Use of switch cleaner on valve bases.
 

What are other members views on using switch cleaner such as Servisol 10 on valve bases in order to improve pin contact. I have done this routinely in the past but note one recent comment that it can cause strange problems with valves in RF or IF stages.

Re: Use of switch cleaner on valve bases.
 

It was me!

I had a horrible experience with a Hallicrafters SX28 "Super Skyrider" (anyone got one they want to part with?), when I was just starting out with old radios, about 20 years ago. I had a lot of crackling valve base type problems, and so decide to apply switch cleaner to all the valve bases. The result was nice clean bases and pins, and no crackles, but also no signals!

What I later surmised had happened (several years and a lot of experience on), was that the set suffered from poor performance and had been realigned without cleaning the pins and bases, which had extra stray capacitance due to the oxide layer on the contacts. When I cleaned the bases and pins, the alignment went out, and the signals disappeared. This was born out by the fact that re-alingment cured the problem, the theory came later!

Hence my warning to be careful about switch cleaner on RF and IF stages. To be fair, in a domestic set that has probably never seen a signal generator since it was made, it should improve matters, but now that so many "restored" sets are coming on the market, I'll stick by my advice, especially if you don't have a signal generator that you can use to check the alignment.

Jim.

Re: Use of switch cleaner on valve bases.
 

I use Servisol to clean valve pins, but I spray the pins rather than the base, then quickly place the valve back in the base. I leave it a couple of minutes or so to allow any surplus cleaner to evaporate before switching on. I've never had any problems doing this. I've found this method of cleaning particularly effective with loctal valves.

I did wonder whether is it possible that the chemicals in Servisol could damage valve bases, particularly those of bakelite or ceramic manufacture?

Re: Use of switch cleaner on valve bases.
 

I have now started to put a drop of contact lubricant on each pin before replacing in socket. Electrolube pen type containing contact oil 2X.
Paul

Re: Use of switch cleaner on valve bases.
 

I was given a tip on cleaning valve pins many years ago by a TV engineer who doubled as a night-school lecturer on a course I attneded, when valve TV's were still much in evidence. I use it to this day.

Take a block of hardwood, say 50mm cube, and drill a hole in it with a slickbit ("flatbit") say 25mm diam to a depth of about 25mm.

Then take a piece of Plasticine, and nead into it iron filings so that the Plasticine is thoroughly impregnated with the filings. Then fill the hole in the bock with the mixture.

All you have to do to clean the pins is to plunge them in and out of the plasticine a few times, and the pins come up shiny, and as good as new.

It really does work, and the plasticine seems to last for ages.

I just use a piece of scrap cast iron (rather than mild steel), grind it away on an electirc grindstone till I have enough filings, then collect them up with a magnet.

If there is some carborundum mixed in from the grindstone, so much the better.

Hope that helps!
David Taylor.

Re: Use of switch cleaner on valve bases.
 

Cleaning the pins of the valve with fine wire wool works well. If you then replace the valve into it's base a few times , this cleans the sockets in the valve base.
But take care that small strands of wire wool are left between the pins !!

Simon.

Re: Use of switch cleaner on valve bases.
 

Hi
I have found that a model railway Track cleaning rubber
does an excelent job on v/v pins and other sliding contacts.
martyn.

Re: Use of switch cleaner on valve bases.
 

Hi

I use Naval Jelly. It's sold for removing rust and contains Phoshphoric Acid. Brush it on. Let stand for 1 minute and wash off with water.

Although sanding, steel wool and other abrasives will work they scratch the plating. The above method makes the pins like new.

Norm

Re: Use of switch cleaner on valve bases.
 

I find the most effective product for cleaning switch contacts and valve pins/sockets is Kontakt 60. This is better at removing dirt & tarnish than Servisol Super 10. I spray some onto a cotton bud and apply this to the contact rather than soak the whole thing. It is available from Rapid Electronics (www.rapidelectronics.co.uk) in a 200ml aerosol.