Blackened pins on NOS valves, any tips?

[emeritus]

Has anyone tried Vaseline? The method of joining high voltage aluminium bus bars used to be to prepare the mating surfaces by thickly applying Vaseline, filing the surfaces bright through the Vaseline, and then bolting up without removing the dirty Vaseline. Unlike automotive greases which are designed to stay put, Vaseline will flow readily under pressure to provide a low resistance contact path. Dad always used to use Vaseline on the 4mm wander plugs he used on some of his radios, and used to use it on the mating surfaces of the terminals of car batteries when fitting them.

[Bazz4CQJ]

Originally Posted by John M0GLN

I've got an English Electric C178A/5894 ( Mullard equivalent QQV06-40A) with all it's pins blackened, I always assumed it was perhaps some silver oxide, a quick look on the web and unless it's the way they've been photographed quite a few of them also appear black, the one attached is from 'The National Valve Museum', website.

That does look black, but did it get like that working within it's intended limits or had it been abused?

Re Vaseline, that's going to decompose at a relatively low temperature. I'd guess that if a valve runs so hot that it blackens its pins, it will certainly destroy the Vaseline.

B

[Maarten]

Originally Posted by Diabolical Artificer

I cleaned up some valve base pins yesterday with a fibre pen then tinned them with solder, could you do likewise?

Andy.

Tinning contacts that go into a connector is at best dubious. Tin is too soft for that and will in time crackle and oxidise, causing bad contacts.

[John M0GLN]

Originally Posted by Bazz4CQJ

That does look black, but did it get like that working within it's intended limits or had it been abused?
B

I was given the valve about 25 years ago and it's just been sitting in it's box since then, sorry but I don't know any more of it's history other than it was like that when I got it..

John

[Diabolical Artificer]

"I've got an English Electric C178A/5894 ( Mullard equivalent QQV06-40A) with all it's pins blackened," I a few of these upstairs, Mullard QQV06-40A's, they have a gold coloured plating on the pins.

"Not sure I would go that far Andy?
Tinning them will make them even harder to insert into a 'tight' socket. And not sure there is any benefit?" I wouldn't do it myself, was responding to concern's that cleaning up the pins with a fibre pen would result in more corrosion. Tinning is really thin if you use old solder braid, don't think it would add much to the diameter, a thou at most.

Andy.

[John M0GLN]

Further to my post #24, having dug the valve out of storage I thought I might as well try an experiment, enough depth of warm water in a tumbler to submerge the pins with a spoonful of citric acid crystals and after 20 minutes virtually all the black had gone, any remaining just wiped off with a tissue. The citric acid will be the same as the lemon juice Goldieoldie suggests in post #17 but might be stronger. The pins now look new.

John

[joebog1]

Stoopid as I am, have you tried plugging the valve in and running it?
or are we all discussing somthing that "perhaps may happen" in the future?
As Catweazel said " Mayhap, Mayhap"
Joe

[ex 2 Base]

Could that Black be Silver Oxide. When I worked for BR (remember them when the trains ran on time and few cancellations) we were instructed to leave the oxide alone. Ted

[CambridgeWorks]

I remember a tv workshop I worked in 50 years ago had a ball of plasticine that was mixed up well with carborundum. Keep pushing the valve in until clean. Only practical for sealed glass base pin types though, such as B7G, B8A, B9A
Rob

[RF Burn]

Has anyone tried ordinary detergent (washing powder)? To clean valve pins, especially the ones on QQV03-20, QQV06/40 and QQV07/50 tetrodes, soak them for a couple of minutes in a fairly strong solution of washing powder in hot water, then brush (now) the loose gunk off the pins with a toothbrush or similar, a quick swill under the cold tap usually leaves the pins all nice and shiny. This works for 'gold' or 'silver' plated as well as the standard B9A/B8A/B7G pins.

Be careful, however, as this detergent solution will quickly remove most markings on the glass envelope or enter through any holes in octal bases and leave a mess inside.

[Andrew B]

The only time I have ever had problems with valve contacts were on those awful "side contact" valves, they were a terrible idea.