Cleaning oxidized tube sockets on Fender Red knob twin tube amplifier

[jalexquijano]

What tool and solution should i use to clean oxidized preamp tube sockets on my Fender red knob twin tube amp? Should i use a small nylon or plastic brush or should i scrape the rusted pins with a knife?

[nevetslab]

I've used the smallest Wiha bladed screwdriver, size 260 1.5 x 40 as well as a Pace P/N 6993-0200, which is normally used to clean the throats of their De-Soldering Iron tips and irons. It has a wide range of cleaning wires, each having a textured metal finish to burnish the insides of the desoldering iron tips and tool throat, but, also work well for burnishing the insides of the tube sockets. I've attached a link to Newark's listing of the item, which also has the data sheet for the cleaning tool, On the larger power tube sockets, pipe cleaners work, dipped in DeOxit.

https://www.newark.com/pace/6993-020...it/dp/70C2397#

[Leo_Gnardo]

I've used the smallest Wiha bladed screwdriver, size 260 1.5 x 40 as well as a Pace P/N 6993-0200, which is normally used to clean the throats of their De-Soldering Iron tips and irons. It has a wide range of cleaning wires, each having a textured metal finish to burnish the insides of the desoldering iron tips and tool throat, but, also work well for burnishing the insides of the tube sockets. I've attached a link to Newark's listing of the item, which also has the data sheet for the cleaning tool, On the larger power tube sockets, pipe cleaners work, dipped in DeOxit.

https://www.newark.com/pace/6993-020...it/dp/70C2397#

KOOL! I'mma have to score that Pace item. FWIW I've used dental mini brushes intended for between-the-teeth cleaning, with a drop of DeOxit, for small sockets. You can find 'em at most large grocery stores or pharmacies in the dental devices display. Pipe cleaners - with bristle not the soft ones - for octal and other larger sockets. And sometimes the socket is hopeless, you have to replace it.

[jalexquijano]

This is the socket that needs cleaning and tightening. As you see its a lot of wires to desolder and if i can clean it with deoxit d5 and GUM dental proxabrush it is more practical. Amazon sell a deoxit tube socket cleaning kit but i dont think you should be using any kind of chemicals on those terminals.

[Jon Snell]

I use a fibre glass pencil to remove the carbon deposits and prolong the life of the contact spring. Fibre glass does not remove any metal, just residue and carbon build up.
If the contacts are scraped, the conductive material is worn away and it will never recover.
Desoldering tip cleaners, are like a file and do more harm than good in the long run.
If in doubt, replace the socket and it won't come back as a free repair at your cost!

[Helmholtz]

This is the socket that needs cleaning and tightening. As you see its a lot of wires to desolder and if i can clean it with deoxit d5 and GUM dental proxabrush it is more practical. Amazon sell a deoxit tube socket cleaning kit but i dont think you should be using any kind of chemicals on those terminals.

Deoxit D5 is safe on sockets and plastics. But you shouldn't flush the whole socket anyway, just apply a drop to a slim (smallest size for Noval) interdental brush (https://www.amazon.com/TEPE-Interden...451085&sr=8-10 ) and clean the contacts only as Leo said.

The more tricky part is the re-tensioning of the socket contacts. I use a strong steel needle (e.g. the type used with pinboards).

Tube pins can be cleaned with a piece of folded 400 to1000 grid emery paper.

[nevetslab]

I use a fibre glass pencil to remove the carbon deposits and prolong the life of the contact spring. Fibre glass does not remove any metal, just residue and carbon build up.
If the contacts are scraped, the conductive material is worn away and it will never recover.
Desoldering tip cleaners, are like a file and do more harm than good in the long run.
If in doubt, replace the socket and it won't come back as a free repair at your cost!

I hadn't thought of small dia fiber glass rod material for contact cleaning. I like that idea. I'll have to see what's available in 'standard' inventoried diameters of that material. 'Typical' 9-pin tube pins range from 0.92 to 0.97 mm dia while the power tubes range from 2.24 to 2.30 mm dia.

[Helmholtz]

I have problems to visualize how I could clean the side walls of socket contacts with a fiber glass brush. At least with the types I'm familiar. Maybe a picture could explain?

[mozz]

That doesn't look bad at all, i would eat off that chassis. Maybe a drop of deoxit or any type tuner cleaner(showing my age), use a unwanted tube and insert remove a few dozen times.

[nevetslab]

I hadn't thought of small dia fiber glass rod material for contact cleaning. I like that idea. I'll have to see what's available in 'standard' inventoried diameters of that material. 'Typical' 9-pin tube pins range from 0.92 to 0.97 mm dia while the power tubes range from 2.24 to 2.30 mm dia.

I looked on McMaster-Carr, but didn't find any fiberglass rod in the two diameters, I did find Carbon Fiber rod material in those sizes, then in checking back, I see Helmholtz offered a good suggestion with the TEPE interdental brushes, and I ordered a set of those to check out.

[Leo_Gnardo]

its a lot of wires to desolder and if i can clean it with deoxit d5 and GUM dental proxabrush it is more practical. Amazon sell a deoxit tube socket cleaning kit but i dont think you should be using any kind of chemicals on those terminals.

Ah, GUM proxabrush, that's the one! As for chemicals, D5 to clean the gunk off the metal, and follow up with a squirt of non-residue solvent spray to remove most of the D5. Back in the day when it was called Cramolin, the point was made only a few molecules are supposedly enough to maintain good contact. Whatever's left over after the solvent wash, that's enough. Too much of the oily Deoxit left behind can start a new round of corrosion, complicated by coagulated oxidized oil.

Yes it's best to get it done by cleaning, but there comes a time if it doesn't resolve well, you'll have to go through the hassle of replacing the socket. All in a day's work... frustration is part of the job all too often.

[The Dude]

......If the contacts are scraped, the conductive material is worn away and it will never recover.
Desoldering tip cleaners, are like a file and do more harm than good in the long run......

Respectfully, the entire socket pin is "tin" and conductive. Sure, a slight amount of conductive material is worn away, but it's not like the pins are made of wood and dipped in a conductor. I fail to see how slightly burnishing the contact could hurt anything as long as the socket pin remains tight to the tube pin. Tube amp techs have been burnishing tube socket pins (probably) since tube sockets were invented. I don't see how it can/could cause any sort of "non-recoverable" situation.

[Jon Snell]

i always use the least destructive method. Some old contacts are tin plated steel and when the tin is gone make a poor contact, some are tin plated brass and do not suffer from wear in the same way. Without being there to work on them, it is guess work.
Sometimes a spray of contact cleaner will work but it depends on the circumstances including the age of the sockets.
Most older McMurdo sockets I successfully replace the connectors and leave the original bakelite bases. Easier and quicker than replacing the sockets but International Octal bases are generally OK after cleaning and re tensioning the contacts.
There are many variables.

[SoulFetish]

A couple of things in response;
I posted about re-tensioning the sockets a while back. I'll try and find the thread as an example of the tool and technique I've had a lot of success with.
If any of the socket terminals are heavily built up with oxide and grime, I don't spend the time to try and restore it.
Rather than replace the whole socket, however, I will transplant the socket pin(s) from a new donor socket. Takes no time at all, and is very easy once you've done it.

... ah, here is the "tube socket harpoon", as coined by Leo Gnardo:
https://music-electronics-forum.com/...361#post733361

[g1]

... ah, here is the "tube socket harpoon", as coined by Leo Gnardo:

Commercially available as a "teasing needle" as noted later in that thread. Some have straight needle, some have angled.