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Help cleaning tube pins

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I have some 9 pin noval Western Electric tubes with badly oxidized pins. At first I thought the heaters were burned out because of the oxidation! I tried soaking the pins in vinegar overnight but that had no effect. Tarn-X, Bleach, and a paste made from non abrasive cleanser all had no effect. Even scraping the pins with a knife blade doesn't accomplish much. The specs say the pins are "Sylvania alloy number 4", which is made from nickel, iron and chrome. My next thought is chrome polish or a small wire wheel in a dremel tool. :bigeyes:
My next thought is chrome polish or a small wire wheel in a dremel tool.

Chrome polish won't do anything if a knife blade doesn't. A wire wheel on a dremel is probably your next course of action. In the past I have used a 6 or 7 inch diameter fine wire wheel (arbor mounted) on a 1725 RPM bench motor. (read below)

Using this method is somewhat risky. You must keep a very firm grip on the tube as the wheel may try to grab it from your hand and hurl it to the floor. Keeping the pins below center and/or tilted downward will help avoid this. VERY IMPORTANT: don't use a faster speed motor then 1725 rpm with this size wheel because the wires tend to come off the wheel as speed increases. Especially with todays cheap garbage Chinese made wire wheels. WEAR EYE PROTECTION!

As a last resort try a mild solution (5:1) of hydrochloric (muriatic) acid for a few seconds or minuets. You will need to neutralize the acid on the pins with a solution of baking soda and thoroghly rinse very well afterwards. If the pins are that oxidized, you don't have much to loose since you can't use them anyway. Needless to say, wear eye protection here too!

I gently clamp the tube (using rubber or bubble-wrap) and use small strips of 1200 grit sandpaper to clean/polish problem pins. This method is mainly because I haven't been able to afford a Dremtel yet. It's somewhat time consuming -- 10 - 20 minutes per tube because moderate care is needed. But it works quite well. 1200 sandpaper is also fine enough a grit not to thin out the width of novar tube pins. (A possible problem with some other over-zealous methods!)

Bill Perkins of PEARL has a PDF called Making Contact with your Tubes that outlines some suggestions, and might be worth checking out.
I saw no mention of phosphoric acid. Naval jelly may do it. Use a Q-tip and leave it on for 10-15 minutes or more.

Vinegar usually does it for anything other than deep corrosion. Do you stand them in vinegar for an hour or so? Use an old plastic bottle top.

If you have a Loctal with the bad corrosion use a wire brush before naval jelly.

A word of warning. Standing a Loctal in vinegar is a disaster. When the tube is biased it will crack. It evidently goes up into the pins and expands with heat.

Hope this helps, Mark
hailteflon said:
I saw no mention of phosphoric acid.
I did try standing a bunch of tubes in some coke (-a-cola ! ) which contains posphoric acid (same thing uses to clean coins) for 48 hours. Seemed to do absolutely nothing (except when I got it on on the tube proper it did a great job of wiping off the tube labels *sigh*)

Naval jelly should work (though I've not tried it).

Some tubeophiles talk about "cleaning pins" when what they actually mean is that they really want "shiney". In which case, using the very fine sandpaper or dremtel polishing method is the only way to get it.
Naval jelly is many times stronger than coke. Coke has just enough acid to start tooth decay.

Phosphoric acid in rust dissolver will leave a gray coating which is a corrosion inhibitor.

Shining the pins to bright metal is a mistake. They will immediately begin to corrode. Putting phosphoric acid on them afterwards will apply corrosion inhibitor.

You can find Rust Cure and other rust dissolvers at the hardware store (and also auto parts) but they are liquid and will melt the labels. They do leave a phosphorus coating to inhibit corrosion.

Naval jelly is a thick creme that won't dry for over an hour. It was originally developed to strip rust from boat hulls.

TarnX is also an acid, but it won't do much for rust. It is specifically for silver type tarnish. Incidentally, the black tarnish is also a type of corrosion. I have opened dead ceramic cartridges and found the ribbon leads had turned to black powder.

I avoid sanding on the pins because it stresses the glass seal and could start an air leak. Then the ominous white getter.
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