire on a hard surface and scrape it with an angled blade like spreading butter on toast, you'll expose enough bare copper to begin the bonding process. Now the iron will be able to heat the copper and the contamination may break down more readily.
Some thoughts. Naturally, you want to be careful with copper as it is easy to break. If you lay the stranded wire on a hard surface and scrape it with an angled blade like spreading butter on toast, you'll expose enough bare copper to begin the bonding process. Now the iron will be able to heat the copper and the contamination may break down more readily.
SY said:
Sy, All,
I bought a pile of NOS bakelite octal sockets that refuse to wet with solder. By painting the terminals with dilute muriatic acid and a paint brush the oxide layer disappeared quickly and completely. The acid needs to be washed out with a session under the tap however as it will make a conductive film, variably worse with humidity out of the bakelite between terminals if not washed away.
I think I would try some more conservative approaches before resorting to pool acid. Ketchup, Coca Cola, and vinegar are all good ways of cleaning things up. I would have to assume these socket contacts are plated and not well suited to a sledgehammer technique.
Better still, there is a material known as De-Ox-It that the pro techs here give very high marks.
I use pool acid for stripping plating away... not restoring it. Diluting it makes total sense... who has a good ratio... of pool acid to water?
Better still, there is a material known as De-Ox-It that the pro techs here give very high marks.
I use pool acid for stripping plating away... not restoring it. Diluting it makes total sense... who has a good ratio... of pool acid to water?
poobah said:Diluting it makes total sense... who has a good ratio... of pool acid to water?
Using a small paintbrush to apply just a film of the acid prevents stripping of the plating that would occur eventually if the terminals were literally dipped in an acid bath. Muriatic acid I buy from the hardware store comes in a 4 litre plastic jug and smokes when the screw cap is removed. IIRC the concentration is in the 30 percentile range. I take that and use about 1 fluid oz added to the 8 cups of water going into a coffee maker hopper to clean a coffee maker (beats the sh*t out of useless CLR sold for this purpose BTW). For deoxing sockets and other tube amp vintage parts I'll mix what comes out of the bottle with one or two equal parts of water.
There was an article about acid cleaning tube sockets in one of the old Audio Amateur or Glass Audio mags. I tried it, with some success. I used the pool acid straight (since I already had a gallon for adjusting my pool's pH), but only for a very short time. I figured that dilution and time were tradable. I poured a bit into a bottle cap to a height that would cover the lower 60% or so the tube pins (outdoors!). You don’t want to get acid on the glass-metal frit seal. Then I carefully set the tube into the cap resting the pins on the bottom. After only few seconds in the bath, I rinsed the tube with tap water, and then submerged it into a second bottle cap with a solution of baking soda (sodium bicarbonate) to neutralize any remaining acid. I set the fluid level higher in this buffering bath, to cover the entire length of the pins and even the flat glass bottom too. This way, any tiny bit of acid vapor or spray that might have hit the frit would be neutralized too. Finally I washed the tubes very thoroughly with running tap water, and finished with a spritz of distilled water from a squeeze bottle to remove any dissolved mineral residue from the tap water. A hair dryer made sure the tubes were dry in no time. The acid etching not only cleans the oxides off, but it creates a matte texture on the pins that might make for a good pressure contact with the socket.
From a document I had saved on Dumet Seals:
"In 1915, Colin G. Fink filed a patent for a revolutionary new type of seal. Nickel/Iron alloys can be made with a wide range of expansion co-efficients which cover that of glass. The problem is that seals made with Nickel/Iron wire are often porous. It also suffers a chemical reaction with the glass during the sealing operation which causes gas bubbles to form. Copper seals well to glass, but has the wrong expansion co-efficient. The step which Mr. Fink made was to make a wire which has a Nickel/Iron core bonded to a sleeve of copper. The thicknesses and expansion co-efficients are chosen so that the radial expansion matches that of the glass. The axial expansion is less than the glass, but the stress is taken up by the copper sheath. This type of seal is now known as a Dumet seal. It is pronounced 'dew-met'. It is used in CRTs, vacuum tubes, fluorescent tubes and filament lamps. Dumet seals can be easily identified by their red appearance within the glass."
"In 1915, Colin G. Fink filed a patent for a revolutionary new type of seal. Nickel/Iron alloys can be made with a wide range of expansion co-efficients which cover that of glass. The problem is that seals made with Nickel/Iron wire are often porous. It also suffers a chemical reaction with the glass during the sealing operation which causes gas bubbles to form. Copper seals well to glass, but has the wrong expansion co-efficient. The step which Mr. Fink made was to make a wire which has a Nickel/Iron core bonded to a sleeve of copper. The thicknesses and expansion co-efficients are chosen so that the radial expansion matches that of the glass. The axial expansion is less than the glass, but the stress is taken up by the copper sheath. This type of seal is now known as a Dumet seal. It is pronounced 'dew-met'. It is used in CRTs, vacuum tubes, fluorescent tubes and filament lamps. Dumet seals can be easily identified by their red appearance within the glass."
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